[DaveCN]

I am trying to sort out what is happening with my daughter's car. (I am in Kentucky, she is in California - so it isnt in front of me).

'06 325i, auto, 160k miles, n52 engine.

The problem only manifests itself when the engine is still cold after startup. The car will stall when she brings it to a stop at a traffic light or stop sign. No rough idle, starts back up immediately. After the car has been running several minutes (She says less than 10) it never happens again.

She has taken it to a reputable Indy BMW shop in Orange County, and they were able to replicate the stalling, but can not get anywhere when they scan the car - no codes at all.

I had thought maybe a small vacuum leak that heat "solves" when the offending part expands a little - but I would have expected some kind of fault codes with that.

Same thing with a MAF sensor or other sensor possibly failing.

Any ideas here? The shop (understandably) doesn't want to just start throwing parts at it. But she needs to get the car sorted out.

Thanks in advance for any ideas you may have.

[TunafishE93]

Normal.. Warm up car.

[mapleleaf1773]

Agreed, most people get in a car, throw it into drive or 1st and take off. If one lets the car warm up alittle the problem will not be a problem.

I have a co worker that has a Toyota Highlander. As soon as the ignition is on, she shifts to drive and goes. I tried to warn her of such things.

Of course she was offended and said I've done this all my life, my cars are fine, lol. We will see in the future when stuff like this happens darling, we will see....

If I were you, id tell her to take her time, slow down a little. Everything will be fine

[DaveCN]

I hear what you are saying, but in the nearly 4 years she has had the car, this never happened until recently. Something has changed for this to occur.

She is supposed to be moving back home in a month (a nearly 2200 mile trip) - and the shop knows this and is concerned about finding the issue as well in case it could be something that might later exhibit greater problems.

[PhaseP]

It is not normal, no car company would be able to sell a car that required 10 min warm up so that it wouldn't stall during driving.

Actually BMW in the user manual of these cars recommends to start the car and drive, not idle and sit. Only they say not to go hard on the engine while driving cold.

I had once owned a car that did that, was a Nissan. It turned out the oxygen sensor was faulty, and the heater section of it. It wasn't heating up quick enough due to heater. Once the exhaust was fully heated, it didn't need the additional help from the heater inside the oxygen sensor and it was fine.

That is one thing to check, but it should have thrown code.

Another thing I recommend for checking is any exhaust leak near oxygen sensors. The car is old, the connection flange from headers to the mid pipe rust away and start to leak. They are close to the 2nd oxygen sensors. There maybe leaks around upper oxygen sensors too. Exhaust leak will show itself as black soot on the area it leaks.

One other thing to check and try is to see reseating the MAF sensor connector resolves the issue temporarily and then it comes back again. Then the MAF connector needs to be cleaned very thoroughly, and ideally the connector plastic housing replaced. It is an issue with some 2006 N52's I had it, some others also, there is thread for it.

[lowrydr310]

Originally Posted by PhaseP

One other thing to check and try is to see reseating the MAF sensor connector resolves the issue temporarily and then it comes back again. Then the MAF connector needs to be cleaned very thoroughly, and ideally the connector plastic housing replaced. It is an issue with some 2006 N52's I had it, some others also, there is thread for it.

Wouldn't any MAF error not show up on cold engines when it's running in open loop?

It could be possible that there's a slight air leak on the intake tract or more likely a CCV hose. My car didn't stall but a few times the idle bounced around immediately after starting. I didn't get any codes at first, but eventually got lean codes and a SES light, and discovered a cracked CCV hose.

It could also be the eccentric shaft sensor. I'm only mentioning this because it sounds a bit similar to a problem I had. Is there any record of it ever being replaced?

