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sdw96
Regular
Date registered: Mar 2012
Location: MA, USA
Vehicle(s): ‘15 G63, ‘19 BMW X7, 98 M3, 89 Grand Wagoneer
Posts: 76
| Missfire help
On my 2015 G63 with 80,000 miles
Been noticing for a while years an occasional slight pop sound from the exhaust. Asked dealer about it and surprisingly they never had much to offer. This week noticed the "pop or hickup" becoming a little more pronounced. Plugged my computer in and there was an error code for misfire on 8. Later that day the check engine light came on as well. I erased the code and it came right back. Decided to replace the coil pack on 8. Got a new one from the dealer and it was easier than I expected to replace. Given 8 is all the way to the back on driver side. Anyway, after starting back up it sounded pretty good and was pretty happy and went for a test drive after 10 minutes and getting back to idle the hiccup was back and the code was still there. All the plugs were replaced on dealer service a few months ago so I doubt that's it and the problem was around before then anyway. Talked to a mechanic buddy who said to check O2 sensor values, so I did and they were fine. the left sensor voltage was a bit higher than the right (.719 v .196 with normal range .1 - .82) Only other things I could find were at idle the inlet manifold pressure was low 228 hPa ( normal 305 - 405 ) and under acceleration boost pressure getting a little out of range on the high side as well but no by a lot. Doubt that's related.
So any ideas where to chase next for the cause of a misfire on 8. |
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GwagenLover
Extreme Veteran
Date registered: Apr 2006
Location: Winston Salem, NC USA 27104
Vehicle(s): 2016 G550 & 2016 GLE350
Posts: 475
| Re: Missfire help
If you checked the sensors, then....
I would suspect one or two of the new plugs the dealer installed.
Even the coil pack you installed might have failed.
New does not mean flawless.
Get two and begin a system swap.
Then try again. |
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sdw96
Regular
Date registered: Mar 2012
Location: MA, USA
Vehicle(s): ‘15 G63, ‘19 BMW X7, 98 M3, 89 Grand Wagoneer
Posts: 76
| RE: Missfire help
So I went to the dealer because I didn't have the 12point spark plug socket and couldn't get one here till late in the week (travel plans before then). They got me in and out in 45 min and changed the plug for me as well. Cleared the codes and it stayed clear. Drove home and it hasn't put on the check engine light but I can still hear little misfires occasionally, think it's only a matter of time. The old plug ( low mileage on it as was replaced a few months ago) looked fine, no oil, no over build up of anything or discolor. The dealer says if this doesn't solve it next step is an expensive compression test which leave me with a few questions.
1. They say it's a 5 hour job and the have to tear down the top end to do it. Is it not possible to do it the old fashioned way I have done before with a gauge on one cylinder and crank it?
2. Why is the next logical step a compression test?
3. Nothing in the oil, no smell to the oil, no oil on plug, so would say rings are safe. No smell or issue with coolant so would say head gasket ok. So that leaves a valve issue, is that common? Also could it be an injector issue?
Thanks Team.
PS this board seems so quiet compared to how it used to. Where has everyone gone? |
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sdw96
Regular
Date registered: Mar 2012
Location: MA, USA
Vehicle(s): ‘15 G63, ‘19 BMW X7, 98 M3, 89 Grand Wagoneer
Posts: 76
| Re: Missfire help
well as it turns out after a compression test I have a valve problem on 8. Now what to do.
Seems like first thing is to find a new forum as there seems to be an echo in here now. Thanks Pointed three for all the years, enjoyed you very much but it seems this is goodbye. sad |
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Otiswesty
Administrator
Date registered: Jun 2007
Location: Portland, Oregon
Vehicle(s): 463.241, 461.213
Posts: 3018
| RE: Missfire help
I don't know much about the G63s so I'm not much help.
If you had issues with a m110, om617, m103/104, or m113 I think you would get more ideas from the community here.
The active membership here is thinner than it was a few years ago, but some very knowledgeable people still check in regularly, even if not posting.
Sorry to hear of the issues with your G63. It must be a hoot to drive when it runs as it should. |
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