HELP: N52 Engine Stall and Weird RPM Bounce

[ShinZ4]

Hi all,

I'm posting here to see if anyone had a similar experience and to see how they resolved the issue.

I got an 08 E85 Z4 3.0i N52 Auto with 83,XXX miles and no mods.

The issue initially started the day I picked up the car. While coasting down hill in a parking lot trying to do a U turn, the car suddenly shut off. Afterwards, the car kept on attempting to shut off when I come to a stop sign but drives really smooth otherwise. This was avoided by revving the engine a little to raise the RPM. Soon the SES light came on so I took it to the dealership, where the MAF sensor was replaced with a new one.

Few weeks later, I noticed the RPM needle slightly dipping below the normal 600 RPM range with the SES light returning. The diagnosis was issues in Bank 1 and 2. This time, I've went ahead and replaced all 6 spark plugs and coil packs per specification. However, the RPM dip and slight shudder issue kept returning.

Thinking this is related to a vacuum leak, I took the Z4 to my indy BMW mechanic and completed a smoke test, which did NOT reveal any leaks and performed some preventative maintenance: gasket cover seal replaced, and electric water pump and thermostat replaced. He even went as far as to get me a new MAF sensor to see if the dealership gave me a faulty MAF sensor as the diagnostics revealed that the codes thrown were due to MAF and Bank 1 and 2 running rich.

With the new MAF sensor in place, I've been driving about 100 miles. Yesterday evening, when I started the car, the RPM needle started to bounce up and down between 600 RPM and 1200 RPM and then leveled out at 600 RPM: Assuming the engine is trying to compensate and adjust for faulty air/fuel ratio. However, it drove fine for another 20 miles allowing me to get back home without the weird RPM bounce.

This morning, when I started the car, the RPM was fine. Then I tried to drive to work and car was running fine until I came to a red light. When I was idling at the stop light, the engine suddenly shut off very smoothly as if I turned the ignition off. I put the gear back into Park and started the car without any issues. Drove a little again to the second set of red lights, and when the car was idling it shut off again. Again restarted the car and drove back home, thinking I cannot drive to work in this LA traffic with the car stalling like this. While I was driving back home, I had couple of slight stops, but the car did not shut off (While waiting for the garage gate to open and right before parking). Also when I was backing into my parking spot, I did feel the RPM being a little rough in reverse gear.

Any ideas as to what may be causing this???

Definitely not a vacuum leak..but would it be logical to suspect CVV issue or is there anyone else who had the same experience?

Most recent issues:
1. SES Fault Code: MAF Sensor, Bank 1 and 2 running rich
2. Occasional slight RPM drop to 500 RPM then back at 600 RPM (once/day)
3. RPM bounce between 600 RPM - 1200 RPM (only once, then never agian)
4. Car running smooth, but then stalling while at idle (today)

Cleared out following causes:
Vacuum leak
MAF Sensor
Spark plugs/coil packs

**I do have a new battery (Interstate AGM)

Please helppp I'm getting very frustrated with the Z4


EDIT: I found this post and thought may be a DME update might help? Any thoughts?
I checked with the dealership and they told me I still have the original DME software.

http://www.bimmerforums.com/forum/sh...-at-idle/page2


FINAL UPDATE:: The issue was cause by 2 small leaks on the intake pipe leading into the thottle body and a malfunctioning throttle body, which completely closed during idle. Throttle body was replaced and all is good.

[chickdr]

That is a tricky one. You have done the usual MAF replacement. I would go back to the original dealer who did the MAF/sparkplug/coilpack work and tell them to solve the issue. They should be coming up with a solution since they have done the work to supposedly fix it.

[Steeler]

Sounds like its choking itself out.

Idle control valve?

[JFleming]

Are there any codes (now). I have had codes with no check engine light.

Also the symptoms you describe sound similar to what mine did when the eccentric shaft sensor went bad. Check it for oil leaking at the seal where it comes through the valve cover. The oil can then seep into the sensor causing a failure. It can of course fail without the oil leak too.

