datalogs LEAN AFR
Re: datalogs LEAN AFR
No, Sorry I don't. I use Zeitronix to log the fuel pressure. I have a friend who was still lean even after replacing the stock pump with the SL55 pump. I Think that the restriction is from the injectors.
Senior Member
Re: datalogs LEAN AFR
I was running lean for quite a while. Re tunes weren't helping, not sure exactly why. However, after having my meth problem, removing and reinstalling everything, sending the injectors off for service, my AFR's are beautiful. (11.8 to 12.2) Being a non believer or hard headed, I stacked my Code3 with 178 crank pulley. I never made a full pull to redline because AFR's hit 16 accelerating in second gear. On went the Pierburg SL55 fuel pump and now the only place of concern is at the top of 3rd. where I hit 14 AFR. So, the pump helps. (1/4 times were identical stacked so the Code3 is back in the closet)
Summing up, start by optimizing what you have. Remote tunes are difficult for any tuner so try to make it to your nearest E/C location or preferred tuner for a dyno tune. If that can't fix it, next is the pump. Servicing the injectors is a good idea IMO. I did mine because my car sat from 9/05 until 6/08. BTW, I have some fresh serviced injectors I'll let go cheap!
Les
Summing up, start by optimizing what you have. Remote tunes are difficult for any tuner so try to make it to your nearest E/C location or preferred tuner for a dyno tune. If that can't fix it, next is the pump. Servicing the injectors is a good idea IMO. I did mine because my car sat from 9/05 until 6/08. BTW, I have some fresh serviced injectors I'll let go cheap!
Les
Join Date: Apr 2009
Location: Baton Rouge, LA
Age: 51
Posts: 414
Likes: 0
Received 0 Likes
on
0 Posts
Re: datalogs LEAN AFR
Gotcha. I worked with Jerry on multiple tunes to get where I am at. I will run it again next week and see if the ECU has adjusted any. I think Rob sells a fuel gauge that I may buy.
I am with you on the injectors. I was going to go to the fuel filter, regulator, and then injectors if necessary.
I am with you on the injectors. I was going to go to the fuel filter, regulator, and then injectors if necessary.
Join Date: Jan 2012
Location: SouthTX
Posts: 1,098
Likes: 0
Received 0 Likes
on
0 Posts
Re: datalogs LEAN AFR
here is another link that I like
Stealth 316 - Injector Duty Cycle Calculation
I realized I'm an idiot, I posted without quoting who I was posting to....
I didn't pay attention to the the fact that Austin hijacked the thread lol.
Jesse: you have way to much fuel or a timing issue it appears...hard to say without looking at your tune. It looks like you need to pull some fuel as has been stated already but without seeing what your car is running for timing it's hard to say exactually.
I didn't pay attention to the the fact that Austin hijacked the thread lol.Jesse: you have way to much fuel or a timing issue it appears...hard to say without looking at your tune. It looks like you need to pull some fuel as has been stated already but without seeing what your car is running for timing it's hard to say exactually.
I was running lean for quite a while. Re tunes weren't helping, not sure exactly why. However, after having my meth problem, removing and reinstalling everything, sending the injectors off for service, my AFR's are beautiful. (11.8 to 12.2) Being a non believer or hard headed, I stacked my Code3 with 178 crank pulley. I never made a full pull to redline because AFR's hit 16 accelerating in second gear. On went the Pierburg SL55 fuel pump and now the only place of concern is at the top of 3rd. where I hit 14 AFR. So, the pump helps. (1/4 times were identical stacked so the Code3 is back in the closet)
Summing up, start by optimizing what you have. Remote tunes are difficult for any tuner so try to make it to your nearest E/C location or preferred tuner for a dyno tune. If that can't fix it, next is the pump. Servicing the injectors is a good idea IMO. I did mine because my car sat from 9/05 until 6/08. BTW, I have some fresh serviced injectors I'll let go cheap!
Les
Summing up, start by optimizing what you have. Remote tunes are difficult for any tuner so try to make it to your nearest E/C location or preferred tuner for a dyno tune. If that can't fix it, next is the pump. Servicing the injectors is a good idea IMO. I did mine because my car sat from 9/05 until 6/08. BTW, I have some fresh serviced injectors I'll let go cheap!
Les
What is the cost on a looped fuel rail from TTM? This is the only real way to equalize fuel pressure and the best way to get a fuel pressure guage sensor to read accuratley right?
Join Date: Jan 2012
Location: SouthTX
Posts: 1,098
Likes: 0
Received 0 Likes
on
0 Posts
Re: datalogs LEAN AFR
Here are some more datalogs (finally figured out how to add markers). This is cruising speeds and the occasional blip throttle. The AFR is really strange. It will be at 14.7 during closed loop, then jump up to max at 21 AFR, then comes down all without the throttle really being manipulated. Any time the throttle is touched the AFR's richen.
datalogsafrinconsistent_zpsc9429112.jpg
datalogsafrinconsistent2_zps56a47e9d.jpg
datalogsafrinconsistent1_zpsc0fd0590.jpg
datalogsafrinconsistent_zpsc9429112.jpg
datalogsafrinconsistent2_zps56a47e9d.jpg
datalogsafrinconsistent1_zpsc0fd0590.jpg
Re: datalogs LEAN AFR
Let me see if I can simplify this and try to explain the problem with the lean issue a lot of people seem to have. This car in the stock form has near perfect ARF's, this is because for the amount of boost (forced air) the engine is getting, the injectors and the pump are sufficient in both flow and volume. The stock fuel filter regulates the pressure to the rail, we need around 54 to 60 psi at the rail. The stock pump is also capable of handling the pressure and the flow at stock settings.
