Another "Surging Idle" thread...

[Repostyle]

This is not a "How I fixed", this is a question.

This started after I did my auto to t-5 swap. The engine is a ton more responsive to the throttle after the swap so I think it might be releated.

Here's the problem, the car idles fine when I start it up cold and warm, if I rev the motor and let it drop back to idle it surges for a bit but usually settles down quickly after maybe just 1-3 surges and that's with clutch out in neutral. But when I'm driving it and come to a red light or something and push the clutch in it surges so bad it dies every time. If I leave the clutch enguaged and brake until the motor comes down to about 800 RPM and then push the clutch it idles fine.

So the question is do you think it's the IAC not reacting quick enough for the faster drop to idle speed or something else?

Still have the automatic ECU in the car which I hear is perfectly fine but just thought I'd throw that out there.

 

[jrichker]

See the "Surging Idle Checklist for help with all your idle/stall problems.

The quick and easy way to dump the codes is in there too, and all you need to do it is a paper clip! The first two posts contain all the updates to the fixes. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.

 

[4rdnut]

do you have the vss sensor hooked up? if not thats your problem.

 

[Repostyle]

do you have the vss sensor hooked up? if not thats your problem.

VSS = Vehicle Speed Sensor? If that's what that means, I'm not sure how that would be releated to my problem, but it's hooked up and the speedo works fine.

 

[Chuckman]

VSS = Vehicle Speed Sensor? If that's what that means, I'm not sure how that would be releated to my problem, but it's hooked up and the speedo works fine.

the computer uses it to raise the idle as you slow to a stop, so that theres a smaller rpm "jump" if youre just downshifting, or have to accelerate again before stopping. the sensor CAN go out, the checklist above will give the info on how to test it. and fyi, the speedo and vss have nothing to do with each other, other than the fact they both hook up to the trans at the same place, the fox speedo is entirely mechanical.

 

[Truckie]

Hey I just fixed this problem on mine last week....

It would only do it with the AC on but when I pushed in clutch for a stop sign or light, it would surge up and then drop off and stall. I took off what I call the bypass valve. (top left front of intake assy) and sure enough it was gunked up with junk. 2 bolts off,A few sprays of carb cleaner and some q-tips,.... problem solved. I learned this trick on my Crown Vic police interceptor a few years ago when it would not stay running after I started it unless I kept my foot on the gas a bit.

hope this helps you...