[NumericalIntegration]

Like the title says, I get sporadic stumbling/misfires when at about 3/4 throttle or more. It tends to happen more at lower revs (2-3k). I can have INPA open in the passenger seat and get it to stumble/misfire but no codes show up. I recently replaced the intake VANOS solenoid and the #4 injector to fix previous codes. After I replaced these two it pulled cleanly as far as I can recall. Anyone have any suggestions or have expericed the engine stumbling but no codes being set?

The car is a manual 325i with 148k and a 3IM with the BimmerLabs 330i tune.

[Saico]

Usually misfires at lower revs + high load = spark problems.

[juld0zer]

reseat the ignition coils. Also ensure you have the correct spark plugs for your particular motor/DME.

[850CSi]

I'll start a thread of my own because I have a similar issue, my question to the two responders is wouldn't misfires or other coil/spark related issues throw a code?

[Saico]

Misfire code occurs only when misfires are permanent. DME has a misfire counter. It will not throw a code when misfire happens every now and then.

[NumericalIntegration]

Originally Posted by juld0zer

reseat the ignition coils. Also ensure you have the correct spark plugs for your particular motor/DME.

Tried reseating to no avail. I have Bosch FR7NPP332 spark plugs which are correct I believe. About 15k on them.

Originally Posted by Saico

Misfire code occurs only when misfires are permanent. DME has a misfire counter. It will not throw a code when misfire happens every now and then.

Is there a way to view a misfire counter for each cylinder through INPA or ISTA? I've tried looking but couldn't find anything.

[mrnuke]

Just went through this and replaced coils/plugs and all is well. BMW's enrichment is extremely good, so unless you're under high load/low RPM, they don't seem to happen consistently.

[The Nightman]

Originally Posted by Saico

Misfire code occurs only when misfires are permanent. DME has a misfire counter. It will not throw a code when misfire happens every now and then.

Yup. I was experiencing intermittent misfiring and did not get any fault codes or CEL until the coil had failed completely. Replaced all of my coils after as a precaution.

[gIzzE]

Reset all engine adaptations in INPA.

https://www.e90post.com/forums/showthread.php?t=1684489

[Silp3]

Cam position sensor. Pull out, clean off and check symptoms again.

[juld0zer]

Find a long hill and load it up. eg. put it into 3rd at 40km/h and floor the gas until the EML comes on. This will stress the ignition system.

Basic things first - is the oil level correct? Correct viscosity? Genuine or Mann filter? VANOS checkvalves clean?

[Mojoooo0]

I had the same intermittent issue. One day i put a heavy load on the car and was able to force a CEL to register which coil # it was.

My spark plugs were replaced under 40k km ago so i knew it was coils as all of them were not new.

I went up a hill with high gear, low rpm and forced the stutter/misfires and was able to get the CEL to stay lit. I replaced the one coil with a delphi one and so far its been good for 10k km.