The day after I bought my 330 I went to start it in the morning and it wouldn't start. It would crank and start but then the engine would shut off immediately. After a few tries it started and I drove the car a few times that day with no problems, and had no codes. That night after letting it cool off and going to drive again, I had the issues. After repeated attempts to start the car, I finally scanned and retrieved codes associated with Valvetronic motor thermal limits - but nothing related to the eccentric shaft sensor. I installed a new (used) valvetronic motor and that didn't fix the problem so a few days later after repeated attempts to start the car without success, I finally got a code associated with the eccentric shaft sensor. I installed a new eccentric shaft sensor which completely solved all of these problems and it's been fine ever since.

The only problem with this is that it's a lot of labor to replace an eccentric shaft sensor when it only *might* be the problem. It's tough to make that call without any explicit codes, but any intermittent failure might not trigger a code right away. There has to be a way to diagnose the eccentric shaft sensor (preferably when your daughter's engine is cold, since that's where the problem is) but I don't know the steps.

[PhaseP]

Wouldn't any MAF error not show up on cold engines when it's running in open loop?

In open loop the oxygen sensor input is not taken into account. MAF input is used from start always. (unless it has a mafless tune) At open loop, Oxygen sensor input is not taken into account because those sensors need to be heated up to a temperature before they work well. This would happen when the exhaust pipes reach high enough temperature. But those sensors have heating elements in them that help them heat up quicker before exhaust pipes are all heated up. In my old Nissan car, the computer was deciding the oxygen sensor should be ready to use all heated up and switching to closed loop, but sensor wasn't ready due to its heater not working. At any stop and idle engine was dying due to incorrect input from o2 sensor, if I had to stop around that duration of time computer had decided to go closed loop but oxygen sensor was not yet up to working temperature. After some time driving exhaust pipes all heated up and it wasn't stalling any more.

[nsjames]

this is the behavior that mine had when the ESS was failing.

check the ESS connector for oil. Verify it's data with INPA. I was able to find the dead spot in mine by watching the data and slowly rotating the valvetronic motor with an allen key. Inspection after replacement showed it was full of oil.

[tcphoto]

Odds are, there will be lean codes coming for unmetered air past the MAF. I think that you're right in thinking that it's a vacuum leak, it could be a vacuum hose, intake boot, O Ring or perhaps a PCV issue.

[smallseafishie]

It's probably Eccentric Shaft Sensor, Vacuum leak, or a bad MAF. If your daughter just needs to get going, I'd unplug the MAF sensor and force the car to run open loop. Fuel economy won't be great but probably won't stall anymore. At least until you get a proper diagnosis and repair.

I had this exact problem. It turned out to be a defective PCV valve and a cracked breather hose.

[tcphoto]

Rarely has replacing an MAF fixed a problem, I don't think I've ever heard of one going bad.

[gbalthrop]

Originally Posted by DaveCN

I am trying to sort out what is happening with my daughter's car. (I am in Kentucky, she is in California - so it isnt in front of me). '06 325i, auto, 160k miles, n52 engine. The problem only manifests itself when the engine is still cold after startup. The car will stall when she brings it to a stop at a traffic light or stop sign. No rough idle, starts back up immediately. After the car has been running several minutes (She says less than 10) it never happens again.
She has taken it to a reputable Indy BMW shop in Orange County, and they were able to replicate the stalling, but can not get anywhere when they scan the car - no codes at all... Any ideas here? The shop (understandably) doesn't want to just start throwing parts at it. But she needs to get the car sorted out...

Thoughts:
1) If issue ONLY occurs in first 10 minutes or less after cold start, then NOTHING suggests an issue that will get worse, or affect driving "Cross-country". Of course if a "Vacuum Hose" is cracked, THAT could get worse.
2) If NO CODES, then ONLY way anything can be diagnosed is by viewing Live Data using INPA or ISTA during first 5 minutes after cold start. Parameters to be monitored: (1) MAF rate (looking for too low rate due to Vac Leak); (2) ECTS Signal (looking for false high, resulting in lean fueling); (3) Fuel Trims.
2a) SWAG: slight vacuum leak (which would be evidenced by slightly LOW MAF Rate reading), which is "Corrected" when system goes "Closed Loop" by O2 Sensor input enriching fueling. Fuel Trims and Loop status (closed v. open) would confirm/refute that SWAG.
3) Idle speed can be adjusted to a HIGHER value using INPA, say from 660 RPM to 750, to see if that prevents stall.
4) Some clues could arise from knowing WHAT maintenance was done on vehicle prior to "Stall" first occurring: Engine Air Filter change? Breather Heater Recall performed (if applicable)? Anything related to VC or Breather hose, Oil Separator?

