Read this!! Not ur normal surge!! check out!

[bmxrider154]

THis is not ur normal idle surge! My n/a car has been doing this since i put the new motor in. IT will only surge for about 5 minutes or until warm. Weird. After that it idles perfect, idle motor fine, im thinking one of the gaskets maybe swelling, dont know. And also while im at it, on my 90 gst, i believe when i plug my isc motor into harness and remove from TB the pintle should move in and out when i turn key if it is good?? IT just kinda vibrates and does not move!

 

[Pro3racer]

Check to see if your EGR valve has a leak, just found out my entire gasket for the valve is blown out .

 

[bmxrider154]

no i checked egr, even put one in i had laying around to make sure.

 

[GTM]

no i checked egr, even put one in i had laying around to make sure.

Off the top I'm wondering if you don't have some adjustment or a broken/cracked vacuum leak associated with smog equipment. You report it runs well once warm but it's hunting for fast idle as it warms up. But because the this is set too high the ECU controls max idle speed it shuts down only to build again etc, etc.

Without more info that's the best I can do, have you checked codes or have damaged O2 sensor?

Cheers,
GTM

 

[bmxrider154]

no i dont have any codes, but yes it only does it until it warms. i havent checked the o2 yet, wasnt sure if that would cause it. Its weird though because it does it for the exactly same amount every time. weird! im going to check a few things this weekend and i will post any updates.

 

[Pro3racer]

Check you vaccum lines, all the basics, then start the car, and listen under the hood for any leaking air. Also pull the lines off 1 by 1 and feel for any pressure.

 

[GTM]

no i dont have any codes, but yes it only does it until it warms. i havent checked the o2 yet, wasnt sure if that would cause it. Its weird though because it does it for the exactly same amount every time. weird! im going to check a few things this weekend and i will post any updates.

It would seem it's a function of time and temp. I failed to suggest the gas cap seal, it's been a while since I've seen this so can't remember all the symptoms. Valving and sensors are put into play to purge gas vapors that are stored in the crankcase, tank, and the charcoal canister. If one of these hoses/circuits is open allowing raw air in the circuit you will get a high idle until the temp or timer turns the circuit off.

Another item to check is throttle switch which is know to fail.

Keep us posted.

Cheers,
GTM