Another Miss-fire Issue

[Fleethammer]

New to this forum. Recently picked up a 2008 CPO 135i with 25K on it, one owner, clean Carfax, all recalls performed. I have good technical knowledge of cars and consider myself technically competent. The only mod I have installed currently is a Cobb stage one 93 aggressive map.

Like may other 1er owners, I'm having the miss-fire/limp mode issue when getting on the throttle. When accelerating hard, the car will begin to shudder at higher RPMs before the CEL comes on and massive power loss occurs. Sometimes the limp mode is accompanied by a "pop" other times it just shudders it's way into limp condition. Reading the codes, I typically get misfires in one or two cylinders, sometimes in more than one cylinder!

Reading all the threads out there, this could be an issue with plugs, injectors, or coil packs, among other things. I couldn't find anything wrong with the car after a visual inspection, so I uninstalled the Cobb tune and made an appointment with my local dealership.

Right away the dealership is able to see the codes stored deep in the ECU relating to the misfire condition. Unfortunately, they won't do anything about it. According to them, BMW's test plan calls for them to clear the codes and give the car back to the customer, no further testing of injectors or coil packs, don't even check the condition of the plugs. I'm not certain if this is correct, or if they simply don't want to test anything to find where the fault lies, but the SA is telling me that BMW's position on misfiring is that it is not serious enough to warrant diagnosis or repair. As long as it is running fine when the car is brought in, the car goes right back to the customer period, end of story. This is ridiculous since the car will ALWAYS be running fine when I bring it in since I have to re-start it to get out of limp mode.

Since the issue occurs when merging into traffic, or passing another car, I ask the SA "what if it happens again?" to which he replies "just shut the car off and restart it like you did last time." He also recommends "not accelerating so hard". I find this unacceptable on so many levels. It's like saying if second gear is broke, just don't use second gear because you have four other gears.

I want to mention that since the new Cobb v301 stage 1 maps, the car no longer goes into limp mode, but I still get consistent misfiring under hard acceleration. So there has been improvement, but the problem is not solved.

Any recommendations on what to do here? Should I try another dealership? Sadly, this is the "better" of the two dealerships in my area. The other one is nearly incompetent. I don't want to be stuck with this problem for as long as I own the car because BMW won't find the cause of the problem. I want this taken care of before moving ahead with future mods. I have an IC and DCI waiting to be installed

Thanks for your help guys!

[FJUNO78]

Did the car behave this way prior to the tune?

[Fleethammer]

No, only with the tune. It runs fine when back to stock.

Originally Posted by FJUNO78

Did the car behave this way prior to the tune?

[FJUNO78]

So you want the dealership to troubleshoot a problem caused by a tune, without letting them know the tune even exist.



I think you really are being unrealistic. this is an issue you have to sort out with COBB.

[f1rst 1]

I had the exact same issue, I swapped plugs around, and the misfire always followed the coilpack. Replaced a coilpack for 45 bux from the dealer and the problem was solved. Haven't had an issue since, new or old maps.

[Fleethammer]

Pretty sure the tune doesn't cause the issue; it's revealing or exacerbating a design flaw in the fuel/spark delivery systems (a bad coil pack for instance). A modest horsepower increase shouldn't make the car shut down, especially if most other 135 owners running the same tune aren't having the same problem. I haven't seen any case where a stage 1 tune has required upgraded coil packs or injectors yet. There is something wrong with the car that would become more apparent over time if I ran the stock tune; the Cobb tune is making it show up sooner than later.

[prodigal_m]

Originally Posted by Fleethammer

Pretty sure the tune doesn't cause the issue; it's revealing or exacerbating a design flaw in the fuel/spark delivery systems (a bad coil pack for instance). A modest horsepower increase shouldn't make the car shut down, especially if most other 135 owners running the same tune aren't having the same problem. I haven't seen any case where a stage 1 tune has required upgraded coil packs or injectors yet. There is something wrong with the car that would become more apparent over time if I ran the stock tune; the Cobb tune is making it show up sooner than later.

It's coils, sparks pulgs or both. You are about at that mileage where your plugs should be replaced anyway. It's probably just a coil or two...replace and enjoy.

[FJUNO78]

30% increase in HP & 40% increase it tq is far from "modest". Infact, in the first post you said it was "aggressive"


I think it is a stretch to say you are suffering from a potential design flaw... your car is already 4+ years old, you probably need new plugs anyway. Try that first.

[ken1137]

Based on similar reports it probably is the plugs or the coil packs as other have stated. Keep in mind...those that dont use a tune or Cobb A/P will always give you shit about whatever problem you are experiencing and blame the tune. Correlation is not causal.

[Fleethammer]

Thanks for all your help. I guess when I say "modest" I'm referring to numerous build threads where coils and injectors were not replaced until very high horsepower levels were reached. Comparatively speaking, Cobb stage 1 is pretty modest, considering it is intended for bone stock cars with no supporting modifications. So whether it is a design flaw or the parts are just getting old, it would have been nice for the dealer to diagnose the problem and replace any needed parts under warranty. A bad coil for instance, will eventually fail, tune or no tune.

I'll try the plugs at $20.00 each . If the problem persists moving coils around will be the next step.

Originally Posted by FJUNO78

30% increase in HP & 40% increase it tq is far from "modest". Infact, in the first post you said it was "aggressive"


I think it is a stretch to say you are suffering from a potential design flaw... your car is already 4+ years old, you probably need new plugs anyway. Try that first.

[FJUNO78]

Originally Posted by ken1137

Based on similar reports it probably is the plugs or the coil packs as other have stated. Keep in mind...those that dont use a tune or Cobb A/P will always give you shit about whatever problem you are experiencing and blame the tune. Correlation is not causal.

I have tuned / modded several cars throughout the years. I am not giving him "shit". I am just stating the obvious. Grow up.