Odd Start-up on 87GT

[Mike85000]

Hey Guys,

My stang is a 87 GT. Bone stock. 180000kms. Engines runs great.

The car is a daily driver, no problems to speak of.

Every once and a while, when i fire it up, it will rev up to anywhere from 2000-3000RPM and hold for a second or 2 then drop to normal idle.

Most of the time, it starts normal, crank, it fires up to about 1500 and immediately drops.

Any ideas what could cause this intermittant rev up at idle?

I have pulled the codes and got 2 that are related to the EGR system. I think a 94 and a 44.

Anways, just wondering if anyone has had this happen to them, or has an idea of what is causing it.

Thanks,
Mike

 

[jk351w]

If you have been experiencing this during colder temps it's perfectly normal.

 

[Mike85000]

It hasn't chnaged due to the weather, just random startups it will happen.

Basically, it sounds like i started it with my foot on the gas, it instantly spikes to around 2500rpm upon firing, then a second later will drop to normal idle. Could this be a TPS going bad, it never does anything funny when driving...

 

[jrichker]

Check/clean the IAC.

See "Surging Idle Checklist for help with all your idle/stall problems. The first two posts contain all the updates to the fixes. I continue to update it as more people post fixes or ask questions.

 

[Mike85000]

jrichker,

Do you think that a dirty IAC woulkd cause my problem? I don't have a problem with it surging at all, and since it is spring loaded to the closed position, it makes me believe that the computer is causing this quick rev when i fire it up.

I will pull it off and give it a clean just in case though.

 

[ninety15.0]

If i remember correctly those two codes are for inoperative thermactor systems, left and right? Did you remove your smog pump?

 

[Mike85000]

Smog pump is still in. As well as the factory H with cats. Not sure how well it works though, no smog tests around here. I assumed the codes were unrelated to my problem. Ill have the clean the IAC and see if it helps, problem is it happens intermitantly so its hard to see right away if the problem is fixed.