gti 8v wont tick over when warm

[mr mk2]

So last night I took a gamble on a cheap mk2 gti 8v, I got it home but by that time it was to dark to do anything so up at the crack of dawn thismorning to see whats what and I can get it to start off of a jump start but once its warmed up it will start running lumpy and cut out. Any ideas? There doesnt seem to be any air leeks and all wires ect seem to be connected.

[Organisys]

Digifant?

Check the throttle closed/idle microswitch on the throttle body.

[mr mk2]

Sorry yeh digi, it seems to hunt a fair bit

[Sgt_Lemon]

Few easy things you can unplug when it's running to see if they are working. Firstly try the blue temp sender on the coolant flange at the front of the head. It should start to run really lumpy when unplugged. You could try the idle control unit, again unplug it when the engine is running to see if it was doing anything. You could also try the throttle switch which is located just behind the throttle body, again if there is no effect when it's unplugged it may not being working.

[mr mk2]

Nice1 il give them ago tomorrow and see what happens, fingers crossed its an easy fix

[mr mk2]

Right just a quick update, ive tried unpluging various plugs as suggested and found that whatever I unplugged no differance appart from blue temp sender which made it run slightly better but not perfect ive replaced this but still the problem's there I have however found that the knock sensor is not bolted to the engine as its been smashed :-/ could this b the cause of my problem? Obviously I will replace anyway ;-)

[Mr Blue]

Knock sensor is a good start.

tighten the sensor to 20NM

[Sgt_Lemon]

20nm is nothing, be careful when fitting it. To test it when it's working get the engine running and up to temp and tap the block next to the knock sensor with a big spanner or something. There is probably a better way but this works just don't hit the sensor. The idle should change when you hit it. Has changing the blue temp helped, if the sensor is new with no change have a look at the wiring?

[mr mk2]

Changing the temp sender hasnt made a differance still runs slightly better with it unplugged, well I say unplugged but I mean un wired as the plug has been snapped off so just wired with 2 connectors :-/

[Sgt_Lemon]

Something is way off then, when I unplug my sensor it goes from smooth-ish idle to a super lumpy near stalling idle.