Once we starting adding things like pulleys to increase boost this is where we run into trouble. As we add more forced air into the system we then need to add more fuel to the system in order to equalize the equation. You can't add one without the other. What most people do is add a pulley then get a tune to try to add more fuel. This combination will usually work if you are only adding only 1 or 2 more lbs of boost. In this scenario the stock fuel system is sufficient, but if you want more than 2 lbs of boost you start to ask a fuel system to do things it doesn't have the ability to do.
Lets start by looking at the fuel pump, the fuel pump on these cars are quite simple, they are either on of off, they are not regulated by voltage therefore the flow is constant. The problem with the stock pump is it can not keep up with the volume of fuel we are asking it to. When this happens we experience a drop in pressure at the rail at WOT. The numbers we were seeing were 54 psi at the rail during idle and 42 psi at the rail at WOT. At that point it became pretty apparent we needed a new pump. When you replace the pump it has to be replaced with a HIGH flow pump, it is important that it is able flow enough volume to keep up with the demands. Keep in mind the stock fuel filter is still being used, it has sufficient fuel flow characteristics to feed the system.
Next issue to address is the injectors. Remember as we add more air, we need to add more fuel. Since we just added a new high flow pump we now know we have sufficient fuel flow and pressure to the rail. Now how do we get the fuel into the engine, obviously it's via the injectors, so naturally we tell the computer to increase fuel flow through the injectors. The computer in return says "ok" and presto changeo problem solved, right? The answer is maybe...if you are running low to mild boost pressure you may be ok, but if you are running over 16 lbs ish you are probably running out of injector as well. This is why no matter what tune you throw at it it doesn't solve the problem. Although the computer is telling the injectors to add more fuel, they physically are not capable of keeping up with the demands that we are asking them to do. Even if they are able to "just" keep up, the duty cycle at which we are asking them to operate at significantly decreases their life span. So the solution as you may have guessed is bigger injectors, ones that can not only handle the volume but can also do it at a significantly lower duty cycle. This allows you some wiggle room with your tune to add more fuel if needed in the future. It also allows the injector to operate at a much more efficient rate and increases the life span of the injectors.
Moral of the story is, bigger pump, and bigger injectors are needed. Now you may be saying "in theory you may be right, but I think our cars have plenty of injectors and plenty of pump, the pressure is the problem. I think I'll just turn up the pressure to solve the problem". I will tell you with 100% certainty that that is not a solution to the problem, that is a band aid fix for a wound that needs a tourniquet. A lot of information that we have learned about this car has come not only from our race program but also from the SRT division of dodge/chrysler. I have talked extensively with a lot of the people who were involved with the development of this car. SRT is at our track quite frequently testing the Viper and I have the advantage of picking their brains while they are there.
Any question? Class dismissed!
Once we starting adding things like pulleys to increase boost this is where we run into trouble. As we add more forced air into the system we then need to add more fuel to the system in order to equalize the equation. You can't add one without the other. What most people do is add a pulley then get a tune to try to add more fuel. This combination will usually work if you are only adding only 1 or 2 more lbs of boost. In this scenario the stock fuel system is sufficient, but if you want more than 2 lbs of boost you start to ask a fuel system to do things it doesn't have the ability to do.
Lets start by looking at the fuel pump, the fuel pump on these cars are quite simple, they are either on of off, they are not regulated by voltage therefore the flow is constant. The problem with the stock pump is it can not keep up with the volume of fuel we are asking it to. When this happens we experience a drop in pressure at the rail at WOT. The numbers we were seeing were 54 psi at the rail during idle and 42 psi at the rail at WOT. At that point it became pretty apparent we needed a new pump. When you replace the pump it has to be replaced with a HIGH flow pump, it is important that it is able flow enough volume to keep up with the demands. Keep in mind the stock fuel filter is still being used, it has sufficient fuel flow characteristics to feed the system.
Next issue to address is the injectors. Remember as we add more air, we need to add more fuel. Since we just added a new high flow pump we now know we have sufficient fuel flow and pressure to the rail. Now how do we get the fuel into the engine, obviously it's via the injectors, so naturally we tell the computer to increase fuel flow through the injectors. The computer in return says "ok" and presto changeo problem solved, right? The answer is maybe...if you are running low to mild boost pressure you may be ok, but if you are running over 16 lbs ish you are probably running out of injector as well. This is why no matter what tune you throw at it it doesn't solve the problem. Although the computer is telling the injectors to add more fuel, they physically are not capable of keeping up with the demands that we are asking them to do. Even if they are able to "just" keep up, the duty cycle at which we are asking them to operate at significantly decreases their life span. So the solution as you may have guessed is bigger injectors, ones that can not only handle the volume but can also do it at a significantly lower duty cycle. This allows you some wiggle room with your tune to add more fuel if needed in the future. It also allows the injector to operate at a much more efficient rate and increases the life span of the injectors.
