78F350

1994 Del Sol S Idle surges from 800-1400 after warm up when the AC is off. Cold engine or AC engaged, no problem.

I have cleaned, then swapped the FITV and IAC.
Went through 2 cans of carb cleaner looking for a leak.

I finally found that when I pinched off the line for the PCV Valve the surge stopped and Idle settled around 800 - 900. I replaced the PCV Valve and vacuum line. Still have the surge. I'm out of ideas.

Any suggestions?

Former User

Is this^ still true?

78F350

Almost... Now when I pinch off the vacuum line the surge gets slower and less extreme (1050-1200 over 4 sec opposed to 800-1400 over 2 seconds before I pinch it off). When I release the hose idle is steady at 1100 now. I can rev it and make the surge come back.

Maybe another slight leak somewhere?

78F350

Here's some video of it:
http://youtu.be/8jaxEHmml18

(The valve noise sounds pretty loud when I go to the engine, but the mic is right on the valve cover.)

Former User

Remove the air intake and let the warm engine idle until the surging starts. Then use your finger to the cover the hole/port inside the throttle body leading to the IACV and FITV. Does covering one or both holes eliminate the high/surging idle problem?

78F350

Fixed.

I took off the air intake and covered the holes. FITV had a slight vacuum, no fix. IAC choked it out almost. Maybe little air was getting by the throttle valve. That and the slightly high idle got me thinking....

Being a 'hammer and duct tape' kind of guy I took a hammer and did a light tap on the flat part of the throttle control just above the stop. The second tap dropped the idle to 800 and fortunately nothing broke*. 100+ degree weather and a week of troubleshooting I was about ready to take a sledge hammer to the whole intake.

The Idle is steady at 800 now and I can't get the surge to come back if I try.

*I don't recommend the 'Hammer Fix' unless you have already run out of options and tried adjusting the throttle with the idle screw.