Good afternoon everyone,
I have 05 base crossfire, with just over 400,000 miles. It's in pretty good condition. I have performed all the needed work myself, so I pretty much know what has been done. I'm having an issue with misfires at high speeds and high speeds only. The car drives fine under 85 miles per hour. I mean absolutely fine. The DTC or the same every time, P0302, P0305, P0306, P0300. I have changed plugs, wires, coil packs, CPS, Cam Position sensor, new battery, harmonic balancer and seal, & serpentine belt. MAF was changed less than four months ago. EGR valve changed about a year ago. All parts the recommended parts from the members of this forum (Bosch, Needswing parts) except the MAF. I have performed a vacuum test fine. Held steady between 17 and 21. Compression test fine. Every Cylinder at about 178. Fuel pump and fuel filter was changed less than a year ago. Test the fuel pressure and it was fine. Replaced intake manifold gasket ensured it was properly aligned.


That being said what could I be missing besides the Cats, bad MAF, or is it a bad ECU? Any suggestions will be greatly appreciated, except get rid of the car.

 

I see everything that comes to mind in your list, except maybe injectors .....
( I certainly hope it is not an intermittent open condition in the wiring caused by vibration )

 

With a misfire happening on both banks I'd be looking at the MAF, MAP, and TPS. Those DTCs are standard OBD-II, for an in depth look it takes something that can scan the extended Mercedes codes. e.g. an Autel or iCarSoft scanner with BENZ module or a Star/DAS dealer scanner.


Can monitor & log the relevant parameters with an Android phone or tab, a cheap OBD-II dongle and Torque Pro ($5)

 

Hey guys, thanks a bunch for the responses. I have an android phone and will look into the dongle and Torque Pro. I left out the injectors, but they are new. I going to change the MAF and MAP. As for the TPS I have 74mm throttle on now, but still have my original throttle. I will swap it and see what happens. I'm going to perform a back pressure test to see if the exhaust has any blockage. I certainly hopes it's not wiring also. Thanks again for the responses and will keep the post updated as I work through this to find an answer and I will update with the resolution.

 

I feel confident that you will from the level of knowledge evident in your posts.

 

Since your problem is ONLY related to what speed the vehicle is going and not the speed of the engine that does rule out a bunch of typical car related problems.

The only thing that I can think of driving at higher speeds would be vibrations... something is wiggling at that speeds when its not supposed to.

Does the car drive ok at that speed? Or does it just throw a code going above those speeds?

Maybe try when the car is idling to wiggle "GENTLY" on some of they key components and see if you can recreate the problem that high speeds would cause. like the MAF or injector connectors if you can get to them. Possible the ignition components as well.

Since its multiple cylinder misfire Probably not going to be specific cylinder related issue so I would check main components first, then head down to individual things like spark plugs and injectors.

Hope it goes well!!!

-Darren

 

If I had not seen what was replaced I would have said fuel starvation was the pump changed because of the misfire or before? Correct fuel pump that is up to the cars required spec?

 

Hey guys, you do not know how much appreciate the responses. It very well could be the vibrations at that speed and I will attempt to wiggle some components to see if there's a change in the idle. It drives fine until around 85mph. I've even went to WOT from around 20 mph and it did not misfire. I awaiting a new MAF and MAP and will update once I replace them. I performed another vacuum test, this time looking for back pressure. According the test, there was none.


Here's the fuel pump I purchased in May 2017 from fcpeuro.
Mercedes Electric Fuel Pump (300CE 400E 500E) - Pierburg 0004707894
I could not find where I purchased the fuel filter. I think I purchased it local. It was a Mahle. Could it be the filter? I purchased a cheap one on rockauto and it destroyed a fuel pump. When that happen, the pump hummed really loud and the car would stall when I came to a stop.

 

Isn't ANYONE going to comment on the "just over 400,000 miles" in the post?
This is, I am sure, the forum record.

 

Alright just for you guys. Bought it brand new July 2005. Always in the garage, but it has always been my daily driver. Around 50,000 miles sticky ignition and you guys got me through that! It was my first time on the forum. Next at around 100,000 CPS, Plugs and wires. Around 120000 accident. Had to get new exhaust system insurance paid. P0410 was going on for about 4 years. Finally bought a pump from a member on this forum (you guys are the best). Around 200000, all hell broke loose. Literally! Motor mounts, 2 Clutches, ESP/BAS light, crankcase breathers leak. A/c condenser, A/c compressor, Evap and Dryer. All the work done was by myself with help from you guys on this forum. Except the clutches. Nothing really major after that. I do not consider any of this major, due to the fact that this is a hell of a car and you guys are the best at assisting any one who needs help. Besides normal consumables i.e., brakes, shocks, oil and interior parts I can not say the car has put me down for long. Except once. A was hit in the rear and it broke the drive shaft flange to the tranny and it had to made in Germany. I had to wait 30 days while a local shop order it. Don't know if that was a load of you know what or not?

