A4 TDI Starting issues when hot

[Ronnyuk]

Hi Guys,

 

New to this forum so please go easy on me :)

I have read through posts with similar issues to what I am having and wondered if anyone can throw some light on it please?

I have a A4 S - line Convertible 2007 2.0TDI which will not start when the car is hot, I will explain what I have done so far!!

So in the morning the car starts fine, it drives perfect all the time and I get a good 50-60mpg no issues at all, about a month ago I parked up and went to move the car after an hour but it wouldn't start, engine turns over fine but no fire, so I had it towed home and in the morning I tried it again with a nearly flat battery and it started.

Forward on a month and its now getting worse, I have read tons about this so changed the coolant sensor and fitted a new battery as the old one was a Moll from 2007 but its still doing it, if you start it and turn it off then straight back on it fires instantly but randomly it will not start if I go get fuel, shopping etc. Its been into a Audi specialist who cannot find a fault and it has been scanned many times and no codes are showing, I have no CEL either.

Now if I leave the car for approx. 2 hours it will start, sometimes a bit longer than normal to start but it will go. I have seen issues with the starter motor but the garage says its not that as it turns over fine around 400 rpm iirc, they checked the Crank and Cam sensors and they work ok but I have seen on the net that A4's have a issue where the starter motor has some sort of heat sink issue, the Audi place wants it to go to a Derv Fuel specialist to check injectors etc. but I am reluctant as the car is perfect apart from the starting issue and they think its fuel related, they checked the fuel pump too and that purrs away nicely when you turn on the ignition.

I have tried starting the car with the coolant sensor disconnected and it still will not start when warm. Any ideas?

Sorry for the novel of a post haha

 

 

[Magnet]

Hello ?,

Having read your post, I think your Audi chaps are offering sound advice by suggesting you use a diesel specialist to further the investigations. My first stab at this would be to get a leak-back test done on the injectors to test their efficiency, and I would expect a diesel specialist would go down that line and others to solve your problem. 

If you enter your location then it's possible that someone on here may be able to recommend someone in your area. 

Kind regards,

Gareth.

[niedzial1983]

Found this online from a guy who had same issues . Looking at the cost ita worth checking 

"Finally fixed !
Intermittent fuel pump relay,located under ecu £16 from VAG."

[niedzial1983]

Also one more that i found 

"Bang on mate, a new battery fixed my hot starting issue. It's been probably 6 months since I changed it and the problem has dissapeared."

[Ronnyuk]

Thanks for the replies guys,

 

I fitted a brand new battery so that rules that out I also upped the CCA to 700 just to give it that bit extra.

The 2 hours thing has stumped me though, at first I was turning the car over like crazy and there Is no way it would start till the battery went flat, then I wait for a jump from someone and it starts, so I tested the theory and yup every time I wait 2 hours without madly cranking it in between it starts perfect. The fuel pump is still wurring even when the car wont start so doesn't that rule out the relay? 

I am going to do a bump test on it tonight and this should prove starter motor as if it was a fuel issue it still would not bump or am I barking up the wrong tree?

Any help appreciated, at least I know I can only use the car for journeys that I have 2 hours at the end or I leave it running  :)

Its booked in Thursday to a diesel specialist but if its the starter I can get that done buy a local mechanic.