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Rough idle, then high idle when warm.

Renegade_Azzy

NAXJA Forum User
Location
Finleyville, PA
The 96 is making fits. It runs well enough, temps all in a good place. Once it warms up, to around 130 degrees, the idle smooths out. But it increases from 790 to about 1100.

After driving, when I take it out of gear, it bumps from 840 to 1400.

(Numbers all pulled from my tablet running Torque Pro with a USB scantool.net scanner)

recently done:
New APN manifold
New downstream O2 (Bosch)
Newish Upstream O2 (NGK, 3000 miles)
New speedo gear, 32 tooth
New high flow cat
Cleaned the idle air flow controller and the socket, as well as replaced the o-ring.

This has been happening for a bit. If I pull vacuum hoses, RPMs change, all but the one going to the valve cover. No codes. Manifold and throttle body were cleaned when it was all out of the jeep for the APN.

Dit cap is newer, was on here when I got it. Same with plugs and wires, they have about 3K on them all as well. It dint drive much because of a wiring problem (see my money pit build thread). Newer timing chain, newer whole cooling system. CPS is a NAPA brand, and is about 2500 miles old.

If I unplug the IAC, nothing changes. Is that a bad sign? (If I pull the CPS, it stalls.. go fig
laugh2.gif
)

The TPS is new to when I got the Jeep, but was an Advance purchase
 
Check for loose upper and lower intake manifold bolts when cold.
 
I had variable idle issues. I found a leak at the intake manifold using a spray can of starter fluid. The idle issues varied as things heated up and cooled down, the slight gap would open/close as things expanded and contracted.
 
I had variable idle issues. I found a leak at the intake manifold using a spray can of starter fluid. The idle issues varied as things heated up and cooled down, the slight gap would open/close as things expanded and contracted.

Not a bad idea. To be honest, spooked to try with the chance of lighting things on fire.
 
Not a bad idea. To be honest, spooked to try with the chance of lighting things on fire.

Trigger sprayer with water does the same thing, it just lowers the rpms instead of raising them when it finds a leak.
 
Doesnt sound like your distributor but you can buy a inline spark plug test kit or you can use a screwdriver but that way hurts a little. The color of the spark will tell you if you have a good distrib, coil and cables.

Pull your sensors from your TB and clean them with electric connection cleaner. Yank your CPS connection and clean it too. It should be attached to the last bolt in your fuel rail. If that doesnt help start googling how to test the sensors. Something is out of whack. Usually if you have an exhaust leak you'll notice it before it warms up.

I'm not a big fan of non OEM sensors but thats just because I went threw 2 TPS until I bought a MOPAR one and BAM codes went away.... until I screwed something else up lol
 
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