Good luck, keep us posted.

[ShinZ4]

I can't remember whether the SES light was on or not. But I'm taking it into my local mechanic once I get out of work. I'll have the code read then and let you guys know.

**Would the Eccentric Shaft Sensor run the engine rich? Also I don't think E85 Z4 with N52 has ICV from my research just now. It's handled by valvtronic.

[3002 tii]

Eccentric shaft sensor needs to be replaced, which means you need to pull the valve cover gasket. However you might be able to replace just the eccentric shaft sensor seal and valcetronic gaskets first to see if that helps (in case the sensor isn't shot yet).

Shameless plug but I have those 2 seals for sale, brand new. I did this job last week and ordered extras by addident. PM me if you're interested, I'll let me go cheap.

[Asianoak]

Originally Posted by 3002 tii

Eccentric shaft sensor needs to be replaced, which means you need to pull the valve cover gasket. However you might be able to replace just the eccentric shaft sensor seal and valcetronic gaskets first to see if that helps (in case the sensor isn't shot yet).

Shameless plug but I have those 2 seals for sale, brand new. I did this job last week and ordered extras by addident. PM me if you're interested, I'll let me go cheap.

Not to thread jack.... But... Glad to hear it went well. Car running better now?

[ShinZ4]

Thanks for the input 3002 tii. I'll let you know soon.

>Quick update<
Took my car in to my mechanic who read the codes and basically getting the same codes for MAF sensor, Bank 1 and 2 running rich.
Checked the Eccentric Shaft Sensor but it's clean. I had the valve cover gasket seal replaced last weekend and he hasn't mentioned any other seals requiring replacement.
Checked the fuel pressure yesterday as well, it's running at 72-3 range at idle and with the acceleration pedal being pressed, which is a little lower than the recommended 75, but it's still above 70..so I'm assuming that's not the issue.

My mechanic will take the car in tomorrow and perform a full diagnostics. Hopefully he can pin point the issue.

[Huz-Z]

My 3.0SI N52 will occasionally, and only on cold start, do the rpm bounce thing for a few seconds after starting. Its very infrequent and disappears quickly after several "bounces" when it does happen. It never happens on a warm engine. Its never been a problem and I've just seen it as a quirk of the car. I've never had issues of the engine shutting off as the OP describes.

[3002 tii]

Originally Posted by Asianoak

Not to thread jack.... But... Glad to hear it went well. Car running better now?

Yea car pulls noticeably stronger. That was the last major maintenance item for awhile (did waterpump, thermostat and oil filter housing gasket at 65k). I'm now at 75k... also swapped out plugs and coils during the valve cover job.

Originally Posted by ShinZ4

Thanks for the input 3002 tii. I'll let you know soon.

>Quick update<
Took my car in to my mechanic who read the codes and basically getting the same codes for MAF sensor, Bank 1 and 2 running rich.
Checked the Eccentric Shaft Sensor but it's clean. I had the valve cover gasket seal replaced last weekend and he hasn't mentioned any other seals requiring replacement.
Checked the fuel pressure yesterday as well, it's running at 72-3 range at idle and with the acceleration pedal being pressed, which is a little lower than the recommended 75, but it's still above 70..so I'm assuming that's not the issue.

My mechanic will take the car in tomorrow and perform a full diagnostics. Hopefully he can pin point the issue.

If your mechanic replaced the valve cover gasket he should've replaced the eccentric shaft sensor. It's relatively cheap insurance. When doing the valve cover job, did you or your mechanic follow instructions on how to reinitialize for the valvetronic motor?

You can also pull out your vanos solenoids and clean them out. Just be sure to have new o-rings on hand fist since the ones you take off are one time use only. Compressed air and rag should so the trick.

