Been stalling but would restart. Now won’t start at all

[Dave webster]

BiU

[Dave webster]

23 hours ago, Dave webster said:

BiU

Hi I have a q7 which started stalling whilst driving. would always restart immediately however now won’t start at all. 

[JMKC82]

Hi David,

More details of the car?  Petrol / Diesel, auto/manual, FSH, etc.  Have you had the car long?

You said stalls whilst driving, does it depend on speed or gear?  Do you mean stalls from a standstill?  More info here.  Does it cough or properly stall?

Thanks,

[JMKC82]

just to add, you said it won't start.  So it is turning over okay?

[Dave webster]

Had the 2007 Q7 3.0 diesel about 3 years. Recently started stalling while driving blamed running it low on fuel at first.  Then started doing it regularly but would always restart.  This would happen every few miles so thought I’d change the fuel filter and now won’t start at all 

[Steve Q]

I'd recommend a diagnostic check to see what fault codes flag up. It could be the fuel pump, MAF sensor (would run rough before cutting out though), cam sensor, lambda sensor. 

[Lloyd1283]

Hi did you manage to get any help with this issue.I currently have the same issue with my Q7 2008 model.

[GrimleyQ7]

I had this issue with my 2007 3.0 TDi.

Diag scans showed nothing.

Would run fine when cold but then when warm (normal middle of the gauge temp) it would just cut out for no apparent reason.

It wouldn't restart until the engine was cool again. When trying, it would turn over for a few seconds then stop.

Sometimes it refused to start even then and had to be coaxed with easy start.

I took it to a electrical and sensor specialist who tracked it down to the crank sensor.

He left it running with his diagnostic machine attached and when it cut out it threw up some weird code that he said wasn't an Audi code, hence the Audi diags didn't detect it.

Had that replaced and it's been spot on and running a lot smoother since.

One thing I did notice, when it had cut out and I tried to restart, the rev counter did not move and it wouldn't start. When cooled, the rev counter would jump a little on crank then I knew it would start and this is what led me to think crank sensor.

No crank sensor signal means no injectors firing.

Hope that helps

Chris.

Edited February 13, 2023 by GrimleyQ7