[gregsatt]

2011 335is

JB4 running map5

Took a 600 mile road trip and didn't have any trouble. Got up the next day and it started right up but was idling VERY rough.

Found misfires on 2 and 3 and also got a 29F3 which is Fuel Pressure Sensor Electrical, 2AAF - Fuel Pump, Plausibility, and a 29CC - multiple misfires.

The plugs and coils are only about 6 months old. I usually run 3-4 gallons of E85 mixed in with Super (93 octane).

Any thoughts on what this could be or what and how to test anything?

[AM330i]

you can swap the coils to another cylinder to see if the missfire follows the coil. if it does, you have a bad coil, if does not follow it is something else. when my hpfp was bad, I would get a missfire and ck eng light when I start the car in the morning. it also did this when I had leaking injectors.

[gregsatt]

Thanks. I'll try that.

Originally Posted by AM330i

you can swap the coils to another cylinder to see if the missfire follows the coil. if it does, you have a bad coil, if does not follow it is something else. when my hpfp was bad, I would get a missfire and ck eng light when I start the car in the morning. it also did this when I had leaking injectors.

[MadToy]

Do you run your tank empty before filling the e85 mix back in? If not, and you continue mixing in 3-4 gallons, it's possible you're just running too much e.

[gregsatt]

I'm careful not to put too much. I will run 4 gallons, run it empty, then only put 3 to 3.5 in the next time, then usually go back to 93 for a few tanks...

Originally Posted by MadToy

Do you run your tank empty before filling the e85 mix back in? If not, and you continue mixing in 3-4 gallons, it's possible you're just running too much e.

[MadeInPhilly]

I recently replaced injectors, plugs, coils, and O2 sensor. Code 29F3 still remained after clearing the misfire codes. I ordered the new Low Pressure Fuel Sensor with the hardline assembly. I actually think it was the 29F3 all along cause I didn't find my plugs to be too bad.

[TDI_G]

I had bad misfires on start-up and sometimes it would randomly start missing until I would turn off and restart the car. I first replaced plugs and coils and everything was good for a few days and it started up again. In the end, I had two injectors that were leaking and a weak HPFP. I went ahead and replaced the low pressure fuel sensor while I was doing the HPFP. No issues since.