95 GT High Idle

[Wood's 5.0]

A man I know has a really nice, Laser Red, '95 GT 5-speed and it will not idle down below 3,000 RPMs. He is an older gentleman and has owned the car for a long time. The car is in great shape and has not been abused or anything like that. He changed the IAC, albeit it with an Amazon or flea-Bay unit, with no effect. He can even unplug the IAC and that doesn't change anything. Tapping the throttle only raises the RPMs and it goes right back to 3,000. The engine runs just fine; no skips, loss of power, rich smell, etc. He stopped by the house and asked me if I knew anything it might be/he could look for. My response was it could be a number of things. I rattled off a few possibilities for him to check, i.e., vacuum leak, TPS, MAF, TB butterfly position, etc. Any other things y'all can remind me to point him to? Been so long since I have been into the troubleshooting game. Usually, with a Ford, any idle issues are a result of a faulty IAC. Usually goes the other way, though, and won't idle/stay running at all. Thank you in advance for any help or ideas you will offer.

 

[white95]

Could try a base idle reset:

 

[RAU03MACH]

base idle reset
vacuum leaks

 

[Wood's 5.0]

@white95
Thank you for the reply and link. I mentioned the base idle reset but had forgotten the procedure. Since then, he said he unplugged the MAF and it idled right down. I told him to try cleaning the element first or replace it with a known good one if that didn't work and see what happens. Thank you, again, for the reply and link.

 

[ttocs]

time for a smoke check

 

[chindennis]

1995 SVT 5.0 Cobra can't get idle down from 2500 rpm. Tried engine reset with no changes with IAC or spout disconnected. Headers start to glow red. Replaced throttle body, IAC, throttle body, MAF and sensors, injectors, distributor, timing chain, IEC, plugs, fuel pump, cap and rotor. Any suggestions appreciated.

 

[95opal]

1995 SVT 5.0 Cobra can't get idle down from 2500 rpm. Tried engine reset with no changes with IAC or spout disconnected. Headers start to glow red. Replaced throttle body, IAC, throttle body, MAF and sensors, injectors, distributor, timing chain, IEC, plugs, fuel pump, cap and rotor. Any suggestions appreciated.

Sounds like a massive vac leak

 

[ttocs]

if the headers are glowing I would take the 10 mins it takes to check the timing.

We have had a couple of people finding leaks in their throttle body by the TPS or around the butterfly valve that could cause this. It would all be air in the system after the maf.

 

[chindennis]

Thanks for the sound replies! "ttocs" was correct in checking the timing. I was surprised that replacing a slack timing chain would result in timing going way, way off! Since the idle was so high, I manually guessed at retarding the distributor a little at a time until the RPMs dropped and I was able to see the timing marks. Thanks for a very helpful forum!

 

[ttocs]

cool I am pretty sure I learned that here from someone. Most of what I have learned was here.