A few questions about misfires.....

SlicktopTTZ · 11-11-2009, 10:58 AM

Quote:

Originally Posted by dzenno

Thanks for clarifying the sound part.

Plugs are original since I got the car (have almost 50,000kms, 31000 miles on them). I've sent my datalogs over to Shiv for him to have a look to see if its air/fuel ratio related to the map which I really suspect is the case as car runs perfect stock (procede taken out).

In terms of boost leak, misfire does seem to happen only under full boost applied in 3rd gear starting early from below 3000rpm. If I'm in any other gear or even if I WOT in 3rd but above 3500rpm it seems to be not LONG enough on full boost to induce this misfire. I looked at a procede datalog and it shows consistent boost at around 15-16 when WOT for the duration of the run and this is why I don't think its a boost leak as I think it should've been visible in the datalog, no?

Another thing to mention is just before this misfire happens, there are sometimes multiple popping sounds from the back (exhaust) and a few oscillations in power and then the codes happen with the vrrrr sound...Does this sound like air/fuel gets too rich/lean?

Most likely too rich, resulting in fuel igniting after the combution chamber, which causes those backfires you are hearing. Also, if you have catless exhaust it is much easier to notice the popping.

BMW_CarBQ · 11-11-2009, 11:00 AM

dzenno · 11-11-2009, 11:16 AM

Quote:

Originally Posted by BMW_CarBQ

OMG WTF? That's crazy...any updates from BMW?

badass335 · 11-14-2009, 04:38 AM

Quote:

Originally Posted by dzenno

Did you get your misfire issue sorted out or are you running stock now or with JB3...

I'm running JB3 and no more misfires at all and i run my car hard!

Before, i would run and i would say, out of 10 times, i would get 9 misfires with procede. With JB3, i had 1 misfire but the car was still adapting. (30 mins after installing the tune) but since then no codes at all!

Mid_West · 11-27-2009, 09:18 PM

Im running the older AA Xede and have the same problem...actually I took the tune out and its been in my closet for the past few months. When an SLK 350 kept up with me today I realized that I need my tune back but Im concerned about the misfires I get when installed.

Ive got 18k miles on the car (2008) and am running downpipes (with cats) with a Spearco IC. Sure wish I could figure this out, I hate the damn pin out routine each time I have to remove the tune.

Any idea other than what has been already mentioned here? I thought about the plugs but it seems like 18k is a bit too soon for that.

11-11-2009, 11:00 AM	#24
BMW_CarBQ New Member 0 Rep 6 Posts Drives: 335xi Join Date: Nov 2009 Location: Bellevue, WA iTrader: (0) Garage List 2007 335xi http:// ... [0.00]	My Car Had Missfire Faults but didn't get corrected in time.
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11-27-2009, 09:18 PM	#27
Mid_West Second Lieutenant 20 Rep 231 Posts Drives: 335i Join Date: Jun 2008 Location: USA iTrader: (1)	Same issue with misfires and tune...but runs fine without! Im running the older AA Xede and have the same problem...actually I took the tune out and its been in my closet for the past few months. When an SLK 350 kept up with me today I realized that I need my tune back but Im concerned about the misfires I get when installed. Ive got 18k miles on the car (2008) and am running downpipes (with cats) with a Spearco IC. Sure wish I could figure this out, I hate the damn pin out routine each time I have to remove the tune. Any idea other than what has been already mentioned here? I thought about the plugs but it seems like 18k is a bit too soon for that.
	Appreciate 0 Quote