mudnut

i need some help, my 89 waggy's rpm's race sky high at start-up then settle back down it runs great other than this my engine is new and don't like the idea of it doing this before the oil pressure can come up i know it's prob. something simple that i'm missing thanx in advance

DEVILSTOY

i wanna say that could be normal just to warm the engine up at first , i work in a body shop and i notice even some brand new lexus's do that

RENIXBEAST

I would check for any vacuum leaks. I use starting fluid and spray it on any vac lines or fittings while the motor is running If it is leaking vaccum then the starting fluid will make your engine rev. The only other thing I can think of at the moment would be your idle control wich is located right next to your TPS switch on the throttle body.

mudnut

i had thought of that myself as well (see it with semis) but this isn't just a fast idle it literally races up sometimes to redline as soon as the engine fires you can here everything rattle because the oil pressure isn't there especially after setting all night

RENIXBEAST

I have an 89 also and it does the same thing every now and then. good luck.

fantic238

It's the Idle Stepper Motor on the throttle body. Try to unplug the connector before you start it.

mudnut

thanx for the help i'll try that when i go back out hopefully it's that simple

fantic238

That's only a test to see if it's that or not. If it doesn't rev up you need a new stepper motor.

mudnut

that didn't work all that happened was the rpm's stayed up and didn't drop
could the stepper still be bad aka not moving fully or to far which ever the case may be? i've chkd for vac leaks and my fuel pump ,filter, and injectors are all new driving me crazy

fantic238

Do the test again when the rpms are normal. You unplugged the connector with the stepper motor still open.

mudnut

sorry about that i was postin at the same time you did didn't mean to sound redundant kinda new to this forum thing

mudnut

that did it rpm's didn't climb i'm so happy i'm goin to get a new one here shortly THANX HEEPS

fantic238

Hey no problem, i'm here to help you.
and welcome to the forum.

RENIXBEAST

o I so called that one, its usually that or a vac leak.