1.9TDI hot starting problem

[agaafear]

Hope someone can help me. Have a 04 A3 1.9Tdi, with 80K miles. Car always starts perfectly from cold, but not when warm or hot.

If I'm on a journey and stop to refuel or take a toilet break - i.e. 10 mins or so, the car will not re-start without a lot of effort. If I pump the throttle it eventually re-starts after a 2-3 mins of coaxing.

Otherwise the car is running fine and the mpg, etc is good.

Any ideas or should I just get a diagnostic check done?

Thanks.

[tates1979]

Have you checked the glowplugs?

Failing that, it sounds like the problem my 1.9 is experiencing, starts fine (but maybe a tad too violently) in the morning, but short jump into the shop for 5 mins would lead to a 3 second turnover before it'll start - and even then it judders into life.

Are you experiencing any vibrations/rattles when idle? Does the car feel any different to recently?

[agaafear]

No. The car is running as normal and it takes me more than 3 secs to re-start - more like 3 mins. It only happens when the engine has been running for a while and is fully hot. Starting from cold is perfect, no more vibrations or rattles from idle than usual!

[agaafear]

I'm guessing it's a problem with some sensor on the engine, or something to do with the air/fuel mixture.

[tates1979]

No probs. Im gonna leave my car in in a few weeks to have it looked at - but it doesnt sound as bad as yours!

Good luck - keep me posted if you get to the root of the prob.

[agaafear]

Well i generally drive from A to B and stop, so it's not really a problem 80% of the time. If I'm on a journey and stop for 5 mins or to refuel then it plays up, but only when the engine is fully hot.

[Tigerman]

I had the same problem on 1.9tdi Golf ie:
- Starts and runs perfectly from cold
- Restarts ok if just turned off for a few moments
- But if left say 15/20mins from hot can't restart

Not a proper fix, but you can get around this by unplugging the connector to the engine temperature sensor (rear side of cylinder block on the right).

You can now start and then plug the connector back in.

My local vdub dealer couldn't fix it properly so offered a car swap or cash back.

[AwesomeSarah]

Hi
I would say the coolant temp sensor
Very common fault
The engine will be warm , but then it will be thinking it is cold , and then can over fuel
059 919 501A is the part number for the superceeded one , now green instead of black
Get a seal to go with it
Approx £23 ish + VAT for them
Approx 15 mins to replace
Just do it when the engine is cold too
Sarah

[agaafear]

Thanks for this information Sarah - makes perfect sense!

Where in the engine bay is this sensor located?

[rka3]

It looks like there are at least two different types of hot start issues:

1. From hot the car does not start and takes while to restart if at all.
2. From hot the car restarts every time but after some brief violent thud/judders.

I have been suffering from point 2 above (explained below) on an A3 (2007) 1.9 tdi.

1. Cold start no problems all sounds fine, idle fine.
2. Hot start horrible violent judder/thuds for 1-2 seconds then engine starts - feels like the engine is about fall out of the engine bay but it has never failed to start from hot and idle seems fine afterwards.

I have been trying to narrow down the time gap when the problem is at its worst. Once the engine has started to cool down anywhere between 90-70 on the temp gauge the restart is likely to be poor but when engine temp cools to below 70-50 on the gauge the start gets back to normal, having said that I have had the car start poorly in lower temp range.

Other points worth noting:

The Clutch, flywheel and pressure plate were all recently replaced.

Explaned problem to Audi dealer, they got the car in for diagnostics, however they tell me no error codes and they could not replicate the problem

any update on your problem or advice appreciated.