Moral of the story is, bigger pump, and bigger injectors are needed. Now you may be saying "in theory you may be right, but I think our cars have plenty of injectors and plenty of pump, the pressure is the problem. I think I'll just turn up the pressure to solve the problem". I will tell you with 100% certainty that that is not a solution to the problem, that is a band aid fix for a wound that needs a tourniquet. A lot of information that we have learned about this car has come not only from our race program but also from the SRT division of dodge/chrysler. I have talked extensively with a lot of the people who were involved with the development of this car. SRT is at our track quite frequently testing the Viper and I have the advantage of picking their brains while they are there.
Any question? Class dismissed!
Re: datalogs LEAN AFR
try datalogging this way. forget about closed loop for now.
log afr, timing, rpm, engine load. from 2000 rpm in 3rd gear stand on the throttle and take it to redline , watching afr. if your not spiking this will allow the obdII to capture the data as fast as possible . remember rpm may not line up with timing etc due to sample rates. this is how you correctly log. the slow rpm start allows you to watch afr and back out if it goes big lean
if you want to log other parameters let it cool down and keep the samples to 4 or less parameters
log afr, timing, rpm, engine load. from 2000 rpm in 3rd gear stand on the throttle and take it to redline , watching afr. if your not spiking this will allow the obdII to capture the data as fast as possible . remember rpm may not line up with timing etc due to sample rates. this is how you correctly log. the slow rpm start allows you to watch afr and back out if it goes big lean
if you want to log other parameters let it cool down and keep the samples to 4 or less parameters
Re: datalogs LEAN AFR
Let me see if I can simplify this and try to explain the problem with the lean issue a lot of people seem to have. This car in the stock form has near perfect ARF's, this is because for the amount of boost (forced air) the engine is getting, the injectors and the pump are sufficient in both flow and volume. The stock fuel filter regulates the pressure to the rail, we need around 54 to 60 psi at the rail. The stock pump is also capable of handling the pressure and the flow at stock settings.
Once we starting adding things like pulleys to increase boost this is where we run into trouble. As we add more forced air into the system we then need to add more fuel to the system in order to equalize the equation. You can't add one without the other. What most people do is add a pulley then get a tune to try to add more fuel. This combination will usually work if you are only adding only 1 or 2 more lbs of boost. In this scenario the stock fuel system is sufficient, but if you want more than 2 lbs of boost you start to ask a fuel system to do things it doesn't have the ability to do.
Lets start by looking at the fuel pump, the fuel pump on these cars are quite simple, they are either on of off, they are not regulated by voltage therefore the flow is constant. The problem with the stock pump is it can not keep up with the volume of fuel we are asking it to. When this happens we experience a drop in pressure at the rail at WOT. The numbers we were seeing were 54 psi at the rail during idle and 42 psi at the rail at WOT. At that point it became pretty apparent we needed a new pump. When you replace the pump it has to be replaced with a HIGH flow pump, it is important that it is able flow enough volume to keep up with the demands. Keep in mind the stock fuel filter is still being used, it has sufficient fuel flow characteristics to feed the system.
Next issue to address is the injectors. Remember as we add more air, we need to add more fuel. Since we just added a new high flow pump we now know we have sufficient fuel flow and pressure to the rail. Now how do we get the fuel into the engine, obviously it's via the injectors, so naturally we tell the computer to increase fuel flow through the injectors. The computer in return says "ok" and presto changeo problem solved, right? The answer is maybe...if you are running low to mild boost pressure you may be ok, but if you are running over 16 lbs ish you are probably running out of injector as well. This is why no matter what tune you throw at it it doesn't solve the problem. Although the computer is telling the injectors to add more fuel, they physically are not capable of keeping up with the demands that we are asking them to do. Even if they are able to "just" keep up, the duty cycle at which we are asking them to operate at significantly decreases their life span. So the solution as you may have guessed is bigger injectors, ones that can not only handle the volume but can also do it at a significantly lower duty cycle. This allows you some wiggle room with your tune to add more fuel if needed in the future. It also allows the injector to operate at a much more efficient rate and increases the life span of the injectors.
Moral of the story is, bigger pump, and bigger injectors are needed. Now you may be saying "in theory you may be right, but I think our cars have plenty of injectors and plenty of pump, the pressure is the problem. I think I'll just turn up the pressure to solve the problem". I will tell you with 100% certainty that that is not a solution to the problem, that is a band aid fix for a wound that needs a tourniquet. A lot of information that we have learned about this car has come not only from our race program but also from the SRT division of dodge/chrysler. I have talked extensively with a lot of the people who were involved with the development of this car. SRT is at our track quite frequently testing the Viper and I have the advantage of picking their brains while they are there.
Any question? Class dismissed!
Once we starting adding things like pulleys to increase boost this is where we run into trouble. As we add more forced air into the system we then need to add more fuel to the system in order to equalize the equation. You can't add one without the other. What most people do is add a pulley then get a tune to try to add more fuel. This combination will usually work if you are only adding only 1 or 2 more lbs of boost. In this scenario the stock fuel system is sufficient, but if you want more than 2 lbs of boost you start to ask a fuel system to do things it doesn't have the ability to do.
