HELP! Groaning and surging

TheDog

Registered User
This problem started months ago and I'm finally getting around to posting about it. I've got a 1990 SC auto. I'm thinking this problem started shortly after I installed my magnaflow resonator and Flomaster resbacks. Of course the problem is intermittent too. Car starts up just fine. Usually within 15 seconds, the car will groan loudly (sounds like air resonating through something under the hood but I could be wrong) and surge up to a 1250rpm idle. It'll stay like that for a while then the groan will go away and the idle will drop back to 700 or so where it's supposed to be. If I drop it in gear, hold it for a second then put it back in park, it'll USUALLY force the groan and rpm surge to stop. But sometimes it won't stop it. You can imagine how hard I have to apply the brakes to hold the car still. It'll do it periodically while I'm driving too. So while I'm cruising, the groan may come on and force my tach up to 1250. I'll shift into neutral, the engine will soar to 1700 for a moment (probably because there's no load all of a sudden) then drop to it's correct idle. I'll put it back in gear and it'll behave for a short while then repeat.

The engine is all stock. What gives? Any ideas? Thanks! :confused:
 
one thing to look at is the IAC valve. it could be sticking. i would replace it. mine went out on my 89 sc, it cost about $65 at advanced auto parts. hope this helps you out.
 
does it make a goose sound when you turn it off? If so, that usually indicates the IAC is sticking/Bad.
 
Yes!

YES!!!! It DOES make a goose sound when I cut off the engine! "Arrghggroan...." for about 2 seconds after engine turned off. Would that contribute to the surging as well?
Ok so what is it (what's the acronym), where is it, and can I replace it myself? What tools would it take? I'm not too mechanically savvy, but I can change my own oil and I did stay at a Holiday Inn Express last night. :D
 
Ok which black thingy on the right is it? Is it the one sticking out farther closest to the oil fill cap? Or is it the one behind it that doesn't stick out as far? It looks like I'd have to remove both if it's the inner one. Will I screw anything up? I attached a pic.
 

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Yep, the old bad Idle Air Control valve (IAC). Just go and get a new one from your choice of auto part replacements and then match it up with the one under your hood that's bad. Goose honk is fuuuuuuuuuuuuuuuuuuunny!:D
 
............. IAC
wl2tv206003.jpg
 
Thanks for all your help! I'll pick one up tomorrow and let you know how it goes!! I think you guys just saved me a gajillion $$$.
 
It seems to have worked! It idles fine, doesn't misbehave when I change gears or rev the engine. Just lays at 700 or so where it should and NO dying goose groan! I haven't really driven it because I'm working on my brakes but from what I can tell, the ICV replacement fixed it! THANKS!!!
 
heads up for cheaper future repair, thats the same valve that they use on most all 3.8 v-6's. next time head to pick and pull for about $3. :)

almost forgot, you can find those on rangers to :)
 
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