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Posts: 34
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Car: 2013 335i e92 M Sport
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Log Check- Chasing a misfire after exhaust mod -
01-02-2018, 02:38 PM
Hi guys, can you please check these over for me and let me know how things look and if I need to change any settings?
Long story short, I recently installed an exhaust mod *cough* and experienced a multiple cylinder misfire and limp mode on the first trip out on the highway. I took a quick log and noticed that it was boosting slightly over the target, so I checked the v band clamp to make sure it wasn't blocking the wastegate actuator and replaced the boost solenoid (had that lying around planning to swap out for a few weeks). Plugs/coils only have 4k miles on them so I haven't swapped them out yet, but I've got a new set on order just in case. I wasn't able to catch the misfire on these logs, but right after the last one I had a bad hiccup in 4th gear paired with a puff of white smoke, so I decided not to try my luck any further.
This is on my 2013 E92, VRSF intercooler & **, BMS intake, and BMS BEF, running straight 93 octane.
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Tuner
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01-02-2018, 07:50 PM
Timing is poor, so that could be leading to your misfires. Boost target will likely learn down with more adaption runs. More octane may help.

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Junior Member
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01-03-2018, 07:14 AM
Quote:
Originally Posted by Steve @ BMS/Fuel-It!
Timing is poor, so that could be leading to your misfires. Boost target will likely learn down with more adaption runs. More octane may help.
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So you think it's just targeting higher boost than 93 can accommodate, and that's causing the sputter/misfire? I'll put in a bit of e85 today and re-try running some logs to see if it helped. The e85 station on my commute hadn't given me great results thus far so I'll try an alternative source.
Aside from octane level, anything else it could be? The user settings should all be default or auto-adjusted, is there anything I should try tweaking after the exhaust mod?
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01-03-2018, 08:20 AM
I’d start with the octane/e85.
Then check the usual plugs/coils...
I personally can’t see doing an exhaust mod (I’m assuming you did the PE?) causing a misfire issue
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Junior Member
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01-03-2018, 08:44 AM
Quote:
Originally Posted by Dave @ Fuel-it!
I personally can’t see doing an exhaust mod (I’m assuming you did the PE?) causing a misfire issue
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I installed a vrsf ******* ********, I was just being cute about it.
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Junior Member
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01-03-2018, 04:09 PM
Was able to put in 3 gallons of E85 from a different station this morning and get a new log. I'm not sure how the data looks, but it sure felt a lot better.
Also, new plugs came in this afternoon, so I swapped those out and was able to get a quick crappy log, mainly just to make sure I hooked everything back up right. Traffic/weather prevented me from getting a proper log, but again, it felt a lot better.
Aside from feeling better, how does this new log look compared to the original? Maybe I just need to swap up to this other station from now on.
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Junior Member
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01-04-2018, 08:16 AM
Here's one more data point, for science. These were the plugs that I pulled out, after about 4k miles. They were a little bit dirtier than I would have expected, anything alarming/interesting here? They're in order with cylinder 1 on the left, 6 on the right.
Thanks!
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Tuner
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01-04-2018, 11:27 AM
Nothing stands out, whats the gap?
Logs look pretty normal, just a bit of a boost spike at tip in. You can do a little duty bias tuning to eliminate that but not a big deal.

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Junior Member
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01-04-2018, 12:01 PM
Quote:
Originally Posted by Steve @ BMS/Fuel-It!
Nothing stands out, whats the gap?
Logs look pretty normal, just a bit of a boost spike at tip in. You can do a little duty bias tuning to eliminate that but not a big deal.
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Gaps were originally set at .022.
I think between the higher octane and new plugs it's running smoothly at the moment, so maybe I'll stop being so paranoid and trying to break it all the time. 
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01-05-2018, 07:05 PM

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