Now that we have Eurocharged, Code3, LET and Needswings all making great parts for our car, how about we address some basic issues. FUELING I have seen several cars hitting the dyno and running lean including me. How about some fixes, like injectors that fit and can be calibrated with dyno results of 12-12.5 air fuel ratio's or boost-a-pumps like kenne-Bell. Since everyone likes to sell the HP making parts shouldn't the lack of fuel already have been addressed. Maybe a new fuel pump and injector package. Nobody gives a definite answer to the fueling question. Is the stock pump up to the task with bigger injectors, or will bigger injectors not work because the factory pump can't flow enough? Since these companys are selling products that can get you to run lean how about we fix that issue, then see what the next level will be. Thanks

 

Some of this is caused by the back pressure of the extra boost.
Woody came up with a work around for this.

 

Actually he added the boost pressure back into the pump and ran 10:1 pig rich not really a tuning solution.

 

Here is a thread on Determining maximum horsepower supported by fuel system.

I hope that makes sense. Basically if the tuner can alter the pulse width, then they can make the fuel ratio more rich. And nobody here should need larger injectors. If the tuner does not have the ability to alter the pulse width, then the easy way to get a richer ratio would be to pick a set of slightly larger injectors. Then the pulse width would increase the richness of the fuel ratio.

 

i believe we are all working on them now already

 

The injectors are only adjustable to 86-90% duty cycle then they go static. I was going to go bigger injectors BUT nobody seems to know for certain if the pump is up to the task. This problem has been floating around for quite some time and I feel it should have been resolved. I don't have the software for adjusting the injectors, plus that graph doesn't have how many lbs of fuel/hr or loss from restriction in the pipe path. You need to have the correct amount of pressure and the correct amount of flow, when under full load bigger injectors won't help if the fuel rail doesn't have enough fuel

 

Excellent how about a question?? Can the stock pump handle 60/lb injectors

 

I thought i already proved the stock pump was weak. The Walbro 255 was able to hold higher fuel pressure in the top of 3rd.

The main thing i keep saying is you have to realize the stock fpr/filter will ALWAYS limit the fuel pressure to 54-60psi. This is why the boost-a-pump as well as the Walbro 255 are limited...the fpr bleeds off the extra pressure.

A return style allows for the pressure to be raised but at the expense of having too much fuel in the midrange rpms. As ive stated before we need the ability to tune ourselves. But im not gonna hold my breath on that one.

Now what would happen if you had bigger injectors but the same fuel pressure, could you get by w/o having a return style? You would still need your tuner to scale the injectors to the ecu...and you might need more than one map...once again, self-tuning is the answer.

 

How did you prove the stock pump was weak, I get the pressure being bled off, but if the flow is there you can still calibrate the injectors. I was told there was enough fuel but the injectors go static after 86-90%. Remeber you are not running the 60lb injector full open it will be at 80% duty cycle to handle the fuel needed, not that far past the factory unit. According to the info on the pierburg pump it is suppose to support more then what we are making.

 

Some will have noticed my diminished activity, well the front end got done and the adsorbitive front coating is now complete.

hood finished, bumper painted and back on. Photos to follow.
I have have been doing the electrical thing with my battery design, should have results in about a week if my designs work out.

Now the present:
The fuel. Injectors, nuclear fuel pumps, Ionic foam air filters, black light headlights...........Nothing is going to fix the fuel mixture issue...............NOw that is a strong statement.

The fuel map is a set of numbers that describe a curve controlling or administration the duration or open time of the injectors. It is correct some where, like having a broken watch, good twice a day........... The curve is approximately good and servicable for the most part but is not correct or accurate, its in the region of reasonable, butt just inthe 'hood'.

If you have more capacity added in the fuel pump or bigger injectors then the curve will allow more fuel EVERYWHERE. What we must do is add more here and less there and that VARIES with the DA, the boost, the humidity, fuel, your fuel map, and mods to your intake, exhaust, etc.

In my previous efforts I found that my cars fuel pump - pressure was flowing too little and I was going TOO lean , 17 to 1 lean above 20 psig. I then added controls to adjust the boost according to my A/F readings while I was driving and got closer to the 12-13 range. I ran out of control because with no additional fuel pressure I was too rich below 17PSIG and lean above 20 PSIG, cause my pump was too frisky below 17 PSIG, I could not pull back enough.

I now have a FPR to be added next month that is adjustable and tuneable with the application of vacuum or boost to change the fuel pressure down or up. I feel that the fuel pressure will be the way to control the F/A ratio --as the car needs it to CLOSE THE LOOP dynamically while your driving.

