[AndyR83]

Hey guys,

My car is acting a bit funny under specific, reproducible circumstances. I have a couple of theories, but I'd be interested in hearing what others think may be the cause.

I don't flog my car on a regular basis, but sometimes on a lonely, deserted road at 3am, I do like to see what it can do. I have observed on several occasions that pushing the car very hard results in a check engine light.

Situation 1: Pushing the car very hard on the highway has about a 50% chance of causing a yellow half engine light. This also includes "limp mode." Restarting the car clears the error immediately, and normal performance is restored.

Situation #2: "Launching" the car in DS mode and performing manual shifts (always around 6k, not deep in the red or anything) has about a 50% chance of causing the yellow "service engine soon" message to blink on and off for a few minutes. This does not trigger limp mode, and the light goes away after blinking for a little while.

I theorize that one of three things are the culprit.

1: The oil filter is crappy and restricting oil flow, potentially leading to an oil starvation situation. I was once told by the dealership that the oil filter they found when they did my oil after having had an indie shop do it the previous time was very poor quality, and had disintegrated causing poor oil distribution. I'm about due for an oil change, and I had an indie shop do it last time. It could be another low quality filter that is falling apart in there again, and preventing adequate oil flow.

2: The spark plugs haven't ever been changed, and I'm at about 53k miles. I thought this may be a misfiring issue. I intend to swap out the old plugs for new ones next weekend.

3: The valves may be in need of cleaning. I am looking into getting walnut blasting done, but was curious if this might be contributing to the issues.


Important background data:
The car is a 2008 335i base model

It has a JB4 tune running Map 5, though I also identified these symptoms when it ran Map 2 previously.

It has a BMS speed delimiter, but the crank position sensor is not hooked up (I folded it back on itself and covered thoe specific wires with electrical tape at time of install)

Other mods include catless DP's, FMIC,

Thanks in advance for any insight you may have.

[AndyR83]

As an adendum to this, let me also say that I do not have auto code-clearing enabled in my JB. I also do not have the USB cable to plug into it unfortunately.

[Ænema]

Without codes it's hard(nearly impossible) to give any solid advice.
The top two most likely culprits are 1) a boost leak 2) the normal tune induced misfires(see the sticky at the top of the first page)

[pits200]

Ya, you have to log to see whats going on with boost.

1.) Leaky valve cover causing oil to cake the plugs and having you misfire at wot and high boost.

2.) Check to see if it happens on stock boost also

3.) Check to see if the limp is from underboost condition and not a misfire.

[ragingpanda]

We need codes!

Up, down, left, right, A, B, start.

[krazyking]

Need codes as other said. But deff get your spark plugs changed. Esp since you are FBO, its about time..

[Rotorocious]

advice. get that damn cable

[AK 335i]

change plugs anyway. get the cable installed and start logging. you and your dad will become fridges

[cn555ic]

You need to learn how to use INPA to read the codes as you already have the Dcan cable...Without codes this thread is basically useless.

[AndyR83]

Sorry for the stupid question, but is it possible to read codes without the JB4's USB cable? Meaning, can they be seen on the dash or anything? The cable is dirt cheap but I loathe taking the cowl apart to access the ECU compartment. I can never get that damn thing lined up on there properly when I'm trying to reinstall it.

I do have the OBD2 cable for coding. Anything I can do with that?

[Leekay07]

I say you need to replaced some injectors then replaced plugs and clean valves. (replace the plugs on the worst valves)

[MilehighM3]

You crank sensor wires are tied back? That sounds like a good place to start. Remove your tune and see if the faults return. It may be install related judging by the "expertise" you showed in your initiation of yet another thread without any technical data.
Your car is under maintained, get it up to date with the right parts. Then, pay someone who knows what they are doing to diagnose the car. People on the Internet can throw out ideas that they read in previous threads that don't pertain to your car, and that gets you no where!

[cn555ic]

Originally Posted by AndyR83

Sorry for the stupid question, but is it possible to read codes without the JB4's USB cable? Meaning, can they be seen on the dash or anything? The cable is dirt cheap but I loathe taking the cowl apart to access the ECU compartment. I can never get that damn thing lined up on there properly when I'm trying to reinstall it.

I do have the OBD2 cable for coding. Anything I can do with that?

Wow do you actually read peoples post?? I stated if you have the coding cable, YOU CAN USE INPA...

[raceyBMW]

Read your codes, but what you are explaining sounds like it could be a vanos solenoid issue or any of what the others stated. When throwing CEL's always check codes first and go from there, it will make things easier rather than being a guessing game.

[AndyR83]

Originally Posted by cn555ic

Wow do you actually read peoples post?? I stated if you have the coding cable, YOU CAN USE INPA...

Yeah, your post is the one that prompted me to ask o.o I was looking for clatification.

Originally Posted by Bmw135er

You crank sensor wires are tied back? That sounds like a good place to start. Remove your tune and see if the faults return. It may be install related judging by the "expertise" you showed in your initiation of yet another thread without any technical data.

The install instructions supplied by BMS clearly stated that the speed delimiter and CPS could be installed independently of one another by tying back the wires for the one not being installed. My thread included all the technical data available to me at the time, no need to bash someone for not owning a piece of diagnostic equipment. Sounds like I can try using my other cable to get the info, though.