Non-starter

[beastman]

Hi

problem with car wouldn't start today after a 15 mile run stopped for 10 mins jumped in expecting usual first turn of key but was just turning over not firing up. Could smell the petrol after churning it away a few times left it couple minutes then JUST started. Got home running as normal stopped tried to start again and wouldn't. Ran vagcom and no faults. Now has been sitting for little while starting first time!

Are there any sensors parts of ignition system etc that can cause this or any other thoughts? Run car on Shell Vmax or Tesco 99, plugs were changed 13k miles ago and checked at service 3k ago and didn't need replacing.

Neil

[neckarsulm]

Sounds like a coolant temp sensor that could be going open circuit within a certain temperature range.
You need to use VAG COM measuring blocks to read the temp sensor signal at the time when it wont start.
If it thinks it's -43 degrees when it's really 15 degrees ambient it'll overfuel and not start until it's cooled down a bit and the temp sensor is reading correctly again.
Had this on a A4 1.8 20v, different car, same sensor, same age car too.
Could be something else but seeing as you have VAG COM, worth a try..

[beastman]

Sounds like a coolant temp sensor that could be going open circuit within a certain temperature range.
You need to use VAG COM measuring blocks to read the temp sensor signal at the time when it wont start.
If it thinks it's -43 degrees when it's really 15 degrees ambient it'll overfuel and not start until it's cooled down a bit and the temp sensor is reading correctly again.
Had this on a A4 1.8 20v, different car, same sensor, same age car too.
Could be something else but seeing as you have VAG COM, worth a try..

Thanks you should be a mechanic phoned Jon at Vagtech as quite close and he thought same and just back with new sensor fitted and, touch wood, starting back to normal.

[neckarsulm]

you should be a mechanic

...well I did write a 2 page feature on VAG COM for Audi Driver magazine in around 2003 and used this exact fault as an example of how useful it was