THis will be taken up next month after the light weight battery study is over. If Iam successful, then I believe that the car can be set up to give a specific F/A UNDER LOAD as you drive.

I have already proven that the fuel pressure if raised by less than 5 PSIG you can correct lean under boost to rich, though it is TOO much of a hammer, ie too big a change.

I am still working onthe design but have had lots of stuff besides cars thats slowing my progress, more light in the afternoon will assist.

Have a great weekend. WOODY

 

[quote=waldig]Some will have noticed my diminished activity, well the front end got done and the adsorbitive front coating is now complete.

hood finished, bumper painted and back on. Photos to follow.
I have have been doing the electrical thing with my battery design, should have results in about a week if my designs work out.

Now the present:
The fuel. Injectors, nuclear fuel pumps, Ionic foam air filters, black light headlights...........Nothing is going to fix the fuel mixture issue...............NOw that is a strong statement.

The fuel map is a set of numbers that describe a curve controlling or administration the duration or open time of the injectors. It is correct some where, like having a broken watch, good twice a day........... The curve is approximately good and servicable for the most part but is not correct or accurate, its in the region of reasonable, butt just inthe 'hood'.

If you have more capacity added in the fuel pump or bigger injectors then the curve will allow more fuel EVERYWHERE. What we must do is add more here and less there and that VARIES with the DA, the boost, the humidity, fuel, your fuel map, and mods to your intake, exhaust, etc.

In my previous efforts I found that my cars fuel pump - pressure was flowing too little and I was going TOO lean , 17 to 1 lean above 20 psig. I then added controls to adjust the boost according to my A/F readings while I was driving and got closer to the 12-13 range. I ran out of control because with no additional fuel pressure I was too rich below 17PSIG and lean above 20 PSIG, cause my pump was too frisky below 17 PSIG, I could not pull back enough.

I now have a FPR to be added next month that is adjustable and tuneable with the application of vacuum or boost to change the fuel pressure down or up. I feel that the fuel pressure will be the way to control the F/A ratio --as the car needs it to CLOSE THE LOOP dynamically while your driving.

THis will be taken up next month after the light weight battery study is over. If Iam successful, then I believe that the car can be set up to give a specific F/A UNDER LOAD as you drive.

I have already proven that the fuel pressure if raised by less than 5 PSIG you can correct lean under boost to rich, though it is TOO much of a hammer, ie too big a change.

I am still working onthe design but have had lots of stuff besides cars thats slowing my progress, more light in the afternoon will assist.

Have a great weekend. WOODY


I'm pretty sure Wayne at LET told me you can scale the maps down to make larger injectors work. The larger injectors are 20% larger and are supposedly still within the calibration limits of the ECU.

 

This was attempted on airfrcd's C32, with less than stellar results:

http://www.mbworld.org/forums/c32-am...more-come.html

YMMV, however.

 

Thank you for the information, This was done in January, and Wayne told me in the end of February that bigger injectors would work, apparently Wayne already tried this and knows it doesn't work. I'll take this up with him directly. Thanks again

 

Even with the fpr/filter eliminated the stock pump would not hold the desired fuel pressure to redline with the return style setup. Swapped to the Walbro and it held just fine.

 

Pressure always drops off. What did the pressure read and what was the flow rate?
Two Possible solutions:
1. A Kenne Bell Boost a pump will add additional fuel at a preset amount of boost, 3 or 5 lbs. This set up works but needs to be adjusted for by the tuner. Code3 has used this set-up with good results.
2. 20% larger injectors. Dino, a tuner in California, has done this set up on SLK 32 AMG's and it has worked. He says that the factory pump is enough.
I know it gets confusing because everyone always talks about pressure but to much pressure from the pump isn't good either. One - it opens the FPRV, two- it can cause the pintel in the injector to slow. When the pressure drops off, the pump increases flow. The amount of flow will then determine if you have enough fuel to tune with. The KB set up works because when you approach high rpm's, the injectors take away alot of the pressure in the rail, the BAP supplies 12-20volts to the pump at this time to spin it faster, and flow is greatly increased. If you were to try and snap shot the pressure it would proboably be higher then 60 pounds. It is running basically unrestricted because of the rpm's and rapid injector firing. With the above link the car was untunable not due to the injectors but to the fact that both pulley's go out side the MAP calibrations because of the boost levels which creates a a different set of problems. The car is now running fine with the 185 pulley and bigger injectors.