Lets start by looking at the fuel pump, the fuel pump on these cars are quite simple, they are either on of off, they are not regulated by voltage therefore the flow is constant. The problem with the stock pump is it can not keep up with the volume of fuel we are asking it to. When this happens we experience a drop in pressure at the rail at WOT. The numbers we were seeing were 54 psi at the rail during idle and 42 psi at the rail at WOT. At that point it became pretty apparent we needed a new pump. When you replace the pump it has to be replaced with a HIGH flow pump, it is important that it is able flow enough volume to keep up with the demands. Keep in mind the stock fuel filter is still being used, it has sufficient fuel flow characteristics to feed the system.
Next issue to address is the injectors. Remember as we add more air, we need to add more fuel. Since we just added a new high flow pump we now know we have sufficient fuel flow and pressure to the rail. Now how do we get the fuel into the engine, obviously it's via the injectors, so naturally we tell the computer to increase fuel flow through the injectors. The computer in return says "ok" and presto changeo problem solved, right? The answer is maybe...if you are running low to mild boost pressure you may be ok, but if you are running over 16 lbs ish you are probably running out of injector as well. This is why no matter what tune you throw at it it doesn't solve the problem. Although the computer is telling the injectors to add more fuel, they physically are not capable of keeping up with the demands that we are asking them to do. Even if they are able to "just" keep up, the duty cycle at which we are asking them to operate at significantly decreases their life span. So the solution as you may have guessed is bigger injectors, ones that can not only handle the volume but can also do it at a significantly lower duty cycle. This allows you some wiggle room with your tune to add more fuel if needed in the future. It also allows the injector to operate at a much more efficient rate and increases the life span of the injectors.
Moral of the story is, bigger pump, and bigger injectors are needed. Now you may be saying "in theory you may be right, but I think our cars have plenty of injectors and plenty of pump, the pressure is the problem. I think I'll just turn up the pressure to solve the problem". I will tell you with 100% certainty that that is not a solution to the problem, that is a band aid fix for a wound that needs a tourniquet. A lot of information that we have learned about this car has come not only from our race program but also from the SRT division of dodge/chrysler. I have talked extensively with a lot of the people who were involved with the development of this car. SRT is at our track quite frequently testing the Viper and I have the advantage of picking their brains while they are there.
Any question? Class dismissed!
I don't regret the larger injectors, I just regret not having the sense (and time/$$$) to get a proper tune before I raced a week ago. Instead, I went down there on an assumption, and paid the price with slow times despite "adding" horsepower.
It's all about the ability to keep X fuel pressure at Y boost. Yes, we all have similar cars but each car is slightly different in behavior. Pumps, filters and injectors all play a role (as does the altitude, etc).
Good writeup.
SSB SRT6 405hp/401Tq
Re: datalogs LEAN AFR
Excellent summary, and I think it's something that needs to be said over and over.
I don't regret the larger injectors, I just regret not having the sense (and time/$$$) to get a proper tune before I raced a week ago. Instead, I went down there on an assumption, and paid the price with slow times despite "adding" horsepower.
It's all about the ability to keep X fuel pressure at Y boost. Yes, we all have similar cars but each car is slightly different in behavior. Pumps, filters and injectors all play a role (as does the altitude, etc).
Good writeup.
I don't regret the larger injectors, I just regret not having the sense (and time/$$$) to get a proper tune before I raced a week ago. Instead, I went down there on an assumption, and paid the price with slow times despite "adding" horsepower.
It's all about the ability to keep X fuel pressure at Y boost. Yes, we all have similar cars but each car is slightly different in behavior. Pumps, filters and injectors all play a role (as does the altitude, etc).
Good writeup.
Re: datalogs LEAN AFR
Let me see if I can simplify this and try to explain the problem with the lean issue a lot of people seem to have. This car in the stock form has near perfect ARF's, this is because for the amount of boost (forced air) the engine is getting, the injectors and the pump are sufficient in both flow and volume. The stock fuel filter regulates the pressure to the rail, we need around 54 to 60 psi at the rail. The stock pump is also capable of handling the pressure and the flow at stock settings.
Once we starting adding things like pulleys to increase boost this is where we run into trouble. As we add more forced air into the system we then need to add more fuel to the system in order to equalize the equation. You can't add one without the other. What most people do is add a pulley then get a tune to try to add more fuel. This combination will usually work if you are only adding only 1 or 2 more lbs of boost. In this scenario the stock fuel system is sufficient, but if you want more than 2 lbs of boost you start to ask a fuel system to do things it doesn't have the ability to do.
Lets start by looking at the fuel pump, the fuel pump on these cars are quite simple, they are either on of off, they are not regulated by voltage therefore the flow is constant. The problem with the stock pump is it can not keep up with the volume of fuel we are asking it to. When this happens we experience a drop in pressure at the rail at WOT. The numbers we were seeing were 54 psi at the rail during idle and 42 psi at the rail at WOT. At that point it became pretty apparent we needed a new pump. When you replace the pump it has to be replaced with a HIGH flow pump, it is important that it is able flow enough volume to keep up with the demands. Keep in mind the stock fuel filter is still being used, it has sufficient fuel flow characteristics to feed the system.
