CEL and limp mode E92 M3 (typically after fill up)

[Alpinev8m3]

Hi everyone, first post here on the forum. I tried to look for similar situation before posting, but I have yet to find something.

Here’s my situation, recently purchased a 2008 M3 6spd. Car has 117,000k miles. For PPI done with clean bill of health and maintenance records. The car has X-pipe, Bomiz Valvetronic, and gintani tune.

The second day I owned car, while driving normally I got a check engine light with reduced power and limited RPMs to 4.5. The car would idle at 1000 versus below as usual. I ran the codes for when I got home and it showed a misfire on every cylinder.( P0 codes). I thought that was odd, and figured no way it could be misfiring on every cylinder. Sure enough turn the car off and back on and it’s gone, no issues.

I brought it to a local BMW performance shop where they did a diagnostic said the car was completely fine, no mechanical or electrical failures that they could notice from the first inspection.

I continue to drive the car with no issues, however, today again same thing this time the codes showed only misfire on cylinders 1-4. Turn the car off, read the codes, turned back on, car is back to normal.

Now, the only commonality between the two occurrences is each occurred shortly after having the car get to E on gas and then filling it up to full (when the pump stopped I stop, I don’t keep filling it). The cars gas light comes on at a quarter of a tank, I don’t purposely try to run it until the gas light comes on, but just take some getting used to.

With that being said, would love to get some insight, if anyone else has experienced this, and or what it could be? Is this particular to the tune? Or or one of the other known issues like fuel breather valve, throttle, actuators, idle control valve, etc. Is this cause for concern?

[Redd]

Did the shop scan the ecu for stored codes? Did they check the ground strap at the front near the driver side header? Worn ground straps can cause weird issues.

[Alpinev8m3]

No stored codes, they checked. But not sure about the ground strap. That’s a new one for me.

[Tommysalami]

If it's after filling up, a common failure is the fuel tank breather valve. Could be the culprit and is cheap and easy to replace

[veovo]

Air in the fuel tank?

New cars get CEL if fuel cap is not tight. Not sure if E92 has this

[jmeenach]

I'd also say FBV. Can you smell any fuel in the cabin after fuel up? Are the RPM's just higher or are they uneven?

[Alpinev8m3]

Hey everyone, update: has not happened since, I simply do not let the low fuel light come on. I did purchase the fuel breather valve just in case, and will install that. Most professionals I have spoken to thinks it is attributed to the gintani tune, for whatever reason.

[DrFerry]

Fuel Tank Breather Valve or failing Throttle Actuators or both. Check the service records to see IF the Throttle Actuators have ever been replaced.