Car running rough--misfire fault codes

[cngizbleevng]

On my way home from work I decided to keep the rpms in the 5500 range for a few minutes to blow the cobwebs out of the engine. Typically, I keep the rpms below 3500 at all times.

Unfortunately, right afterward this resulted in the engine running rough (felt a rhythmic pulsing as I was driving further). The pulsing changed its rate with engine rpm but not speed.

Got the following fault codes via Torque...

Pending Fault Log
------------------
P1343: [BMW] Misfire Cylinder 1 With Fuel Cut-off


P1345: [BMW] Misfire Cylinder 2 With Fuel Cut-off


P1347: [BMW] Misfire Cylinder 3 With Fuel Cut-off


What did I do to my car?

[z3forlife]

You could swap coils and see if the faults follow the coils or not.

[MIKYZZ4]

Clear codes, go to work and back, see what codes return.
Based on what occurred, when were sparkplugs last changed?
Since you attempted to remove cobwebs...lol, try this:
https://www.youtube.com/watch?v=_Vo4fm0JDPY

[Mr Bingley]

Is there any smoke coming out of the tail pipe associated with this? Have you looked under the hood? Any noises?

[cngizbleevng]

Good suggestions, thanks. I'll try to do some investigating today.

Spark plugs were replaced 40k miles ago so they are overdue (didn't realize it had been that long ago). No smoke or smells were noticed. No noises other than the engine running unevenly.

[cngizbleevng]

Ok, so this is weird. I started up the car this morning and it's running fine. Cleared the codes. We'll see what happens next.

[BimmerBreaker]

Since it only affected one bank I would think maybe something like O2 sensors

Im not sure holding 5500 rpm is the best thing to do, maybe try a few blasts to redline next time

[cngizbleevng]

Is a few blasts all it takes to burn up some of the carbon build-up?

The redline indicator on my dash starts at 6200 RPMs. I figured I was safe at 5500.

[MIKYZZ4]

Was it being driven at 5500rpm?,
or was it held at 5500rpm in neutral?

[cngizbleevng]

Driven. I know it's not good to rev in neutral, but I thought I was okay driving it for several minutes 10% below redline.

[rf900rkw]

If there is carbon buildup, there is something fundamentally wrong. ULEV engines do not have incomplete combustion. If there was something that made you think it needed blowing out, it wasn't running correctly to begin with.


I see nothing wrong with a few minutes at 5500, moving or neutral.

[MIKYZZ4]

Inspect plug conditions, they can reveal clues.

[cngizbleevng]

If there is carbon buildup, there is something fundamentally wrong. ULEV engines do not have incomplete combustion. If there was something that made you think it needed blowing out, it wasn't running correctly to begin with.


I see nothing wrong with a few minutes at 5500, moving or neutral.

Thanks for chiming in, Randy. I suppose owning a direct injection Mini for several years has got me paranoid about carbon buildup. I don't want to ever do the walnut blasting again.

- - - Updated - - -

MIKYZZ4, yes, new plugs are on the list. Any consensus as to which plugs are best for the M54?

[MIKYZZ4]

BMW BKR6EQUP Spark Plug - NGK 3199

https://www.fcpeuro.com/products/aud...g-ngk-bkr6equp

[cngizbleevng]

I'm about to replace the spark plugs, but I noticed something interesting on my drive to and from work today (25 minutes each way).

The engine starts up fine and runs well, but about 15 minutes into the drive, the check engine light comes back on and the cylinder misses occur again. If I pull off the road and shut down the engine and then restart it, it runs well again. Did that a few times and it runs well upon restarting the engine.

Also, the cylinder misses seem to recur when I shift and don't quite match revs. Any jerky shift tends to make them come back again.

New plugs are going in later today. I'll also change coil positions.

[cngizbleevng]

The new codes. Pretty similar to the other day except for the first one.

P0172: System too Rich (Bank 1)
P0300: Random/Multiple Cylinder Misfire Detected
P1345: [BMW] Misfire Cylinder 2 With Fuel Cut-off
P1347: [BMW] Misfire Cylinder 3 With Fuel Cut-off

[rf900rkw]

A cylinder will miss, but you deon't really notice it. The computer does, however, and after a bit shuts the cylinder off. This is when you really notice it, and is cleared by cycling the key. This is what the "with fuel cut-off" means. The computer is telling you it totally killed the cylinder due to a misfire.

[cngizbleevng]

Yes, I figured that was probably the case--seemed more electronic in nature than mechanical.

Anyway, I've got the plugs replaced and coils 1,2,3 moved back to the 4,5,6 position. I'll give the car a run tomorrow.

BTW, plugs two and three had a small amount of oil (about a drop) that had seeped above the collar. They were as tight as the other plugs when they were removed though.

[rf900rkw]

Just shooting from the hip... it sounds like you have a B1 O2 sensor that has gone rogue and is reporting too rich. Way too rich. The computer backs down the mixture trying to get in line, and the overly lean result causes the misfires on bank 1.

[cngizbleevng]

Well, I'm no stranger to replacing 02 sensors.

Why is it that Z3s go through O2 sensors so much? Does the fact that the car burns some oil tend to foul the sensors?

[rf900rkw]

I have yet to have an O2 sensor fail in any of my cars. Two of them pushing 300K miles.

[cngizbleevng]

Took the car for a run. I could tell the car was running rough at times, though the check engine light didn't come on. There were pending fault codes though...


P0172: System too Rich (Bank 1)

P1343: [BMW] Misfire Cylinder 1 With Fuel Cut-off

P1345: [BMW] Misfire Cylinder 2 With Fuel Cut-off


So, spark plugs weren't the problem, and neither were the coils (since they were swapped but the faults still came back to cylinders 1 and 2.

I guess the next thing to replace is the O2 sensor.

Am I correct in thinking it would be the upstream sensor toward the front of the car?

[rf900rkw]

That is a primary suspect. Does your scanner do live data? If so, check the LTFT and STFT for bank 1. Should be nearly 0, but ethanol will typically put the numbers in the 3-5% range. That code says the STFT is crossing -20% at times.

[dreamrider01]

Have you done a COP swap to see if codes follow the swap? Similar thing happened to me a couple of weeks ago, but just 1 COP had gone bad in my case. Same symptoms, though.

[cngizbleevng]

That is a primary suspect. Does your scanner do live data? If so, check the LTFT and STFT for bank 1. Should be nearly 0, but ethanol will typically put the numbers in the 3-5% range. That code says the STFT is crossing -20% at times.

I'm using the Torque app on my android phone. it uses bluetooth to communicate with an OBD scanner. I'm not sure of all its capabilities, and I don't know what LTFT and STFT stand for anyway.

Have you done a COP swap to see if codes follow the swap? Similar thing happened to me a couple of weeks ago, but just 1 COP had gone bad in my case. Same symptoms, though.

Don't know what COP stands for.