Jumping Idle

[Mayt13]

Hi guys,

I'm new here, I just got a 1989 lxi with the fuel injected 3 valve A20 and it runs great. Only 88k orginal miles on it with no upgrades/tinkering as of yet. Bought it of a little old lady who'd had it since it was new. Now its having a slight problem. Once it has heated up the Idle will climb to around 1500 and then drop back to 1000, repeatedly. Is this a vacum issue? Do these cars have an EGR valve like my camaro?

Just bought the manuals and will tear into it next weekend. Any imput is appricated ;)

[2oodoor]

Welcome!
I know that if the coolant system is a little low or has air pocket the idle can be annoying. I would top off the coolant and bleed the air out at the bleeder by the thermostat. Do a throttle body spray cleaning too, thats maintenance.

[ghettogeddy]

I'm having the same issue and I think its the idle air control valve.

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[89T]

I'm having the same issue and I think its the idle air control valve.

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When i had that problem all i did was clean the iacv with carb cleaner. That's all it took.

[ghettogeddy]

Ya I already did that.. But I think it broken so I'm just gonna replace it.

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[Dr_Snooz]

Both a vacuum leak and low coolant will cause this problem. If the coolant is low, be sure to fill and bleed the system properly or bubbles will be trapped in the system and the problem will continue.

[Jafir]

As has been mentioned, first thing to check is coolant level.

If it were my car, then I'd check the base idle speed. I had an 86 lxi that the idle adjust screw would back out after some time. I started putting a dab of Hondabond on it it keep it set.

If that is ok, I'd check the thermo wax fast idle valve. The factory manual says its not adjustable, but the only option is to replace it, so feel free to adjust it.

88-89 have a iacv, which can probably be cleaned, but I'd think it would cause a low idle, not a surging idle, unless maybe it's stuck open.

[Vanilla Sky]

If you haven't fixed this already, you can take both the iacv and ficv apart and completely clean them. It helped me out. Of course I'm getting a rev hang that I attribute to one of those valves now.