Insane crazy problem.

[aceseverywhere]

95 3vze automatic

OK ready..............
I took of the intake manifold aka throttle body to get it cleaned at a machine shop. i installed it today. i start the truck and it fires just fine. i rev up the engine and at about 2000 rpms and then it drops...... the goes back up again at about 2000 rpms then drops. i checked for vacuum leaks from all the hoses alredy. and i quadruple checks the vacuum diagram already. what could this be.

 

[Hyde802]

Well...the intake manifold is not the same as the throttle body... The intake manifold is under the plenum.

But sounds like the typical surging idle problem with the 22res.

Whats it idle at before you rev it? Maybe try turning it down a bit.

Whats happening (I think) is that the engine is reving up, then the computer realizes that its going too high and kicks it back down... and repeat.

Hope that helps a little.

 

[aceseverywhere]

hmmm it idles at 1000 rpm upon start up. how can i trun it down? its the idle control valve located on the side of the intake. that thing you adjust with a screwdriver?

 

[Hyde802]

Yeah, Download the factory service manual, Its a stick on the top of this page, will tell you how to do lots of things.

 

[Clone of the Mean]

Mine kinda did the same thing. I could drive it 65 mph but it took EVERYTHING I had to do it. Turns out the MAF, AFM whatever you call it took a dump. Replaced it with a junkyard part and all is good. Also check your plumbing that goes into the intake plenum. Mine was all cracked in the grooves. It was hard to see. Good luck

 

[Hyde802]

^^ A good way to look for cracks, is to hold it up to the light and bend it, if the light shines through, you know its cracked.

 

[turboSR5]

Could be air in the cooling system, or low on coolant. Either of those makes your IACV freak out.