kurama49

It did it once, then the rest is all high rpms.
And the tps is brand new yes, and adjusted properly.

also.. is the IAC supposed to have a gasket between it and the throttle body?... my new one never came with one, and the old one didnt have one.. but just now skimming through your renix writeup i noticed this
"wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged "

Could this be the problem to all of this?, and can I make a new gasket out of gasket paper

cruiser54

It's an o-ring, and that could be an issue.

kurama49

ok well, the O-ring is there then, so.. could it be my homemade gasket mabey? [my old one fell apart when i took the TB off.]

cruiser54

Maybe. That should show up by spraying throttle body cleaner around the throttle body base.

kurama49

Well I'll just have to wait till tomorrow to see what the new gasket does

kurama49

Well, I put the new gasket on annd... nothing. Still idles high. I double tripple checked all my vacuum lines, all my connections, I checked the upper intake bolts, their all tight as can be, EGR valve is working ok, IAC is working, TPS is adjusted to the right voltage, Throttle body is clean as a whistle, All the bolts are as tight as i can get them....

ARGH I'm running out of ideas for what in the hell this could be. Its driving me insane! I've allready missed mudfest cause of it, something I've been waiting 4 MONTHS for.

So, a list of everything I've replaced or done so far:
Replaced IAC
Replaced TPS and adjusted to 0.834 volts. Using a reference voltage of 4.91 volts
checked all the Connectors for resitance, with the meter only going as high as 1 ohm
Cleaned the throttle body to the point where it shines almost as good as chrome
Replaced the throttle body gasket with a new one
WD-40'd all of the throttle linkage
Replaced my main ground cable, cleaned the connections for the chassis ground and cleaned the dipstick stud area.
Replaced the plug wires, rotor, cap, and rotor button
Checked the MAF by using the one off my parts jeep [same result.]


So, I'm at a loss. If I dont have this port plugged at startup it idles at 2,000RPMs then creeps to 3,000RPMs [somewhat quickly]

[also this is just a pic off the internet]

And there is a INSANE ammount of vacuum from it.

So... yea.. running out of ideas.. My brain is starting to hurt from thinking so much :x

Radi

Taking a longshot in the dark here, but the ecm may think your rpm's are dropping and opening the IAC to bring them back up.
It gets RPM information from the CPS, which may also be causing your misfire. Ever checked the CPS output voltage? I believe your year can be checked with a voltmeter. Plugs and connectors nice and clean?

When it's idling normally, unplug the IAC to freeze it in position and see if the idle speed remains normal after a short drive. If it does, something is telling the ecm to speed up the engine. Will have to weed out the sensors one by one to find the culprit. If they're all functioning normally you may have a failing ecm.

cruiser54

I think we're on to something here. Someone probably messed with the throttle blade stop screw at one point.

Cruiser’s Renix Throttle Body Butterfly Adjustment
Okay. Let's start from scratch. First off, that's not an idle adjustment screw. It's a throttle butterfly stop screw. It's purpose is to allow the butterfly to be as close to completely closed as it can be without binding or wearing into the throttle body. It was never intended to be adjusted in the field. But, Uncle Bob didn’t know that, did he?

Engine off. Back off the butterfly stop screw with a 3/32" allen wrench until the butterfly is completely closed. Now. turn the screw in until the FAINTEST movement of the butterfly opening is detected. This can be done more easily with the throttle body removed. If you remove the throttle body, be sure to replace the gasket underneath it after thoroughly cleaning the old one off.
Revised 07/07/2012

kurama49

Tryed that, even with it fully closed completely 110% it still idles high :/

I've been taking a little break from the jeep to tinker with my old chevy, so i do get frustrated at the jeep and do anything stupid to it

kurama49

Well, time to revive this thread, as the problem is still there. I've just been taking a break from the jeep and been spending more time working on my chevy.

So, It still idles high when the IAC port is unplugged, But, we also found that, if you cover the throttle blade opening with your hand and unplug the IAC port the idle still goes up, so my friend said that ment it was getting air on the passenger side of the Throttle body? I'll be getting a new [to me] throttle body off a friend tomorrow to try.. And if thats not it, a family friend is going to scan it with his OBD1 scanner this friday. hopefully i can get it running good again soon... Because driving THIS


Is draining my wallet, [$40 to go 100kms/62 miles ] Giving me headaches [hitting my head off the roof, and dual straight through mufflers] and giving me carbon monoxide poisioning.... [exhaust leaks...] So, I need to figure out what the hell is wrong with my jeep soon. I also in the meantime, checked over all my grounds and what not again, and replaced the dodgy battery with a Red-top Optima.

So current suggestions from friends are:
Wrong IAC?
A nick in the throttle body somewhere causing it to suck air
Bad throttle body completely
And intake manifold gasket...

But alot of people are saying it could be the throttle body.. I dunno I'm still stumped

cruiser54

Cruiser’s Renix Throttle Body Butterfly Adjustment
Okay. Let's start from scratch. First off, that's not an idle adjustment screw. It's a throttle butterfly stop screw. It's purpose is to allow the butterfly to be as close to completely closed as it can be without binding or wearing into the throttle body. It was never intended to be adjusted in the field. But, Uncle Bob didn’t know that, did he?
Engine off. Back off the butterfly stop screw with a 3/32” allen wrench until the butterfly is completely closed. Now. turn the screw in until the FAINTEST movement of the butterfly opening is detected. This can be done more easily with the throttle body removed. If you remove the throttle body, be sure to replace the gasket underneath it after thoroughly cleaning the old one off.
Revised 07/07/2012

cruiser54

Then, readjust the TPS on the engine side, flat 3 wire connector, to 17% of input voltage.

kurama49

Done and done :/ still idles high [well to the current throttle body, I'll do all that when i try the new one tomorrow]

kurama49

Well, i fixed my high idle! somewhat, I put on a different throttle body, pluged it all in adjusted everything, I started it, and it only went to 2,000 then settled back down to 900rpm. So, i took it for a drive.. the sputter was still there, so i parked at our useual parking spot, waited for a bit, and went home, I decided when i got home to see if it was pouring out black smoke like before, so i went behind the jeep and noticed there was white smoke coming from the tail pipe, and then i heard something leaking.

So, i shut the jeep off, popped the hood, and there was coolant pouring from the rad cap [brand new] the overflow bottle was over flowing, and there was steam everywhere So.. what would this mean?... mabey the sputtering and this are linked? bad head gasket mabey? we'll be doing a compression test tomorrow to check...

codenameanimal

I had this exact same issue on my mother's wrangler with the 4.0 it would idle at 3000 rpms like normal and would randomly drop in rpms and almost stall out. Replaced everything like you did to find out when replacing the intake manifold gasket that some of the o-rings on the fuel injectors were not there. I replaced those and voila fixed. A lot of times high idles are from vacuums leaks may not always be hoses I have had to fix weird idle issues on other vehicles from loose parts to worn or nonexistent gaskets to missing or shot o-rings and it seems once in a blue moon it is a bad sensor. Hopefully this helps and good luck