Next issue to address is the injectors. Remember as we add more air, we need to add more fuel. Since we just added a new high flow pump we now know we have sufficient fuel flow and pressure to the rail. Now how do we get the fuel into the engine, obviously it's via the injectors, so naturally we tell the computer to increase fuel flow through the injectors. The computer in return says "ok" and presto changeo problem solved, right? The answer is maybe...if you are running low to mild boost pressure you may be ok, but if you are running over 16 lbs ish you are probably running out of injector as well. This is why no matter what tune you throw at it it doesn't solve the problem. Although the computer is telling the injectors to add more fuel, they physically are not capable of keeping up with the demands that we are asking them to do. Even if they are able to "just" keep up, the duty cycle at which we are asking them to operate at significantly decreases their life span. So the solution as you may have guessed is bigger injectors, ones that can not only handle the volume but can also do it at a significantly lower duty cycle. This allows you some wiggle room with your tune to add more fuel if needed in the future. It also allows the injector to operate at a much more efficient rate and increases the life span of the injectors.
Moral of the story is, bigger pump, and bigger injectors are needed. Now you may be saying "in theory you may be right, but I think our cars have plenty of injectors and plenty of pump, the pressure is the problem. I think I'll just turn up the pressure to solve the problem". I will tell you with 100% certainty that that is not a solution to the problem, that is a band aid fix for a wound that needs a tourniquet. A lot of information that we have learned about this car has come not only from our race program but also from the SRT division of dodge/chrysler. I have talked extensively with a lot of the people who were involved with the development of this car. SRT is at our track quite frequently testing the Viper and I have the advantage of picking their brains while they are there.
Any question? Class dismissed!
Once we starting adding things like pulleys to increase boost this is where we run into trouble. As we add more forced air into the system we then need to add more fuel to the system in order to equalize the equation. You can't add one without the other. What most people do is add a pulley then get a tune to try to add more fuel. This combination will usually work if you are only adding only 1 or 2 more lbs of boost. In this scenario the stock fuel system is sufficient, but if you want more than 2 lbs of boost you start to ask a fuel system to do things it doesn't have the ability to do.
Lets start by looking at the fuel pump, the fuel pump on these cars are quite simple, they are either on of off, they are not regulated by voltage therefore the flow is constant. The problem with the stock pump is it can not keep up with the volume of fuel we are asking it to. When this happens we experience a drop in pressure at the rail at WOT. The numbers we were seeing were 54 psi at the rail during idle and 42 psi at the rail at WOT. At that point it became pretty apparent we needed a new pump. When you replace the pump it has to be replaced with a HIGH flow pump, it is important that it is able flow enough volume to keep up with the demands. Keep in mind the stock fuel filter is still being used, it has sufficient fuel flow characteristics to feed the system.
Next issue to address is the injectors. Remember as we add more air, we need to add more fuel. Since we just added a new high flow pump we now know we have sufficient fuel flow and pressure to the rail. Now how do we get the fuel into the engine, obviously it's via the injectors, so naturally we tell the computer to increase fuel flow through the injectors. The computer in return says "ok" and presto changeo problem solved, right? The answer is maybe...if you are running low to mild boost pressure you may be ok, but if you are running over 16 lbs ish you are probably running out of injector as well. This is why no matter what tune you throw at it it doesn't solve the problem. Although the computer is telling the injectors to add more fuel, they physically are not capable of keeping up with the demands that we are asking them to do. Even if they are able to "just" keep up, the duty cycle at which we are asking them to operate at significantly decreases their life span. So the solution as you may have guessed is bigger injectors, ones that can not only handle the volume but can also do it at a significantly lower duty cycle. This allows you some wiggle room with your tune to add more fuel if needed in the future. It also allows the injector to operate at a much more efficient rate and increases the life span of the injectors.
Moral of the story is, bigger pump, and bigger injectors are needed. Now you may be saying "in theory you may be right, but I think our cars have plenty of injectors and plenty of pump, the pressure is the problem. I think I'll just turn up the pressure to solve the problem". I will tell you with 100% certainty that that is not a solution to the problem, that is a band aid fix for a wound that needs a tourniquet. A lot of information that we have learned about this car has come not only from our race program but also from the SRT division of dodge/chrysler. I have talked extensively with a lot of the people who were involved with the development of this car. SRT is at our track quite frequently testing the Viper and I have the advantage of picking their brains while they are there.
Any question? Class dismissed!
The car is still not tuned properly because we are having issues with the MAP sensor which seems to give a CEL. Rob has just sent a new one so lets see if this solves the problem. We dont seem to get higher boost then 15psi Even though we are running the 61mm pulley. The map sensor seems to read the atmospherical pressure wrong, the diagnostic is saying "unreasnible atmospherical pressure value"
Will also do a intake pressure test next week.
/Adam
Last edited by Silverarrow; 09-21-2013 at 03:59 AM.
