Jeep 4.0 idle misfire issue.

[TapouT]

I'm stumped...I've got a 1996 Jeep Cherokee sport with the 4.0...it has a rough idle issue I can't figure out. The Jeep drives perfect going down the road. Smooth as can be with plenty of power. Sitting at idle at redlights etc the Jeep has a dead miss. I've replaced spark plugs with Champion copper plus gapped at 0.035, Belden spark plug wires, distributor cap and rotor button, removed the throttle body and cleaned IAC, throttle body and IAC housing with throttle body cleaner. Has new NTK o2 sensors. Has a stored code for catalytic converter but the cat is gutted. I've tried different types of gas. The Jeep does something weird on every start up I'm not sure if it's related to my idle issues? When the Jeep is turning over right as the engine starts it "misses"...*turn over* *turn over* *miss/hiccup* and then start. Is that related to a failing crankshaft position sensor?

 

[a_kelley]

sounds like it may be. check your fuel pressure with a gauge.

 

[Jody Treadway]

Hold a dollar bill at the tailpipe at idle. See if it sucks it up randomly. This would indicate a leaking exhaust valve which (among other things) could cause a miss
It's a free test that takes less than a minute

 

[mysterync]

I agree with Jody. Might throw a vacuum gauge on it as well!

Sent from my SM-N910V using Tapatalk

 

[3DCrawler]

Compression test will find it

 

[krehel24]

Make sure the distributor is not worn out...check for back and forth play in the shaft

 

[TapouT]

A new Mopar crankshaft position sensor fixed it. Thanks guys