[iSabir]

Hey guys! First time posting on the forums. I'm having a few issues with my car and wanted some input from you guys before I take it to my indy. I have a 2008 e92 335xi N54. Im fbo running Cobb AP with catless DP, FMIC, lower charge pipe, air intake block, and cold air intake. When im running the stock map, I don't have any misfire issues no matter how hard I push the car. When I flash stage 1 or 2, I keep getting misfires in cylinder 5&6.

I'm also experiencing a rough idle when I come to a stop and occasionally the engine will cut off. I notice this happens more then I'm pushing the car. Check engine light comes on when the car turns off, but when I start it again, it starts up fine and the light turns off. I took the car to the stealership and they told me it was the low fuel pressure sensor which is causing it, but even after I replaced it with a new one, I'm still having the same issue. I'm guessing that this might be caused by either a transmission issue, or carbon buildup. The car is an '08 with 55,xxx miles on it and has never had the intake valves cleaned. I'm hesitant to think that the misfires are caused by plugs/coils since I just replaced them ~7k miles ago in October of '15 and haven't driven it much with the tune since then. I've changed the LFPS, gotten vanos looked at, and gone through 4 bottles of Chevron techron and no luck.

February of 2016, the transmission dropped out of nowhere on my way home from work. I got the transmission rebuilt, but the car has never drove the same since. I can feel the transmission slip shifting from 1st to 2nd and occasionally from 4th to 5th.

Does this sound like something walnut blasting+new plugs/coils will fix? Or am I looking at putting in a new transmission?

[Jeff@TopGearSolutions]

Originally Posted by iSabir

Hey guys! First time posting on the forums. I'm having a few issues with my car and wanted some input from you guys before I take it to my indy. I have a 2008 e92 335xi N54. Im fbo running Cobb AP with catless DP, FMIC, lower charge pipe, air intake block, and cold air intake. When im running the stock map, I don't have any misfire issues no matter how hard I push the car. When I flash stage 1 or 2, I keep getting misfires in cylinder 5&6.

I'm also experiencing a rough idle when I come to a stop and occasionally the engine will cut off. I notice this happens more then I'm pushing the car. Check engine light comes on when the car turns off, but when I start it again, it starts up fine and the light turns off. I took the car to the stealership and they told me it was the low fuel pressure sensor which is causing it, but even after I replaced it with a new one, I'm still having the same issue. I'm guessing that this might be caused by either a transmission issue, or carbon buildup. The car is an '08 with 55,xxx miles on it and has never had the intake valves cleaned. I'm hesitant to think that the misfires are caused by plugs/coils since I just replaced them ~7k miles ago in October of '15 and haven't driven it much with the tune since then. I've changed the LFPS, gotten vanos looked at, and gone through 4 bottles of Chevron techron and no luck.

February of 2016, the transmission dropped out of nowhere on my way home from work. I got the transmission rebuilt, but the car has never drove the same since. I can feel the transmission slip shifting from 1st to 2nd and occasionally from 4th to 5th.

Does this sound like something walnut blasting+new plugs/coils will fix? Or am I looking at putting in a new transmission?

7K miles on plugs and coils should not be an issue.

However, I would at least look at the plugs and coils and see what they look like and ensure the gap is correct on the plugs.

Also swap coils 5 and 6 to 1 and 2.

55,000 miles on intake valves should not cause this issue, although they will be gunked up it should not cause that kind of issue. (Then again, anything is possible).

After you inspect plugs and swap coils report back.

Any other codes?

Which injectors are you on?

When was the last time your HPFP was replaced?

Also the reason this happens in upper gears and on a tune is because there is more boost and load on the engine, which means tolerances for inferior hardware is more apparent.

[iSabir]

Originally Posted by Jeff@TopGearSolutions

7K miles on plugs and coils should not be an issue.

However, I would at least look at the plugs and coils and see what they look like and ensure the gap is correct on the plugs.

Also swap coils 5 and 6 to 1 and 2.

55,000 miles on intake valves should not cause this issue, although they will be gunked up it should not cause that kind of issue. (Then again, anything is possible).

After you inspect plugs and swap coils report back.

Any other codes?

Which injectors are you on?

When was the last time your HPFP was replaced?

Also the reason this happens in upper gears and on a tune is because there is more boost and load on the engine, which means tolerances for inferior hardware is more apparent.

My indy is almost an hour away and closed on the weekends, so it's difficult getting in on the weekdays. I'm going to try going to see them within the next couple weeks.

I'm not getting any other codes, just for the misfires. Injectors are still stock, as is the HPFP. Indy diagnosed that there was a fuel pressure issue and it might be the HPFP. When I took it to the dealer to get it replaced under warranty, they said the HPFP was fine and I was getting the fuel pressure issue because of the low pressure fuel sensor, which I replaced to no avail.

[luckyblack]

In my opinion, your transmission is not causing your car to stall. You have a bad coil, fuel injector or fuel related part. As for the trans slipping, only you can tell. I have heard of bad engine parts causing a causing a slipping feel in the trans(like a bad fuel pump) but these transmissions are known to slip. If you have a manual you probably need a new clutch. Auto it could be torque converter, solenoids or something else.

[feuer]

You should have started first by posting info on your location and issues that you are experiencing before taking to a shop. Plenty on competent shops and individuals around Chicago that could have sorted this better and cheaper. Car need to be logged. Not only scanned for codes. Seems to me like your Indy is playing a guessing game and throwing parts randomly thinking and hoping it will fix it. Regarding the transmission rebuilt you were probably better off buying a used one instead. Either reply here with details or PM me. Good luck.