Let me see if I can simplify this and try to explain the problem with the lean issue a lot of people seem to have. This car in the stock form has near perfect ARF's, this is because for the amount of boost (forced air) the engine is getting, the injectors and the pump are sufficient in both flow and volume. The stock fuel filter regulates the pressure to the rail, we need around 54 to 60 psi at the rail. The stock pump is also capable of handling the pressure and the flow at stock settings.
Once we starting adding things like pulleys to increase boost this is where we run into trouble. As we add more forced air into the system we then need to add more fuel to the system in order to equalize the equation. You can't add one without the other. What most people do is add a pulley then get a tune to try to add more fuel. This combination will usually work if you are only adding only 1 or 2 more lbs of boost. In this scenario the stock fuel system is sufficient, but if you want more than 2 lbs of boost you start to ask a fuel system to do things it doesn't have the ability to do.
Lets start by looking at the fuel pump, the fuel pump on these cars are quite simple, they are either on of off, they are not regulated by voltage therefore the flow is constant. The problem with the stock pump is it can not keep up with the volume of fuel we are asking it to. When this happens we experience a drop in pressure at the rail at WOT. The numbers we were seeing were 54 psi at the rail during idle and 42 psi at the rail at WOT. At that point it became pretty apparent we needed a new pump. When you replace the pump it has to be replaced with a HIGH flow pump, it is important that it is able flow enough volume to keep up with the demands. Keep in mind the stock fuel filter is still being used, it has sufficient fuel flow characteristics to feed the system.
Next issue to address is the injectors. Remember as we add more air, we need to add more fuel. Since we just added a new high flow pump we now know we have sufficient fuel flow and pressure to the rail. Now how do we get the fuel into the engine, obviously it's via the injectors, so naturally we tell the computer to increase fuel flow through the injectors. The computer in return says "ok" and presto changeo problem solved, right? The answer is maybe...if you are running low to mild boost pressure you may be ok, but if you are running over 16 lbs ish you are probably running out of injector as well. This is why no matter what tune you throw at it it doesn't solve the problem. Although the computer is telling the injectors to add more fuel, they physically are not capable of keeping up with the demands that we are asking them to do. Even if they are able to "just" keep up, the duty cycle at which we are asking them to operate at significantly decreases their life span. So the solution as you may have guessed is bigger injectors, ones that can not only handle the volume but can also do it at a significantly lower duty cycle. This allows you some wiggle room with your tune to add more fuel if needed in the future. It also allows the injector to operate at a much more efficient rate and increases the life span of the injectors.
Moral of the story is, bigger pump, and bigger injectors are needed. Now you may be saying "in theory you may be right, but I think our cars have plenty of injectors and plenty of pump, the pressure is the problem. I think I'll just turn up the pressure to solve the problem". I will tell you with 100% certainty that that is not a solution to the problem, that is a band aid fix for a wound that needs a tourniquet. A lot of information that we have learned about this car has come not only from our race program but also from the SRT division of dodge/chrysler. I have talked extensively with a lot of the people who were involved with the development of this car. SRT is at our track quite frequently testing the Viper and I have the advantage of picking their brains while they are there.
Any question? Class dismissed!
Once we starting adding things like pulleys to increase boost this is where we run into trouble. As we add more forced air into the system we then need to add more fuel to the system in order to equalize the equation. You can't add one without the other. What most people do is add a pulley then get a tune to try to add more fuel. This combination will usually work if you are only adding only 1 or 2 more lbs of boost. In this scenario the stock fuel system is sufficient, but if you want more than 2 lbs of boost you start to ask a fuel system to do things it doesn't have the ability to do.
Lets start by looking at the fuel pump, the fuel pump on these cars are quite simple, they are either on of off, they are not regulated by voltage therefore the flow is constant. The problem with the stock pump is it can not keep up with the volume of fuel we are asking it to. When this happens we experience a drop in pressure at the rail at WOT. The numbers we were seeing were 54 psi at the rail during idle and 42 psi at the rail at WOT. At that point it became pretty apparent we needed a new pump. When you replace the pump it has to be replaced with a HIGH flow pump, it is important that it is able flow enough volume to keep up with the demands. Keep in mind the stock fuel filter is still being used, it has sufficient fuel flow characteristics to feed the system.
Next issue to address is the injectors. Remember as we add more air, we need to add more fuel. Since we just added a new high flow pump we now know we have sufficient fuel flow and pressure to the rail. Now how do we get the fuel into the engine, obviously it's via the injectors, so naturally we tell the computer to increase fuel flow through the injectors. The computer in return says "ok" and presto changeo problem solved, right? The answer is maybe...if you are running low to mild boost pressure you may be ok, but if you are running over 16 lbs ish you are probably running out of injector as well. This is why no matter what tune you throw at it it doesn't solve the problem. Although the computer is telling the injectors to add more fuel, they physically are not capable of keeping up with the demands that we are asking them to do. Even if they are able to "just" keep up, the duty cycle at which we are asking them to operate at significantly decreases their life span. So the solution as you may have guessed is bigger injectors, ones that can not only handle the volume but can also do it at a significantly lower duty cycle. This allows you some wiggle room with your tune to add more fuel if needed in the future. It also allows the injector to operate at a much more efficient rate and increases the life span of the injectors.
