Citroen XM Forum

.................that im going to make out of this Audi coupe
Im having real trouble getting the running issue's sorted out and its the last job out of a very, very long line of jobs already done, dont you just love a reliable german motor .
From a cold start the engine will fire ,feels like its going to start then it doesnt and wont fire at all until its been cranked for about 10 seconds it will then start and sound like its running on 3 for a few seconds but you have to keep the throttle deppressed, if i release the throttle the revs drop and it will verge on stalling then hunt for a few times leaping from 600rpm to 1100rpm before dying.
The strange thing is no matter how long the revs are artificially maintained via the throttle for it will die in this manner when the throttle is released, even when warm, but after its stalled you can turn the key with no throttle applied in the usual way and it fires into life and idles at 900rpm as it should.
Another symptom is that when hot and its been idling a while the revs gradualy tail off (after 10 minutes or so). opening the bonnet and pushing the throttle cam hard shut will make the engine rev back up and settle at a normal idle speed again. Ive found that the TPS only senses fully open or fully closed throttle and activates a microswitch at both position, but the throttle will not close far enough under its own spring to activate it all the time. There is a screw to set the throttle idle position but the butterfly valve fully closes in the intake and so the throttle will not close anymore than it already is.

I know its a long winded one but im tearing my hair out here so any suggestions would be much appreciated.
The engine is a 2.0 four cyl sohc 16v with EFI and mechanical ignition.

D

Sounds like wear in the throttle spindle is stopping the TPS being made in the idle position or you have an air leak. Just 'adjust' the TPS and see how it runs then.

It's any Audi. Barbeque the b*****d
Bob

Thanks D'man but there is no adjustment on the tps to take up any wear, there is no unmetered air getting in anywhere.........im really stumped, there is another throttle body on ebay for £30 though and im tempted to get it if not for these reasons then because i need a new throttle cable guide and audi want you to spend £750 on a new throttle body to get it
And yes it should burn.but its not mine so ive put the matches back.........for now

D

Are you sure there is no air leak as VAG throttle bodies have a habit of leaking air where they mate to the manifold due to using rubber gaskets instead of paper ones.

If necessary file the screw slots for the TPS to give some adjustment. If you manually make the switch does it then run Ok?

yes it idles fine from hot if i manualy activate the tps but still doesnt cure the cold start problem at all, i will have another look for an air leak later though, just to be sure.

Thanks
D