'93 Convertible Surging at idle

[JasonP]

I decided to fire her up last night before I put it back in the garage and noticed it was surging pretty bad at idle, this is the 2.0l L4 engine, I can open the throttle a bit and it sounds beautiful but just letting it be it'll surge like no tomorrow (hasn't stalled out yet). I've noticed when I rev it up a bit it takes a little bit for the surging to come back and given the sludge I found everywhere else in this car I'm thinking it's the IAC just needing a good cleaning (or replacing).

Where is the IAC on this engine and what's the best way to get to it?

Also a followup question if I may, I've been trying to figure how to flush the heater core for a while now but it seems pretty inaccessible/buried what's the easiest way to go about doing this?

EDIT: for those who say "just get a service manual", I've ordered it but it wont be here until 02/10

Thanks,
- Jason

 

[melsg5]

if you can access your throttle body that is where the IAC is located. I take it you cannt get to the heater hoses easily in the engine compartment?

 

[JasonP]

if you can access your throttle body that is where the IAC is located. I take it you cannt get to the heater hoses easily in the engine compartment?

I'll take a closer look this evening, but yes the heater hoses are buried and don't look easily accessible was hoping to catch someone who'd done it and would know an easy way around it.

 

[92 Sunbird LE]

Welcome to the Sunbird Forum, see pic below for IAC location.

You can access the heater hoses on the drivers side above the transmission, they connect to the heater core inlets which are easier to see under the steering rack from under the car.

Doug in P.R.

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[JasonP]

Welcome to the Sunbird Forum, see pic below for IAC location.

You can access the heater hoses on the drivers side above the transmission, they connect to the heater core inlets which are easier to see under the steering rack from under the car.

Doug in P.R.

Awesome info, thank you. I took a look under the hood when I got home for lunch ~2 hours ago and immediately saw the IAC doh took it out and it's pretty nasty, completely black and the spring behind it is worse I cleaned it off with some carb cleaner til it was nice and copper looking again and placed it back, when I turned it over it sputtered a few times then died. Started it back up revved a bit and it's still surging, doesn't seem like it affected anything.

That being said it could still be the IAC given how it looked I'll grab a new one soon, until then anything else I can try to diagnose the problem? (short of replacing tons of things)

Regarding the heater hoses: I guess it'll have to wait until I can get a new jack mine bit the dust recently, thanks for the info though!

 

[melsg5]

did you look inside the part of the throttle body where the IAC is mounted to see if it is also nasty looking?

 

[92 Sunbird LE]

After you clean the throttle body also as Mel replied, disconnect the battery for 1/2 hour and restart. It takes a couple of days for it to relearn the idle.

You may want to Seafoam the car also.

P.S., Ramps are easier ....

Doug in P.R.

 

[JasonP]

did you look inside the part of the throttle body where the IAC is mounted to see if it is also nasty looking?

Yes absolutely, I always just clean everything when I clean an IAC since it's RIGHT THERE and I have all the things I need.

After you clean the throttle body also as Mel replied, disconnect the battery for 1/2 hour and restart. It takes a couple of days for it to relearn the idle.

You may want to Seafoam the car also.

P.S., Ramps are easier ....

Doug in P.R.

I actually thought just that when I got home and, while disconnecting the battery, I noticed the neg terminal was a bit loose as well so I turned on the headlights on high-beams and started it, sure enough they dimmed. I went ahead and reset but also made sure to tighten the terminals and this seemed to stop the surging almost completely now it's just a rough (read: loud) idle which I expect as I have been told a gasket was forgotten between the cat and the muffler.

Ooh sea-foam I used to use it on my 04 land rover, loved going through town freaking people out with all the smoke Will do, thanks for the advice everyone!

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