Moral of the story is, bigger pump, and bigger injectors are needed. Now you may be saying "in theory you may be right, but I think our cars have plenty of injectors and plenty of pump, the pressure is the problem. I think I'll just turn up the pressure to solve the problem". I will tell you with 100% certainty that that is not a solution to the problem, that is a band aid fix for a wound that needs a tourniquet. A lot of information that we have learned about this car has come not only from our race program but also from the SRT division of dodge/chrysler. I have talked extensively with a lot of the people who were involved with the development of this car. SRT is at our track quite frequently testing the Viper and I have the advantage of picking their brains while they are there.
Any question? Class dismissed!
Re: datalogs LEAN AFR
This is what we also experienced. That is why I bought the closed fuel rail from Bruce at TTM with the 550cc injectors. Now I can see that the pressure is constantly beteende 56-57PSI and the AFR is still around 10.1-10.3.
The car is still not tuned properly because we are having issues with the MAP sensor which seems to give a CEL. Rob has just sent a new one so lets see if this solves the problem. We dont seem to get higher boost then 15psi Even though we are running the 61mm pulley. The map sensor seems to read the atmospherical pressure wrong, the diagnostic is saying "unreasnible atmospherical pressure value"
Will also do a intake pressure test next week.
/Adam
The car is still not tuned properly because we are having issues with the MAP sensor which seems to give a CEL. Rob has just sent a new one so lets see if this solves the problem. We dont seem to get higher boost then 15psi Even though we are running the 61mm pulley. The map sensor seems to read the atmospherical pressure wrong, the diagnostic is saying "unreasnible atmospherical pressure value"
Will also do a intake pressure test next week.
/Adam
Re: datalogs LEAN AFR
The car is still not tuned properly because we are having issues with the MAP sensor which seems to give a CEL. Rob has just sent a new one so lets see if this solves the problem. We dont seem to get higher boost then 15psi Even though we are running the 61mm pulley. The map sensor seems to read the atmospherical pressure wrong, the diagnostic is saying "unreasnible atmospherical pressure value"
To date, I have not seen a boost figure higher than 17PSI from the 61mm pulley. I was seeing 17.5 with the 65mm pulley, and was much faster because I wasn't dumping the extra fuel from the bigger injectors. And yes, the tune I have is built around the larger TTM injectors... Mine are Bosch EV14, not sure how those differ from the TTM injectors (I know the spray pattern is different.... maybe that's the issue?)
Re: datalogs LEAN AFR
THREE 6S
Join Date: Aug 2007
Location: From North TX..To SoCAL..Now Cnt Philly
Posts: 704
Likes: 0
Received 0 Likes
on
0 Posts
Re: datalogs LEAN AFR
Let me see if I can simplify this and try to explain the problem with the lean issue a lot of people seem to have. This car in the stock form has near perfect ARF's, this is because for the amount of boost (forced air) the engine is getting, the injectors and the pump are sufficient in both flow and volume. The stock fuel filter regulates the pressure to the rail, we need around 54 to 60 psi at the rail. The stock pump is also capable of handling the pressure and the flow at stock settings.
Once we starting adding things like pulleys to increase boost this is where we run into trouble. As we add more forced air into the system we then need to add more fuel to the system in order to equalize the equation. You can't add one without the other. What most people do is add a pulley then get a tune to try to add more fuel. This combination will usually work if you are only adding only 1 or 2 more lbs of boost. In this scenario the stock fuel system is sufficient, but if you want more than 2 lbs of boost you start to ask a fuel system to do things it doesn't have the ability to do.
Lets start by looking at the fuel pump, the fuel pump on these cars are quite simple, they are either on of off, they are not regulated by voltage therefore the flow is constant. The problem with the stock pump is it can not keep up with the volume of fuel we are asking it to. When this happens we experience a drop in pressure at the rail at WOT. The numbers we were seeing were 54 psi at the rail during idle and 42 psi at the rail at WOT. At that point it became pretty apparent we needed a new pump. When you replace the pump it has to be replaced with a HIGH flow pump, it is important that it is able flow enough volume to keep up with the demands. Keep in mind the stock fuel filter is still being used, it has sufficient fuel flow characteristics to feed the system.
Next issue to address is the injectors. Remember as we add more air, we need to add more fuel. Since we just added a new high flow pump we now know we have sufficient fuel flow and pressure to the rail. Now how do we get the fuel into the engine, obviously it's via the injectors, so naturally we tell the computer to increase fuel flow through the injectors. The computer in return says "ok" and presto changeo problem solved, right? The answer is maybe...if you are running low to mild boost pressure you may be ok, but if you are running over 16 lbs ish you are probably running out of injector as well. This is why no matter what tune you throw at it it doesn't solve the problem. Although the computer is telling the injectors to add more fuel, they physically are not capable of keeping up with the demands that we are asking them to do. Even if they are able to "just" keep up, the duty cycle at which we are asking them to operate at significantly decreases their life span. So the solution as you may have guessed is bigger injectors, ones that can not only handle the volume but can also do it at a significantly lower duty cycle. This allows you some wiggle room with your tune to add more fuel if needed in the future. It also allows the injector to operate at a much more efficient rate and increases the life span of the injectors.
