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-   -   Recent coil/misfire problems (https://xoutpost.com/bmw-sav-forums/x5-e53-forum/109772-recent-coil-misfire-problems.html)

upallnight 02-09-2019 09:28 PM
Quote:
Originally Posted by Muleears (Post 1154504)
The STRANGEST thing just happened. Started the X to go to lunch. As usual it started with a miss, and tripped the SES. Drove it about 3 miles and parked. While parked I decided to clear the codes. Foxwell said cylinders 3,4 and 5 were at fault. I let it run while I cleared the codes and heres the weird part, the instant the codes cleared so did the miss! Normally I would chalk that up to coincidence but this is the second time in as many days it has happened. WHAT is going on? Why would/could clearing a code rectify a misfiring cylinder? :dunno:
Could be the misfire is associated with a fuel cutoff. Clearing the code clear the misfire counter so the DME isn't shutting off an injector until it reaches a certain number of misfires on the counter.

80stech 02-09-2019 09:39 PM
There is a ton of stuff that can cause your problem. I would lean towards looking for a vacuum leak to start. It would be nice if you where sure that you are reading all of the codes as there should be a clue as to what else is going on to cause the missfire. When the engine is first started it has the least amount of adaptability to compensate for problems, use that to your advantage to find the problem.

Muleears 02-10-2019 07:15 AM
Quote:
Originally Posted by upallnight (Post 1154780)
Could be the misfire is associated with a fuel cutoff. Clearing the code clear the misfire counter so the DME isn't shutting off an injector until it reaches a certain number of misfires on the counter.
I think this is exactly it, because it starts with a minor misfire but it won't trip the SES light until it has run a while or the misfire is bad enough to make running very rough.

I have a mity-vac to check vacuum, but I have no clue where to start on the X. Wouldn't a code show for a vacuum leak? I guess I'll do a full scan with the Foxwell, not just the DME and see what turns up. Thank you upallnight you have given me good advice. Thank you also EODguy and 80stech for adding to this. It's 16*F this morning (thats -9C for your smart metric folks), I'll start it shortly and see if its better/worse with the very cold weather.

Muleears 02-10-2019 08:46 AM
First thing I did was read the codes, a complete scan, before I started it. Nothing found, other than the persistant air bag and side light codes. This mornings cold start yielded the standard lumpy idle, but it did smooth out in about 30 seconds and no SES light. I then read the codes again and the typical misfire of 3+5 showed up, but that was all. Sometimes the misfire stays for several minutes or miles and I have to kill the SES light with the Foxwell. Then it starts and runs fine until the next cold start.

What vacuum leak would go away in less than a minute? It seems to always include cyl. 3. The others vary but 3 is always one of the ones with a miss. Is there a cold start solenoid or circuit that turns off a few seconds after a successful start? Could the injectors be malfunctioning? How hard are they to swap from cyl. to cyl?

Thanks in advance for any additional advice, I'm not sure where to go from here. Coils and plugs are both new.

Jeff O 02-10-2019 12:51 PM
I am having an idle misfire with my 3.0 X5. Originally my plugs were worn and changing cleared it. I would try a bottle of Techron (larger bottle) and good gas (Shell or Chevron) and see if that helps. Intake deposits or injector deposits can cause this type of problem. Vacuum leaks such as failed PCV hoses or separator or intake boot cracks along with valve cover gasket leak are all common failure points on M54 engine.

Muleears 02-10-2019 03:25 PM
Quote:
Originally Posted by Jeff O (Post 1154818)
I am having an idle misfire with my 3.0 X5. Originally my plugs were worn and changing cleared it. I would try a bottle of Techron (larger bottle) and good gas (Shell or Chevron) and see if that helps. Intake deposits or injector deposits can cause this type of problem. Vacuum leaks such as failed PCV hoses or separator or intake boot cracks along with valve cover gasket leak are all common failure points on M54 engine.
Thanks Jeff O, I generally buy good gas and only premium. The current tank (filled yesterday is Citgo), last tank had a can of Seafoam in it. I'll get a bottle of Techron and give it a try.

As for the vacuum leaks I'll do some research to find where the PCV is on this thing then do some vacuum testing. I've noticed no oil leaks around the VC. The snorkel between the fresh air scoop and the air filter intake hose has a crack but it is on the fresh (unfiltered) side of the air filter, so that shouldn't affect it.

If I run across anything else pertinent I'll post. Thanks again for the help.

Muleears 02-12-2019 01:02 PM
Could this be weather related?
 
We have had a cold snap lately (just coming out of it today), I have also noticed some mayo on the dipstick and oil fill cap. I know these are related to the cold weather problem with the EGR valve/system. Temps (when I start in the morning) have been in the teens F. I know thats not cold for some of you but my X, I am sure, doesn't have any cold weather options. I have read this situation can cause an idle misfire? Need I look into this more or am I way off the track? Hopefully it will start well tomorrow morning with the warmer weather. TIA. :thumbup::thumbup:

upallnight 02-12-2019 03:35 PM
Quote:
Originally Posted by Muleears (Post 1154456)
About two weeks ago I started getting the SES light. I had noticed that it was missing a little when started cold, I figured that was what was tripping the light. Foxwell told me it was cylinders 2+3 acting up. It always smoothed out after running a minute or so. Last week it was taking more time to run on all six, sometimes a couple miles. So I bought two coils and replaced 2+3. Put in a new battery about this time also. I should point out that the plugs were done about 6 weeks ago with iridiums. The new coils initially seemed to fix it, for a day or two anyway. Today when started to come home from work (a 40 mile trip) it was rough again and the SES came back. I drove it home but noted rough running most of the trip. When about 30 miles into the commute it smoothed out and began running smoothly on all six. When I got home Foxwell told me I had misfires on cylinders 3,4,5+6! These must have been intermittant as It wouldn't run on just two! So what I have done is swapped coils 1+3 with each other. #1 has never misfired according to the scanner, so now we'll see if the miss follows the coil or not. If the skip stays in cylinder 3 (with the known good coil) where do I go? Look at injectors? I only run premium and now it has a can of Seafoam in it. I'll report how it runs tomorrow morning with another cold start and 40 mile drive. TIA

If it starts misfiring when you first start up but go away after the engine has run for a while, I would look into a leaky injector. Just like a flooded engine, a flooded cylinder will not run correctly. It is only after the engine has run enough to clear the cylinder that the misfire is no longer present.

270_BMW 02-12-2019 04:00 PM
If it is exclusively on 4,5,6 I would check your grounds for that bank. I had an issue with 1,2,3 a couple months ago. Turned out to be a seeping Valve Cover Gasket, was getting oil everywhere and down in the wells, but also shorted out my ground.

Muleears 02-12-2019 04:21 PM
Quote:
Originally Posted by upallnight (Post 1155011)
If it starts misfiring when you first start up but go away after the engine has run for a while, I would look into a leaky injector. Just like a flooded engine, a flooded cylinder will not run correctly. It is only after the engine has run enough to clear the cylinder that the misfire is no longer present.
Would this be enough of a misfire to trip the SES light and make the DME shut that cylinder off? If it doesn't smooth out on its own and trips the SES, I have to clear the codes for the misfire(s) and it then runs smoothly.


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