Idle Problem

[bobbyk]

Ill start with this. 2001 Rio 104000 miles. Last tune up 8 months ago about 4000 miles. Tune up was just new plugs and wires. Probably about 50000 miles on the fuel filter and the air filter is newer, probably could be changed but not plugged or anything.

Here is the problem. After about 25 miles of highway driving (60 mph) when I went to exit the freeway, the car would not pick up the throttle as if the car shut off. But then I would push a little more on the pedal and it would come to life. As I continued I had to keep the pedal pushed far enough to maintain 40 mph any less and again the car seemed to shut off. When I got to a red light and had to stop the car stalled. It started right back up no problem and seemed to idle fine. I was at work at this point so I was unable to continue to see if it would stay running...

In the last few weeks I have noticed at cold startup the engine would "surge". Idle slow then fast then back to slow and so on untill I drove it enough to get it warm then it would be fine.

Any thoughts on a cause?

I was thinking fuel filter but usually idle is fine and top sped is affected when a fuel filter goes bad.

Alt. or battery not having enough at idle to keep it running but it starts fine even in the coldest weather.

I used aftermarket wires at tune up and wasnt too happy with them but it seems odd for them to be the cause of thisand not show other poor running issues.

Tomorrow I thought (if I make it home from work) I would check for a possible vaccum leak.

Im out of ideas. Any help would be greatly appreciated.

[ron1004]

It sure sounds like a sticky ISC (Idle Speed Control) valve.

This can often be cured by removing the ISC and cleaning it with 'Carb Cleaner'.

Try a search on this forum for 'Idle' , 'ISC' and 'IAC' and you'll find a good few posts with lots of detail on this.

Also check out this site for more info.
Global Service Way

[bobbyk]

RON1004, Thanks for the advice. The car did not act up on the way home from work Friday morning however I still removed the ISC and cleaned it. I will say the car seems to be running much better. It is ideling much smmother now and seems to pick up the throttle much better now. I dont know if cleaning the ISC helped that or if its just my imagination but either way Im pleased with the results. Only time will If it helped the stalling problem but with the changes cleaning it did make Im sure the stalling problem has been corrected. Thanks again