Hi guys. Got a 1990 TT. Okay heres the problem. Have just recently got an idle problem ( car seems to struggle ticking over). It's hovering at about 650rpm to 750rpm. Seems "lumpy" as well at tickover. Drives fine when you go but when stopping at the lights she struggles to tick over again. However I recently took the car off Optimax and went to Premium unleaded. Also changed the stock filters for replacement Cooper ones. The stock ones were black underneath. Since changing them and the fuel she's struggling to tick over. Now I hear members stating to check the PTU connectors and TPS connectors. Anything else I should look for?

Thanks guys.

Cleaning the throttle bodies is an easy and often effective starting point, followed by TPS connectors. Check here for details www.z-car.net

 

Does the tickover struggle when the a/c is on ?

 

Just turned it on. Fine until after a couple of minutes..then she struggles. Switched AC on and BINGO! She's running smooth at tick over at about 950rpm! Turn AC off and she struggles again. Tried wriggling TPS/Connectors etc..no difference..even PTU connector. I'm stumped.

Ha, don't be. You probably need to look at the connectors for the IAA or AAC valve. Details are on the site mentioned above.

did you remember to reset ECU after changing filters. leav dissconected for an hour.

I never knew you had to disconnect the battery when you changed air filters? Is this required? How do I get round this problem now?

One thing I havent done and that's try the idle air adustment screw. Guess I should try this first?

Nope, that just sets the baseline idle - should be around 600rpm, the ECU takes over after that. Unless the ECU gets proper signals from all the sensors and is able to twiddle the IAA itself then tickover won't be correct. When the a/c is on the FICD (fast idle control) takes over and keeps the rpm a little higher.

 

What you need to do is clean the IAA, clean the the throttle bodies, set the TPS voltage correctly and I would expect all to be well.

 

I had to do this to mine about 2 weeks ago - has been 100% ever since.

 

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Same problem has been bugging me for months. I worked my through all the obvious cures... cleaning throttle bodies, removing and cleaning the Intake Idle Valve, changed spark plugs, air filters, fuel filter etc.... all with no sucess. Bought myself a digital Avo today to set the Throttle position sensor, which is now done, but also checked out the coolant sensor, only to find the connectors all furry and slightly corroded. Cleaned them up, turned the key and WOW!!!! As Mark Evans would say "Top Job" It's now working Brillo!