Misfiring On All Cylinders Only After Idling for a While

[giOsaurus rEx]

So I have a weird issue. It appears that my car is misfiring only after it has been idling for 10-25 minutes. When it happens, I can feel it the car shaking and the engine having some issues when I rev to 1200 - 2000 RPMs. No warning lights pop up on the dash when this happens. I borrowed my friend's ECS/Foxwell Diagnostic Scanner yesterday and cleared all the diagnostic codes that were stored previously. I drove around normally for an hour or so last night and did not experience a misfire. I scanned the car this morning regardless and the only code that popped up was an unrelated "20 IHKA: AUC heating" code for the A/C.

So I drove around slowly and let the car idle for 5-10 minutes at a time for about 45-60 minutes this morning. The misfiring happened during this session. Again, no warning lights popped up on the dash and the misfire was typically felt between 1200 - 2000 RPMs. The diagnostic scanner read out that all cylinders were misfiring. Here are all the codes that popped up in the "1 Engine-DDE Diesel Electronics DDE3.0" Auto Scan section:

1. CD. DME: Misfiring, cyl 1 without cylinder cutout
2. CE. DME: Misfiring, cyl 2 without cylinder cutout
3. CF. DME: Misfiring, cyl 3 without cylinder cutout
4. D0. DME: Misfiring, cyl 4 without cylinder cutout
5. D1. DME: Misfiring, cyl 5 without cylinder cutout
6. D2. DME: Misfiring, cyl 6 without cylinder cutout
7. D5. DME: Misfiring, several cylinders without cylinder cutout

I find it hard to imagine that all 6 cylinders are misfiring due to one ignition coil going bad. A had a service done a few months ago which included rod bearings, valve adjustment, new fuel filter, and new spark plugs. I cleaned the MAF when I noticed this problem a few weeks ago with CRC MAF cleaner because I didn't know that it was misfiring since no SES light came on. I was going to clean the throttle bodies and idle control valve, but I don't think that's the issue anymore after the diagnostic scanner. I have 112,600 miles on the car with most of the ignition coils being original to the car. I replaced one of them 30k-40k miles ago when I had a misfire with a SES light. I never cleaned/replaced any injector. Has anyone experienced this problem? Any suggestions are greatly appreciated.

[White_335i]

Can you disconnect the maf electrical plug and drive around and see if the issue comes back? Any difference in power when driving around?

[sapote]

check fuel pressure with external gauge.

[eacmen]

Since it only happens after idling for a while it could be the transition from open loop to closed loop. On a cold start the engine isn’t really listening to most of the sensors. Once engine has reached operating temp it will rely on MAF, TPS, o2, coolant temp, etc.

I would log fuel trims when the misfire is happening. Also log the sensors above to see if they make sense. Unplugging maf is also a valid diagnostic step, ecu will fall back on alphaN.

Any tune?

Also second the suggestion to measure fuel pressure. You will have to do it at the fuel filter though.

[giOsaurus rEx]

Can you disconnect the maf electrical plug and drive around and see if the issue comes back? Any difference in power when driving around?

I'll try disconnecting the MAF later today and drive around. When the misfire happens, it only feels sluggish at sub-2k RPM. Going full throttle feels fine.

Since it only happens after idling for a while it could be the transition from open loop to closed loop. On a cold start the engine isn’t really listening to most of the sensors. Once engine has reached operating temp it will rely on MAF, TPS, o2, coolant temp, etc.

I would log fuel trims when the misfire is happening. Also log the sensors above to see if they make sense. Unplugging maf is also a valid diagnostic step, ecu will fall back on alphaN.

Any tune?

Also second the suggestion to measure fuel pressure. You will have to do it at the fuel filter though.

The two TPS sensors in the engine bay and coolant temp sensors were replaced 2 years ago. I also had to replace the fuel pump maybe 3 years ago when it stopped priming. The normal driving I do reaches operating temp and I never see these misfires. I noticed the misfiring for the first time when I took my friend's kids to play Pokemon Go. We stayed in the car driving slowly around parks and parking with the engine idling for prolonged periods of time. I never done any logging before so I need to do some research on what makes sense and if the foxwell diagnostic tool can do it. To my knowledge, the car has stock tune. I will need some help to measure the fuel pressure so I won't be able to do that any time soon unfortunately.

[eacmen]

I'll try disconnecting the MAF later today and drive around. When the misfire happens, it only feels sluggish at sub-2k RPM. Going full throttle feels fine.