[Z4Bh]

Originally Posted by Huz-Z

My 3.0SI N52 will occasionally, and only on cold start, do the rpm bounce thing for a few seconds after starting. Its very infrequent and disappears quickly after several "bounces" when it does happen. It never happens on a warm engine. Its never been a problem and I've just seen it as a quirk of the car. I've never had issues of the engine shutting off as the OP describes.

happens to me sometimes

[ShinZ4]

Update:
My mechanic had it over the weekend and checked everything. He noted that the Throttle Body had a lot of carbon build up so he cleaned that out. Otherwise, everything was fine.
Currently at 60 miles post throttle body cleaning. I'll keep you guys posted.

[reto]

N52 over time, the membrane crankcase ventilation valve mounted inside the valve cover dries and breaks.

Through the torn membrane into the engine gets unaccounted mass air flow sensor.
As a result, the engine can be difficult to start, unstable work (especially at idle), smoke may be misfiring, as the engine can get the dust, which enhances the wear of parts and mechanisms.
If the whistle is heard in the area of ​​finding oil separator, then the membrane is torn.
I found this membrane separately here vanos-bmw.com/membrane-for-cover-n51-n52-n52n-bmw-11127552281

[StickMon]

Originally Posted by ShinZ4

Update:
My mechanic had it over the weekend and checked everything. He noted that the Throttle Body had a lot of carbon build up so he cleaned that out. Otherwise, everything was fine.
Currently at 60 miles post throttle body cleaning. I'll keep you guys posted.

My Wife's Suburban had the same issue.
The throttle body and plate each had a big ridge of carbon.
With fly-by-wire-throttle and no bypass valve it's important to be able to idle through the small gap when the throttle's almost closed, so the carbon build up gives it fits.
Hope that solves it for you. Worked for me.

[Westersund]

Originally Posted by reto

N52 over time, the membrane crankcase ventilation valve mounted inside the valve cover dries and breaks.

Through the torn membrane into the engine gets unaccounted mass air flow sensor.
As a result, the engine can be difficult to start, unstable work (especially at idle), smoke may be misfiring, as the engine can get the dust, which enhances the wear of parts and mechanisms.
If the whistle is heard in the area of ​​finding oil separator, then the membrane is torn.
I found this membrane separately here vanos-bmw.com/membrane-for-cover-n51-n52-n52n-bmw-11127552281

OP's engine was runing rich which wouldn't be the case if air was leaking in at the membrane, it would run lean.

[ShinZ4]

Originally Posted by 3002 tii

Yea car pulls noticeably stronger. That was the last major maintenance item for awhile (did waterpump, thermostat and oil filter housing gasket at 65k). I'm now at 75k... also swapped out plugs and coils during the valve cover job.



If your mechanic replaced the valve cover gasket he should've replaced the eccentric shaft sensor. It's relatively cheap insurance. When doing the valve cover job, did you or your mechanic follow instructions on how to reinitialize for the valvetronic motor?

You can also pull out your vanos solenoids and clean them out. Just be sure to have new o-rings on hand fist since the ones you take off are one time use only. Compressed air and rag should so the trick.

How do you reinitialize the valvetronic motor???

[ShinZ4]

::Update::
So reached 100 miles and like clock work the SES light is back on with P0172/P0175 codes. Seems to be how long it takes for the ECU to recognize the issue (Every 100 miles after resetting the code) Will take it in this Friday again for the long weekend to try and get the issue resolved.

[ShinZ4]

Originally Posted by dbarton62

Sounds like its choking itself out.

Idle control valve?

you were right. it was choking itself because the throttle body completely closed at idle

[66 6]

Originally Posted by dbarton62

Sounds like its choking itself out.

Idle control valve?

I'm with this guy. This is a classic E36 issue and guess what. The same part https://www.realoem.com/bmw/enUS/par...&q=13411733090

that is used on the E36 platform is still used on the z4m......
But they now call it another name....

Pull it off and clean it out and the hoses to and from and reinstall.

[3002 tii]

Have you pulled out your DISA to see if the flap is no longer functional?

[msf143]

I've spent thousands trying to solve the exact same problem. Would you elaborate on what the cause was? You'd be my hero. -- Mike

[CLSchulski]

Mike, did you ever get this issue figured out? I have also spent $$$$ trying to resolve the issue of the engine running too rich.