M52TU Cold Start Idle Stall, VANOS Seals Already Done

[TiagE39]

'99 528 M52TU. Started up 24 hours since last drive. Ran with a healthy idle for about 5 minutes, then it "hiccuped" like these engines do when they have bad VANOS seals. It did it once, recovered, then again 3 or 4 minutes later and stalled. Was not driving it (parked and idling) at the time. Seals were done using the Beisan kit about 5k miles ago (mid August), and between then and now I have not had a single issue or complaint.

Restarted car and gave it a highway drive. No discernible issues, and no more stalls. No CEL.

It's about 25F out here in Northern NJ right now, so I'm more than willing to chalk this up to "cranky old BMW in cold weather." Other thoughts include failing MAF, failing VANOS solenoid (which never happens, right?), failing cam position sensor, or worn spark plugs. Anything worth exploring?

FYI this car currently needs some tensioner pulleys and a new alt (both are noisy but operating voltage is at 14.5V).

[effduration]

Restarted car and gave it a highway drive. No discernible issues, and no more stalls. No CEL.

It's about 25F out here in Northern NJ right now, so I'm more than willing to chalk this up to "cranky old BMW in cold weather." ... Anything worth exploring?


No - Keep driving it.. but continue to listen, smell, feel, & observe to monitor your 20yr old BMW's health.

[danb1979]

I'd be looking at cam/crank sensors, but also check the intake boot from MAF to TB back and see if there are any splits (they split in the ribbed sections and sometimes they're hard to see)

Have you had the codes read? If not, get that done as it could pinpoint whatever may be failing

[ross1]

The cam sensor could be causing something like this but my experience with failing sensors is that they act up more when hot.
Vacuum leaks usually don't manifest themselves this way and it ain't spark plugs.
I know you don't want to hear it but your symptoms really do sound like the classic VANOS issues.

[Mless5]

Fuel pump?
Though I wouldn't be surprised if running at this high of a voltage the car just starts to freak out in the electronics department.

[mattmar1]

14.2 vdc is the high limit for charging voltage...might look in to a new voltage regulator for the alternator or replacing the whole alternator.

[TiagE39]

Did some code scans with PA Soft and INPA, only DTC code is for my Aux/Condenser fan which was replaced and is in fact working. Will check the voltage again, I might be rounding with that number.

[TiagE39]

Have been doing a LOT of reading about this issue. It appears that M52TU's re-developing the cold start issue is not unheard of: https://www.bimmerfest.com/forums/showthread.php?t=835640. I happen to personally know the guy who owned the '00 528i in that thread, so I will be getting a full history of what he fixed and where he went with it.

In the meantime, it looks like a DME update would technically fix this, but that feels like a cop-out. If it's running properly the software shouldn't matter.

[ross1]

A later post in the fest thread accurately states that if the software was working before it should still work. While an "update" might make things better it seems a treatment for the symptoms and not a cure.
I'd be real interested to see what another VANOS unit would do for this.

[dmarkovina]

With INPA you can see the movement of the vanos pistons in real time - it has to be smooth not jerky. If you have. No error codes than your camshaft sensors are fine. On a side note I have resolved a myriad of cold running issues just by adding Ceratec...vanos seals done 12 years ago with Beisans kit all good. The engine(s) now run incredibly smoothly from the get go. 1 bottle enough, every oil change (10k miles).

[TiagE39]

Awakening a thread from the depths here I know but I hate leaving a story unfinished. I've had the VANOS coughs resurface again (much more strongly this time) seemingly in relation to this cold weather we've been having in the NE. Been doing a lot of research on E46 groups since most of the knowledge on the M52TU seems to reside there. There's a strong argument for the intake/exhaust cam sensors being at fault. They seem to lose their sensing resolution with age, to a point where they aren't useful for precise VANOS piston movements but still work for running the engine in general. If mine are original they've done 287k miles, so it's likely they are end-of-life.

That being said, I took someone else's suggestion and reset the DME adaptations using INPA. Since then it has started and warmed to op temp on cold days without a single RPM twitch. I've also noticed easier driving/getting into gear and a happier power/revs relationship on accel. Will keep monitoring and see what happens.

Does anyone know if disconnecting the battery is supposed to reset DME adapts, or can only INPA do that?

[balidawg]

Battery disconnect does not reset VANOS adaptations. Just use INPA for that. VANOS rarely causes cold start or idle issues.

Any DME trouble codes?
Do you have a thread for this issue on e46fanatics?
What are the fuel trims and MAF value at hot idle?

[effduration]

OP - Thanks for the follow-up. I have the same car - '99 528i - mine's a 5-speed.

Mine only exhibits these symptoms in very cold weather...close to zero degrees or below.
But I also don't idle my cars from a cold start-up, I drive them.

I would suggest you clean your idle speed control valve, your throttle body (carefully - just spray it), check your disa valve and replace its gasket, and see if that helps.

[Arawak420]

Try cleaning your maf sensor as well. It doesn't always throw codes but will cause cold start idle issues. Don't touch the sensor tho. Its very delicate. Just spray clean with maf cleaner.

Sent from my SM-N960U using Tapatalk

[Mike WW]

I vote cam sensor.

I did have a M52tu for ~140K miles. Pretty severe Vanos issues around 125K not too long after I bought it. But it was surging/sometimes stalling when cold, along with generally running crappy, but no code nor any stalls when warm. Vanos rebuild worked wonders.

Different car. M52 stalled once as the cam sensor was failing, 30 miles into a drive, fully warmed up, pulled up to a stop sign and it died. CEL went on, it started right back up. Ran lousy, doggy, but didn't stall again. Replaced the intake cam sensor and BAM, all was right with the world again. I did use a BMW sensor and overpaid for it, but it worked perfectly and has been for several years now. YMMV.

[BMW4RE]

I know this is an older thread but wanted to add my overpriced two cents. Recently I had a CEL thrown that seemed to point to the cam position sensor on the intake side. The only symptom I noticed was that it seemed to be running very rich at startup. After replacing the CPS with the expensive factory part the car doesn't seem to be running rich on startup anymore. My codes were a #15 BMW and a #1525 OBD II generic number, IIRC. I have not driven the car much since replacing the part so things could change. Fingers crossed they don't. Cheers.

[tk59194]

I've read through this thread and countless others trying to diagnose my cold start stall issue on my 99 E39 528iT. I've replaced the van is seals, cam sensor, all hoses, MAF is good. Car is fine when driving it, but if I try to warm it up, it dies after a few minutes. It's not throwing any codes. What's worse it's in a BMW shop (not the dealer) and the owner called Friday to tell me they cannot find the problem. Software showing everything is normal. They did a smoke test and found no leaks, fuel system is fine, etc. It's not a big deal, but annoying to say the least. I haven't cleaned the ICV yet nor have I replaced the intake temp sensor located on the engine cover/valve cover. Not interested in reprogramming the DME as my car is Dinan tuned and has been since 01 with no issues. I'm all ears if anyone has suggestions of anything else to try.

[TiagE39]

Just wanted to come back and give another update. No cold start or RPM twitches since the DME adaptation reset. We've had some truly cold days here in the northeast but it's been behaving extremely well.

[tk59194]

Going to look into this. Do you know if I'm able to do this with an active Dinan tune installed? Also, I don't own INPA. Where can I get these adaptations set on my DME? Is there another way to reset beyond INPA?

[blarf]

The pistons themselves can stick. You need a pretty deep 32mm socket (83-30-0-493-363) to take everything apart but it should otherwise be an easy repair. The part's been updated and the current number is 11-36-7-560-298.