Friend with a 5xx BMW problem

[SvenG]

Honest, I am asking for a friend

He has a 5xx BMW sedan that gives no computer diagnostic errors but has an intermittent problem.

He used to be in auto service and repairs so he is not car ignorant and the service manager at the local BMW dealer is from the same town so they get along famously. IOW, I do not think the BMW service guy is pulling a fast one when he says he can't figure it out.

The problem is that when the car is driven for 60-100 miles and then comes into city traffic it will sometimes stall in the stop-n-go traffic. Usually it will start back up but the last time he had to wait for a few minutes before it would start again. In normal city or shorter freeway driving it never has a problem, it only acts up after a longish drive.

Any ideas ?



-Sven

 

[hard top]

Any ideas ?

It was the cooling system that caused my 3 series to do that.

 

[SvenG]

Hi Mike,

It was the cooling system that caused my 3 series to do that.

Interesting, did it overheat or was it some other cooling system malfunction ? I assume he'd notice the temp gauge overshooting and he didn't mention anything like that.

Thanks,



-Sven

 

[Ianmc]

That was a symptom of the camshaft sensor failing on my Z3. Know nothing about 5 series though.

 

[pgunter]

Sounds like fuel starvation when the engine is hot. Is this a petrol or diesel engine ? As @Ianmc states, it could be the cam sensor, but that should throw a code. It sounds like a game of hit and miss. If its a petrol, sounds crazy but disconnect the MAF sensor and see if that still cuts out. Hot engine bay and air hose could be that simple.

 

[hard top]

I assume he'd notice the temp gauge overshooting

Mine did not move to start with during driving but did later on running stationary.

 

[Tfp]

If no codes it sounds like an air leak.

Main dealers rely too much on diagnostics nowadays.

But as said above, symptoms of a cam sensor gone, has the car been fitted with an aftermarket cam sensor?

 

[5harp3y]

CAM sensor
Idle control
fuel starvation / boiling

without diagnostics might need a lot of trial and error