Just some random thoughts. I know you are "torn" between what you would do if YOU were driving the car, and what to do when it's your Daughter. I may have missed something, but I don't see anything that suggests that either the "issue" will get worse, OR that "forebodes" some failure driving cross-country. Please let us know HOW it works out.
George

[DaveCN]

Breather heater recall may have been done recently. I know she had it at the dealer for another recall. And they fixed something else. I'll find out.

[tcphoto]

The last recall I had done was the blower motor wiring harness.

[DaveCN]

Yep, the blower motor recall was why she took it in, but the deal did something else under recall.

[DaveCN]

She says the dealer only did the blower motor recall when it was in recently.

I am flying out and making the drive back with her, and will be armed with tools and with my Laptop with cable and INPA. I'll see what I can determine when I get there. In the meantime, the shop called today and suggested she pick up the car as they could not figure it out.

[gbalthrop]

Originally Posted by DaveCN

... I am flying out and making the drive back with her, and will be armed with tools and with my Laptop with cable and INPA.

"Atta-Boy" Dad! Sounds like a PLAN!
As for tools: Duct Tape & INPA (better than baling wire ;-)

Please let us know how it works out,
George

[DaveCN]

Originally Posted by PhaseP

One other thing to check and try is to see reseating the MAF sensor connector resolves the issue temporarily and then it comes back again. Then the MAF connector needs to be cleaned very thoroughly, and ideally the connector plastic housing replaced. It is an issue with some 2006 N52's I had it, some others also, there is thread for it.

I think I may have had to do something like this when she got the car 4 years ago. Sounds familiar.

Thanks all of you for your suggestions. I'll be in front of the car in two weeks time and hopefully can sort it out.

[tcphoto]

Sounds like a potentially fun father/daughter adventure. I think that we all know how difficult it can be diagnosing issues with these cars whether you have codes or not, good luck.

[DaveCN]

Update, she got a code, p316a, which may indicate coolant temp sensor issue. Calling another shop tomorrow to see if they can get it in.

[gbalthrop]

Originally Posted by DaveCN

Update, she got a code, p316a, which may indicate coolant temp sensor issue. Calling another shop tomorrow to see if they can get it in.

Bentley Definition for P316A:
P316A | 2EE6 | Engine Coolant Temperature Signal Stuck High

That explains stall after cold start. DME is NOT "Choking" engine at cold start 'cuz ECTS Signal indicates warm engine, so Cold Start Enrichment is NOT provided.

ECTS CAN be faulty, but short in ECTS Wiring or connector can ALSO cause LESS resistance in Sensor circuit with higher signal voltage received by DME.

Quick Test of ECTS:
1) Remove Connector;
2) Measure Resistance across ECTS Spades
3) At 20C, Ambient Temp & Coolant Temp, Resistance should be ~ 2500 Ohms;
4) At 90C Coolant Temp, Resistance should be ~ 250 Ohms.
5) If Resistance at Sensor Spades is in proper range, issue is in Wiring/Connector.
6) "Hidden Menu 7.00" will display ECTS Signal as received by DME, and that can be used to test Sensor & Wiring together. False High, or "Stuck High" signal can be read as Live Data, without any Scan Tool or INPA.

Hope shop charge is cheaper than plane ticket.
George

[smass]

Low transmission fluid can cause a stall coming to a stop with the ZF automatic.