[mrvedit]

Looking for advice on a strange misfire problem...

While I already have a 335xi, I am considering another one (a 2008 335xi 77,000 miles) I found at a low price at a used car lot. The seller seems to be a straight shooter and I learned he bought it from a bank and it is therefore likely a repo and maintenance may have been marginal. Overall the car is in good shape for the price.

The seller replaced the battery himself (hmmm) and knows nothing about these cars.

On the test drive, as soon as I briefly went WOT, I felt a vibration and the Service Engine Light turned on. The vibration continued and felt like a serious misfire. After slowing to a stop, the vibration stopped and the light turned off. After another brief WOT, the vibration and light returned. This time the problems remained until I parked and restarted the car. Then all was well again, presumably until the next WOT.

I understand that a WOT misfire could be caused by bad plugs, wires, coils, injectors or fuel filter, but why would the misfire continue until a restart? Unfortunately I forgot to take my code scanner with me and the car lot is an hour away.

If this is likely a well-known easy-to-fix problem I may decide to give the seller a low-ball price as he knows he cannot sell the car as-is and is afraid to take it to a BMW dealer/shop as that might reveal other problems he would have to disclose.

If people here don't think its serious, I will take my code scanner and check it out more thoroughly.

BTW - It also has a flakey driver's side window. Probably the switch?

All feedback and ideas are appreciated.

Thank you.

[mrvedit]

Since the seller did not register the new battery he installed, I am trying to determine how many of the "new" problems that started after the battery swap might be due to that. I doubt the misfire is due to that.
Anyway I ordered both the Wifi and Bluetooth OBD2 dongles and will purchase the Carly-For-BMW app onto my Android or iPhone. Hopefully that will let me reset the battery and determine the code(s) related to the misfire. I might be able to get this car for under $12K.

[IN54NITY]

Impossible to tell without looking at the codes. I think you simply have to bring your code reader along and check those out. It could be as simple as replacing (or even just cleaning!) the VANOS solenoids or anything you mentioned. I don't know why the SEL would turn itself off, certainly the codes would remain.

http://www.e90post.com/forums/showthread.php?t=806694

Also, you might want to post in here: http://www.e90post.com/forums/forumdisplay.php?f=58 That forum section gets a lot more eyeballs.

>It also has a flakey driver's side window. Probably the switch?

Possilbly or the regulator - when the cable starts to wrap around badly it will act inconsistently. Take your pick.

[mrvedit]

I went ahead and bought the 335xi (my 2nd) from the used car lot. Price was $1000 below the KBB private party sale. Having the dealer handle the paper work was a nice bonus.

Using Carly for BMW it started with 30+ codes. After clearing them I have 5. The most significant is: 029F3 Fuel pressure sensor.

Reading the threads here on 029F3, several people report getting misfires at WOT just like this car. And they sometimes keep misfiring until restart, just like this car.
Having done the walnut shell blasting on my other 335xi, replacing this sensor is annoying but straight forward for me. I might clean the valves at the same time.

Just trying to figure out if the part # is 13537614317 or 13537547883.

[IN54NITY]

13 53 7 614 317, the first one you mentioned, looks correct to me.

[mrvedit]

Originally Posted by IN54NITY

13 53 7 614 317, the first one you mentioned, looks correct to me.

Yes thanks, I just noticed that ECS Tuning lists 13537614317 as the replacement for 13537547883.

Seems that people doing the walnut shell blasting of the valves should consider replacing this $90 sensor because with the intake manifold removed it is a 30 second job instead of 2 hours.