Won't start when hot - classic Audi!

randall977 · 27-01-08, 06:09 PM

This is a classic Audi problem. My 200 5E starts fine apart from for half an hour after its warmed up. It refuses to start and then suddenly when the temp drops to a certain level is fine again. My two suspects are the warm up regulator and the auxillary air valve - both have bi-metallic strips. I also have a slight problem where the revs go up instead of down when the engine warms up - I suspect the two things are related. What should I replace first - the fuel enrichment device or the air enrichment device? or could it be something else... (btw it's not the CSV).

crisarc · 27-01-08, 06:24 PM

I had the same prob on my 200q, eventually changed the injectors[last] symptoms improved , they are as i am sure you know notorius for poor hot start

, you could also check the injector fan switch,,this blows cold air on to the injectors, lastly and most expensive ,weak fuel pump , relatively easy to check[in line guage should do it] although the pumps i had probs with were all fairly noisey as they got more tired, best of luck, liked
the resto pics
chris

randall977 · 27-01-08, 07:21 PM

Thanks for the advice. The injectors are new and so is the pump -a weak pump is a possibility as the pump was not genuine??? The air valve is okay I think and I can't see that the warm up regulator would stop it starting all together. What about the thermotime switch??? Thanks, I know this is a boring subject!

randall977 · 28-01-08, 09:48 PM

I have found the problem - the thermotime switch is only delivering 4.5V. Anyone know if I can get a replacement from Audi? Would this cause a problem with warm starting?

27-01-08, 06:24 PM	#2
crisarc Senior Member Classic Audi Club Member Join Date: Jul 2007 Location: shrewsbury Posts: 1,172	hot start, I had the same prob on my 200q, eventually changed the injectors[last] symptoms improved , they are as i am sure you know notorius for poor hot start , you could also check the injector fan switch,,this blows cold air on to the injectors, lastly and most expensive ,weak fuel pump , relatively easy to check[in line guage should do it] although the pumps i had probs with were all fairly noisey as they got more tired, best of luck, liked the resto pics chris

28-01-08, 09:48 PM	#4
randall977 Mr Typ 43! Classic Audi Club Member Join Date: Sep 2007 Location: Oxfordshire Posts: 838	Thermotime switch I have found the problem - the thermotime switch is only delivering 4.5V. Anyone know if I can get a replacement from Audi? Would this cause a problem with warm starting?

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27-01-08, 07:21 PM	#3
randall977 Mr Typ 43! Classic Audi Club Member Join Date: Sep 2007 Location: Oxfordshire Posts: 838	Thanks for the advice. The injectors are new and so is the pump -a weak pump is a possibility as the pump was not genuine??? The air valve is okay I think and I can't see that the warm up regulator would stop it starting all together. What about the thermotime switch??? Thanks, I know this is a boring subject!