thesplintercell

2000 xj sport 4.0l

Idle is whacked. I've been searching for months and I'm no where. It starts second try everytime. Starts idling at 1100 after I start driving it goes to 2200 when I slow down to a stop it goes back to 1100(sometimes).

I do not have a vacuum leak. I'm thinking now it's a fuel pressure problem. I did the injectors over a year ago. And maybe I have a bad oring. But before I start the car I have checked if there is fuel in the fuel rail, since it only starts second try, and there always is fuel up there. So maybe it's my fuel pressure regulator or even my fuel pump. But I'm pretty sure both of those are in the tank and I'll have to just buy both and commit a whole day to checking. I'm just hoping for some Input from some smarter people.

landude

If it was a fuel pressure problem I wouldn't think you would have such a high idle.
Have you ever taken of the throttle body and cleaned up everything inside and attached to it? Just a thought.

XJwonders

I'm subscribed to this thread. I have a WJ with exact same problem as the OP. I wanna see if someone's solution will apply to mine too.

thesplintercell

Yes I have cleaned it and replaced it and cleaned and replaced the air filter.

thesplintercell

And I've cleaned and replaced iac and TPS 2 times on each

thesplintercell

And the map sensor and the elbow attatched to the map sensor also had been replaced

XJwonders

Did u replace with genuine mopar sensors?

thesplintercell

Ughhhh. No. It's really that sensitive to mopar?

XJwonders

Yes. Most aftermarket sensors actually doesn't come close to mopar's quality. I had a bwd sensors and it didn't solve anything so I went and bought mopar sensors and problems went away

landude

Yes indeed.

Roler

[QUOTE=thesplintercell;2760256]2000 xj sport 4.0l

...Starts idling at 1100 after I start driving it goes to 2200 when I slow down to a stop it goes back to 1100(sometimes).
..QUOTE]

What do you mean with "after I start driving it goes to 2200"?
You mean the idle when its warming up?
If your TPS is an aftermarket one, your problem could still persist...
How did you check for vacuum leaks?

thesplintercell

after it's warmed up and I have started using the accelerator it's goes to 2200. When I stop it goes back down to 1100. I checked for leaks by spraying carb cleaner around hoses. And actually the 3rd time I checked I lost my mind and just sprayed the entire engine bay with carb cleaner hoping it would ignite. Yea. I'm not happy.

thesplintercell

Ok. After I reach a speed of 17 miles per hour my idle goes to 2300rpms. And when I go below 17mph it drops back to 1100 rpms. Not all the time. But very consistently. Is there a speed sensor in the IAC?

Rogue4x4

Well, that's clear as mud...if you are driving you are not at idle...are you putting it in neutral after reaching speed or something? The idle problem you describe is sounding like your IAC, but your wording is very confusing...if you have cleaned your IAC, have you tried replacing it with a known good one yet?

Roler

This is still confusing indeed.

But to asnwer your question: no, there is no speed sensor in the IAC.
But your IAC is also in use if you for instance let your foot off the accelerator while driving down the road. In that case, say you're going 50 and take your foot off the pedal, your rpm's will go down, but NOT as low as when you just idle in the driveway. Is that answering your other question maybe?