I was wondering if any body could help me. I have a 97 (pre facelift) 1.3 MPI Felicia and am having problems with the tickover speed during idle when the engine is warm.

The car used to have throttle response issues so after reading the forums I decided to clean the carburetor as recommended in many of the other posts. I disconnected the throttle cable, opened the butterfly valve and cleaned the insides using a cloth. I didn’t fancy the carb cleaner approach like others have used. Put every back together and the car now runs really smoothly none of the low rev judder that used to mean that the engine was about to stall.

However I have notice that something has changed.

The car starts all as normal, usual tickover speed, but once the engine gets warm, the tickover speed seems to have increase by a few hundred revs. (Cant tell exactly how much as I’ve got the clock dash and not the rev counter). The engine runs completely smoothly, doesn’t hunt, but just goes that little bit faster.

My concern is that the tickover might be too fast resulting in an MOT failure, it also seems to be losing about 6 mpg during my normal driving. I’ve adjusted the throttle cable, which made no difference. I have also watched the car run with the air pipe disconnected from the carb and it doesn’t look like the throttle is opening itself any further to increase idle speed.

Last weekend I checked the breather pipes that go into the base of the throttle, cleaned all the electrical connections, both temp and map sensors appear to functioning normally. By randomly unplugging various leads and reconnecting I have been able to make the car run perfectly on two occasion, but by the time the engine is restarting from cold the problem returns.

If anyone has any comments or advice it would be greatly appreciated.

This sounds like a problem with the cold enrichment not shutting off. The usual suspect is the engine temperature sensor.

Would that be the temp sensor as part of the thermostat assembly or the one in the air filter box?

The temperature sensor in the thermostat assembly seems to work okay, judging by the gauge in the dashboard. However when I unplug it all that happens is that the gauge drops back to zero (in the dash) with no noticeable effect on the engine tickover. From what I have read on another thread this should cause the car to start to run lumpy etc and that there should be an obvious effect on the engine.

since you disconected the cable probably you put it on and is a little tight, the cable should be a little lose when the gas pedal is not being pressed

what about re-calibrating TPS ?

i am not sure on that but all experienced members of skodaclubs in Turkey talks about re-calibrating throttle position with vag-com after cleaning.

Edited 4 October, 200817 yr by AhmetH

I just cleaned the throttle valve (butterfly, as you call it) with some cloth and a bit of redex.

I couldn't reach some areas, so I decided to unmount the block.

I cleaned it, especially the edge of the butterfly.

After remounting the all thing, I started the car to check.

The idle speed was around 1500RPM...

After few minutes, it dropped to 1100RPM, to finally drop back to 750-800RPM, as it was before.

I took the car for a drive test, and noticed smoothness and better response from the engine, but no more bunny hops (or kangaroo jumps, pick the one you like! :P).

The idle revs stays now around 750-800RPM.

In my opinions, it sounds like the ECU needs to recalibrate itself, and it can take few minutes to do so. Till then, everything is fine.

no matter what i do, cold idle is 2000-2300rpm, and then it drops direcly to what i set it to wich its 800-850rpm, wish my ran like yours DooDle

Thanks for all your comments

Just a quick update. Having purchased a Haynes manual I tried various things to sort this problem out cleaning hoses etc, checking for air leaks but all to no avail.

I purchased an OBD cable to check everything, and the car doesn’t appear to be throwing up any errors. I realigned the throttle body using the VAGCOM software and this marginally improved the situation. Having used the diagnostic monitoring (don’t have a rev counter) it now seems to start and tick over between 1050-1200 rpm. But regardless of how hot the engine gets it doesn’t settle back to sub 1000 rpm.

As Ken recommended I also purchased a temp sender, which I installed this weekend. But on first use it appeared that one of the variable resistors inside was faulty so I’m waiting for Jorily to get back to me regarding a replacement.

As you say DooDLe the car drives better than ever, its just the fast idle and the fact that I’ve lost 5-10 mpg. I don’t think the ECUs at fault though as I’ve now driven the car in excess of 250 miles on many occasions and would have expected it to recalibrate itself by now.

I will post when eventually fixed

Other simple prospects would be the throttle cable and stop. The cable should have some slack in it at idle, but as little as possible.

If you've played with the throttle stop to try and get the engine to run better, remove the spring clip from the throttle adjuster, set the idle speed on the stop adjuster, then set the throttle cable tension as above.

i totaly agree with the last post, the throttle cable should be the problem (is at leat the most logical explanation to a higher idle after cleaning)

and by the way, remove a vacuum hose when is on idle, if you get the engine accelerating you got the fuel mix too rich after the carburator was cleanes if it chokes and dies the the butterfly that controls the acceleration is stuck and you need to use a little more carb cleaner on it....