The two TPS sensors in the engine bay and coolant temp sensors were replaced 2 years ago. I also had to replace the fuel pump maybe 3 years ago when it stopped priming. The normal driving I do reaches operating temp and I never see these misfires. I noticed the misfiring for the first time when I took my friend's kids to play Pokemon Go. We stayed in the car driving slowly around parks and parking with the engine idling for prolonged periods of time. I never done any logging before so I need to do some research on what makes sense and if the foxwell diagnostic tool can do it. To my knowledge, the car has stock tune. I will need some help to measure the fuel pressure so I won't be able to do that any time soon unfortunately.

The foxwell scan tool 510 (schwaben) can log data. Its pretty straight forward.

Which fuel pump did you use as replacement?

[giOsaurus rEx]

The foxwell scan tool 510 (schwaben) can log data. Its pretty straight forward.

Which fuel pump did you use as replacement?

Cool I'll look into the logging. I replaced it with a BMW OE fuel pump.

[repoman89]

You say it’s fine at full throttle — full throttle is open loop mode and also requires the largest amount of fuel. So it’s most likely a sensor issue rather than fueling, likely MAF or O2. Let it idle with MAF unplugged for a half hour is an easy diag step.

[Arith2]

Did you try glow plugs?😂
try measuring fuel pressure. It could be a soft failure of the fuel pressure regulator. The more vacuum, the less fuel. When giving it gas there is less vacuum and the car should ideally have the right amount but if it's getting stuck and not cutting enough flow, you can run rich on all cylinders at idle and low rpms. It's just a thought. That vacuum line may also have a break in it at a corner and only sometimes leaks vacuum. I've seen that on other cars.

There's the MAF, fuel pressure regulator, possibly a vacuum leak, failing idle control valve, TPS (unlikely). Check the ground wires for the coils.

[giOsaurus rEx]

So I think it's the MAF sensor. I unplugged it and drove around for about an hour. The car felt more responsive at lower RPM. I replicated the driving I did when we played Pokemon. Then I let it idle for 30 minutes. No misfiring and the throttle felt smooth like it should. I'm going to do the same test tomorrow to see if it wasn't just a fluke before ordering a $300 sensor 😮

Thanks for all the help!

[repoman89]

So I think it's the MAF sensor. I unplugged it and drove around for about an hour. The car felt more responsive at lower RPM. I replicated the driving I did when we played Pokemon. Then I let it idle for 30 minutes. No misfiring and the throttle felt smooth like it should. I'm going to do the same test tomorrow to see if it wasn't just a fluke before ordering a $300 sensor 😮

Thanks for all the help!

Here’s the OE part to install into your existing housing .. $115.

https://www.fcpeuro.com/products/bmw-mass-air-flow-sensor-m5-z4-z3-m3-m6-0280218062?ads_cmpid=352576039&ads_adid=22972407319&ads_matchtype=&ads_network=g&ads_creative=85218275839&utm_term=&ads_targetid=pla-22190487637&utm_campaign=&utm_source=adwords&utm_medium=ppc&ttv=2&gclid=Cj0KCQjw38-DBhDpARIsADJ3kjnozwGuyvP8Mb03unDzk2gYmVfjiXAy4gG8CfVaeiHyDeyl5yFL_CAaAv12EALw_wcB#reviews

[eacmen]

Curious. Does anyone know what sensors alphaN uses? Is it everything except the MAF?

I think IAT is also part of the MAF harness.

[giOsaurus rEx]

Here’s the OE part to install into your existing housing .. $115.

https://www.fcpeuro.com/products/bmw...Lw_wcB#reviews

Awesome! I ended up ordering it from your link. Thank you!

[Arith2]

Curious. Does anyone know what sensors alphaN uses? Is it everything except the MAF?

I think IAT is also part of the MAF harness.

The TPS and IAT mostly. You just rewire the IAT and put the sensor somewhere. Turner airboxs use a fitting that fits the M50 IAT.

[giOsaurus rEx]

So I replaced the MAF and all the ignition coils with Bosch OE parts, but I'm still having the misfiring issue whenever it is idling for a while. Do I need to reset adaptations? Car runs fine when I unplug the brand new MAF. I got the same codes as the original post plus a few more this time when it was misfiring:

4F DME: Signal, exhaust-gas temperature sensor
AE DME: Fuel-system diagnosis, cyl 1-3
AF DME: Fuel-system diagnosis, cyl 4-6

Still no SES light on the dash when this is occurring. Can the EGT sensor be the cause of this or a combo of EGT/O2 sensors? I'm starting to think that I should ditch the MAF indefinitely lmao.