Moral of the story is, bigger pump, and bigger injectors are needed. Now you may be saying "in theory you may be right, but I think our cars have plenty of injectors and plenty of pump, the pressure is the problem. I think I'll just turn up the pressure to solve the problem". I will tell you with 100% certainty that that is not a solution to the problem, that is a band aid fix for a wound that needs a tourniquet. A lot of information that we have learned about this car has come not only from our race program but also from the SRT division of dodge/chrysler. I have talked extensively with a lot of the people who were involved with the development of this car. SRT is at our track quite frequently testing the Viper and I have the advantage of picking their brains while they are there.
Any question? Class dismissed!
Once we starting adding things like pulleys to increase boost this is where we run into trouble. As we add more forced air into the system we then need to add more fuel to the system in order to equalize the equation. You can't add one without the other. What most people do is add a pulley then get a tune to try to add more fuel. This combination will usually work if you are only adding only 1 or 2 more lbs of boost. In this scenario the stock fuel system is sufficient, but if you want more than 2 lbs of boost you start to ask a fuel system to do things it doesn't have the ability to do.
Lets start by looking at the fuel pump, the fuel pump on these cars are quite simple, they are either on of off, they are not regulated by voltage therefore the flow is constant. The problem with the stock pump is it can not keep up with the volume of fuel we are asking it to. When this happens we experience a drop in pressure at the rail at WOT. The numbers we were seeing were 54 psi at the rail during idle and 42 psi at the rail at WOT. At that point it became pretty apparent we needed a new pump. When you replace the pump it has to be replaced with a HIGH flow pump, it is important that it is able flow enough volume to keep up with the demands. Keep in mind the stock fuel filter is still being used, it has sufficient fuel flow characteristics to feed the system.
Next issue to address is the injectors. Remember as we add more air, we need to add more fuel. Since we just added a new high flow pump we now know we have sufficient fuel flow and pressure to the rail. Now how do we get the fuel into the engine, obviously it's via the injectors, so naturally we tell the computer to increase fuel flow through the injectors. The computer in return says "ok" and presto changeo problem solved, right? The answer is maybe...if you are running low to mild boost pressure you may be ok, but if you are running over 16 lbs ish you are probably running out of injector as well. This is why no matter what tune you throw at it it doesn't solve the problem. Although the computer is telling the injectors to add more fuel, they physically are not capable of keeping up with the demands that we are asking them to do. Even if they are able to "just" keep up, the duty cycle at which we are asking them to operate at significantly decreases their life span. So the solution as you may have guessed is bigger injectors, ones that can not only handle the volume but can also do it at a significantly lower duty cycle. This allows you some wiggle room with your tune to add more fuel if needed in the future. It also allows the injector to operate at a much more efficient rate and increases the life span of the injectors.
Moral of the story is, bigger pump, and bigger injectors are needed. Now you may be saying "in theory you may be right, but I think our cars have plenty of injectors and plenty of pump, the pressure is the problem. I think I'll just turn up the pressure to solve the problem". I will tell you with 100% certainty that that is not a solution to the problem, that is a band aid fix for a wound that needs a tourniquet. A lot of information that we have learned about this car has come not only from our race program but also from the SRT division of dodge/chrysler. I have talked extensively with a lot of the people who were involved with the development of this car. SRT is at our track quite frequently testing the Viper and I have the advantage of picking their brains while they are there.
Any question? Class dismissed!
1. Fuel pressure
2. Boost
3. Injectors
You have to address one of the three to prevent leaning.
1. Increase fuel pressure to counteract elevated boost on the injectors.
2. Reduce boost levels so you don’t need additional fuel pressure to counteract the effects elevated boost has on our injectors.
3. Get larger injectors to offset the elevated boost seen by the injectors.
The SL55 fuel pump does not increase fuel pressure enough to counteract elevated boost on the injectors because it is still governed by our filter/regulator setup.
2. Boost
3. Injectors
You have to address one of the three to prevent leaning.
1. Increase fuel pressure to counteract elevated boost on the injectors.
2. Reduce boost levels so you don’t need additional fuel pressure to counteract the effects elevated boost has on our injectors.
3. Get larger injectors to offset the elevated boost seen by the injectors.
The SL55 fuel pump does not increase fuel pressure enough to counteract elevated boost on the injectors because it is still governed by our filter/regulator setup.
As stated earlier we do not need to increase fuel pressure, we need to increase fuel volume and be able to maintain pressure. That is a huge difference. Also, if you only have low to mild increase in boost (2-4 lbs) a walbro pump should be sufficient. The stock fuel filter/regulator has suffecient flow charastics to supply an ample amount of fuel for most if not all engine modifications.
SSB SRT6 405hp/401Tq
THREE 6S
Join Date: Aug 2007
Location: From North TX..To SoCAL..Now Cnt Philly
Posts: 704
Likes: 0
Received 0 Likes
on
0 Posts
Re: datalogs LEAN AFR
Correct but the stock fuel filter/ regulator is replaced when adding an ADJ F/P Regulator. That was one of the conventional ways of thinking during those times.