 

Where are you located ?
You must have one hell of a commute

 

I'm in Jonesboro, Ga and I commute to Lilburn, Ga everyday for 14 years. I had a VW New Beetle when I first began. Wore that thing our pretty quick. ))

 

Traffic, traffic, traffic.
I did Stone Mountain to Duluth for 20 years in an '81 Mazda 626 manual and had only ONE accident !
( not my fault )
Thank God that's all over with now.

 

Alright, here's a quick update. I performed another fuel pressure test. My gauge broke (Bosch). Bought a new one. Performed an ignition, idle and tried to perform a fuel capacity test. That's were things got kinda interesting. I have released the fuel on the system very recently. Like about a week ago. Released it fine. Change fuel injectors. No problem. Today I could not release the fuel. Removed fuel filler cap, remove fuse #5 RCM, press release pin on the fuel rail. Car continue to crank several times and run momentarily until finely only attempted to run. Go back to fuel rail, press pin on the fuel pressure test port. Fuel continues to pour out. Okay attempt to remove fuel line at the rail. Fuel squirts out with high pressure. Okay, reading on the gauge at idle was 60psi and manual states if the psi is above 54 it's a bad filter/regulator. Could all my trouble be a D&*% filter. I know I seem mad, but if it is I will be happy as H-LL.

 

Well, the filter does determine the fuel PSI by means of a spring and valve, so it could well be the fox you are looking for in this hunt. Pretty cheap fox too.

 

I mean for something very cheap and easy to replace I suppose you could do that and see what happens.

I'm just trying to figure out why that would be a SPEED related issue. I mean if you're getting misfires from fuel problems, doing WOT runs would FOR SURE make the car run bad. Not just going over 85 MPH.

Could possibly be a computer related issue? No idea.

Keep us posted on what you find hahaha

 

Okay, just to let you guys know I will not abandon the thread. I will update. First, I bought another crossfire. 06' roadster, 110,000 miles. It seems to be in pretty good shape. I don't know though. I'm not afraid. We've got the forum .
Well, I replaced the MAF and MAP. High RPMs at stops, gone. So I'm thinking it was a MAF issue. I had a Bosch for FCPeuro and it failed. I tried to exchange for a new bosch, but they just refunded me. So I need a MAF and I went to Autozone. Yep! Durlast won't LAST. Any who, the new bosch works great. I don't know if the MAP did anything, but the car runs smoother. It's still misfires. I'm leaning towards the cats. I going to keep working at it. I plan on changing the exhaust anyway. 401,954 miles, every time I change something the car runs better. So I look at like this it needed anyway.
Will, keey everyone posted and If I find the problem I definitely will update!

 

Okay, I'm back. I purchased this Foxwell scan tool from amazon for about 37 dollars. It's okay. Not the best, but it does work. I collected some real time and freeze frame data. I've been looking at the fuel trims and long and short term are negative. At 3275 rpms, 93mph, TP 100% Long term was -96. Could the upgrade mods (fuel injectors and throttle body) be causing the ECU to turn of the fuel injectors. Please don't yell at me, I'm out of my knowledge range and am willing to learn. I can post pics of the freeze frame data and the live data if need be.

 

As promised I would post the resolution to my problem. I had almost resolved to having a crossfire that would misfire at high speeds/WOT. I noticed water drops that appeared to be some type of coolant leak and was spraying the engine compartment. I could see it on the secondary air pump bracket, the oil filter housing, but not the thermostat. I did not want to think it was the coolant temperature sensor, but it was leaking due to the o'ring and it has 403,000 miles on it. I had never changed this sensor. I change the sensor and at first it misfired again under load. I thought oh well. I left the check engine light on. The next morning instead of taking the roadster I decided to take the coupe and what do you know. I started it up and let the secondary air pump switch off and then drove off. About mile down the road I noticed the MIL was out. I decided to attempt to cause a misfire. 100 miles and 110mph later I'm glad to report no misfires.


I did a bit of research and found that the ECU adjusts the fuel ratio mixture according to the temperature of the engine, which is read from the coolant temperature sensor. Easy $17.00 fix. Only takes about 20 mins if that.


Jack car and secure with Jack stands
Connect 3/8inch(I think) hose to the radiator drain nozzle
Place the other end of hose in a 2 gallon plastic fuel container
Open radiator drain plug, let drain until it stops. (for me about 1 1/2 gallon) Close drain plug.
Disconnect hose.
Disconnect electrical connector to coolant temperature sensor
Remove clip from sensor with flat head screw driver by prying upward
Pull sensor out and do not forget to remove and replace the o'ring.
Install in reverse order.


Reuse coolant by simply pouring it back in the overflow tank. It should all return.

 

Wow!
403,000 miles, that has to be a record.
Thanks for the reply, I will add this to the index of problems and fixes..