Idle air control valve? (1 Viewer)

[win1894]

Hello gents

1 FZ FE question

A few weeks ago I started having problems on start up, which I thought was a head gasket/ cracked head (was starting strange; rough mainly and bogging down, white smoke) so I had it fluid tested and nothing

Gave it a new set of leads and plugs thinking it may be a spark issue, new air filter too still happening

Yesterday morning it was quite crisp and as I started it up my revs went up to about 1000 then down to 650, the needle started to bounce and it started to miss for about 5 seconds then stayed on 650, I thought this was odd as normally it will sit around 1200-1500 until it starts to warm up then will gradually drop to somewhere between 650-800 idling while warm

sometimes when being started the check engine light will stay on for a second like it’s being starved

Does this sound like an An idle air control valve?

 

[gummycarbs]

I don't think I've yet heard of an IAC that's actually gone bad.

Warm idle in park or neutral should be 650 +/- 50 RPM.

If I were you, I would probably look at the throttle position sensor and then move on to vacuum hoses and cleaning the intake. It's a fairly complex system and one blocked passage or leaking hose can cause symptoms that look like something else.

 

[Kernal]

What model year is your 80 series?

 

[win1894]

What model year is your 80 series?

1994 GXL

 

[Landseer]

The rubber air intake tube that goes from the air filter to the throttle body is known to degrade after 20 odd years. Cracks in the tube will let unmetered air into the engine and can definitely produce symptoms similar to what you're seeing. Easy way to diagnose this is to wrap the flex join in the intake tube with duck tape and see if that fixes your symptoms.

Might not be your problem but its easy to check.