1995 454 High idle

**Xenon** · 12-29-2014

It's very consistent which is why I assumed the iac was doing its thing. I did have my autoprom hooked to it and the dash tach read ~100 rpm higher than the data stream indicated. Coolant temp showed just shy of 180 and iac steps were at 29 I think. And it said it was commanded at 29, so seems to be working?

**Xenon** · 01-02-2015

No ideas?

**fastacton** · 01-02-2015

Is the throttle kicker working properly? I haven't actually hooked one up, so I don't know exactly how it's supposed to work, but I think if it's not getting proper vacuum, it'll cause a high idle. What's your TPS reading at when it's at idle?

**tayto** · 01-02-2015

Originally Posted by Xenon

It's very consistent which is why I assumed the iac was doing its thing. I did have my autoprom hooked to it and the dash tach read ~100 rpm higher than the data stream indicated. Coolant temp showed just shy of 180 and iac steps were at 29 I think. And it said it was commanded at 29, so seems to be working?

confirm idle with another tachometre. i have a digital timing light that displays rpm, i always use this or a scantool to verify the in-car gauge. Not uncommon for them to be off on the "older" stuff. get engine hot and check what iac counts are. I like to set mine 5-15, target is usually 10. You can do this by adjusting the throttle plate stop screw, most likely will have to remove tamper plug. I like to make an adjustment then turn vehicle off and wait 10 seconds and go again, if you make too big of an adjustment it can bump the ecu out of idle mode and into cruise, making the adjustment false.

**Xenon** · 01-03-2015

Throttle kicker works. I don't see any place where you can adjust the throttle blades on this unit... The one on my '87 had a little cap you had to knock out with a set screw under it... This one has an indent in the casting where the cap would be but it is cast solid...

**fastacton** · 01-03-2015

I've never seen one cast solid. Are you sure it isn't a cap?

**brian617** · 01-03-2015

Being that the idle adjustment plug hasn't been removed and the IAC is commanded at 29 steps I think your barking up the wrong tree in regards to the throttle blades being the problem.

Try looking for something that is commanding the increased idle speed, ie grounded AC signal to ECM.

Posting a data log will sure help too.