Ok, so last week my 90 renix got a 98 motor, 99 intake and exhaust, it's all wired up and running like a dream. Two thing happened though. My idle air controller was bad from the get go, so I simply left it unplugged and manually adjusted it untill it idled at 800ish rpm. I used the same 'bad' iac on the new motor and intake, but it's idling around 1500. The other thing that happened is on the old motor removal, I neglected to remove the o2 sensor, so it got busted. So here's the questions

1- could not having the o2 sensor make the idle high? I know it helps meter fuel delivery, but does it do it to where high idle will happen?

2- when first started up, the jeep idled at 1k, then rises the idle as it warms. I'm assuming this is due to no o2 sensor so its running on presets once it gets to operating temperature?

I'm going to get a new iac and o2 come Friday, just curious if these two things have a correlation

 

Vacuum leak and the pintle on the IAC is not adjustable manually, you probably broke it.

 

It was malfunctioning beforehand, idled erraticly. Also, pintle works on a worm screw. Dunno if it's broke or not but I believe it is. Either way it's unplugged so it is no longer adjusting idle. I'm more curious if the lack of an o2 sensor is making it get more fuel then needed

Anyways, I don't see or hear any vaccuum leaks, only vacuum ports are for the brake booster, and fuel rail. All other ports are capped

 

More air = higher RPM
More fuel = rollin coal / bog city

 

Fair. Wasn't trying to be rude in the last post btw

 

Parsnip, I'm with Turbo in thinking you've got more air leaking into your engine from somewhere.

 

It'll be interesting to see if the new o2 sensor changes the idle rpm at all. My guess is that it will still be high.

 

Well you need a new IAC and O2 sensor but it's time to get out the spray bottle or carb cleaner and find that leak. Check around the TB, head mating area (you used a new gasket for the manifolds-to-head right?) and check for any missing vacuum hoses. I know the '99+ intake has an additional fitting that prior models to not use.

 

Yes, New gaskets werre used, but since you say Tb base...might have something there. I shall return!

 

Which intake gasket did you use?

And no, O2 sensor will not cause a high idle.

Get all three or so grounds back on to a shiny clean dipstick tube stud of that new motor?

 

Used the 98 intake gasket, since its a 99 intake/exhaust.

Grounds were actually 're done, ie factory end was cut off, the stud on the block was cleaned while it was out etc. I'm getting like .03 ohms between the intake and negative terminal if that's what your huntin cruise man

 

That's all good then.

Have you sprayed for vacuum leaks?

 

Yes. And suprisingly, I blocked off the iac and it ran barely. Throttle butterfly doesn't seem to be sealing completely

 

Post 14 in my Tips.....

 

CCV orifice is supposed to let air in, as well.