Occasionally when I start my xj it will be revd like I've got the pedal slightly down...even if you put it in drive or neutral it is still revd....don't think its the tranny cause its in excellent shape ...help!

 

Mine does this from time to time and I'm starting to think it might be a leaky injector - only since I've fixed or replaced almost everything else. Maybe check the TPS and IAC? Could be the IAC sticking from time to time if you haven't cleaned that out at all...

 

Iac.

 

Im a noob fellas...what is an IAC where is it and how do I clean it? Haha

 

Idle air control. It is on the front of the throttle body left hand side. There is a 3 wire connector going to it. Mine had a bad o ring. Search it on here or Google.

 

Thanks bro...I read a write up on how to clean it...ill do it Monday and let y'all know if it helps

 

Make sure it seals up good. If air leaks in it won't work right.

 

Is there a gasket or seal on it?

 

After researching it I have found some people saying it had a gasket others saying there is no gasket ...also read that you have to gauge the distance from it and the tb...help please

 

I would replace your tps that's what I did on my 88 and it now its fine

 

Mine was doing that awhile back ,and I replaced the tps and now its fine. If its still doing it after you check the iac ,I would check I would check.that

 

Anyone 100% on if there is a gasket or if the iac has to be gauged?

 

There is an o-ring.100%. I just put it back in 5 minutes ago.

 

Ok..thank you...is it fragile?? Or does it require a sealant to put back on?

 

definitely an o-ring on the IAC where it mates with the throttle body. IIRC it's pretty thick and a new IAC comes with a new o-ring. If your o-ring is cracked I'd start by replacing just that since it a cracked one would leak air and cause erratic idle. I cleaned mine up good when I did the rest of the Throttle Body but it didn't fix the idle it so I replaced it. Idles much better now so it wasn't sticking, just plain died. It's a little motor that pushes a plunger in/out of the air chamber in the throttle body to allow some air through when you don't have yer foot on the gas. Kinda like an automatic choke. You'll see when you get it apart, made a lot more sense to me when I took the thing apart and saw the inside!

The older XJs, 84-90 I think, have some kind of adjustment on the IAC which is a little different than the one for my 96 which does not adjust. I haven't messed with that but if you get a new one I think there is some kind of adjustment. The pre-90 guys on here will definitely know!

X2 if the IAC is working fine then I'd check the TPS next (also on the throttle body)