Im on the road using crappy mobile web so i cant search...what would cause my jeep to just shutoff without warning? 110k on engine, recent full tuneup, new CTS and iair charge sensor. it has only shutoff completely once when sitting still in park. it has acted like it wanted to die twice while idling in drive. when it did this, the voltage meter would drop to about 10 and it would run kind of rough. otherwise, it runs smooth as silk with no issues. any ideas?

 

idle air control

 

TPS?

 

The #1 cause of random dying is the "crankshaft position sensor"

It is the most common sensor failure on the Jeep 4.0

The voltage meter shouldn't drop that much. I would recommend refreshing all of your engine grounds. This preventative procedure is often ignored until symptoms occur.

 

Would the CPS have an impact throughout the entire driving range or just @ idle? I have never had a problem while actually moving, just at a standstill.

 

your cps is on the way out , at above idle speed the sensor produce higher voltage ,which keeks engine runnung, when you drop to idle the voltage drops too far and engine dies. over time the sensor will get so bad it will stall on highway also. get a new cps.

 

if the cps was bad it would not start

 

I said it is on the way out, if it was totally bad ,it would not start, when they start failing they can give random hesitation , stalling after getting hot, no start after hot soak, and finally when they give out your engine gont start @ all. you will have no spark and no injector firing, because crank together with cam sensor tell computer when to inject fuel and when to fire coil/s.

 

didnt read close enough my bad

 

what about the EGR valve. if that opens while at idle i can make the motor run rough or die

 

yeah, the most common symptom of a CPS going bad is a NO START (in my experience) and a bad idle air control will cause your 4.0 to shut off at red lights (in my experience) Good Luck!

 

Didn't think they had an EGR system.

 

some jeeps had egr,some did not. bad egr sympoms are no start, surging at idle , surging on highway. block it of , use very thin sheetmetal or use shears and cut small flap out of soup can or similar, loosen egr bolts ,slide shim between gasket and valve and tighten bolts..... if this fix ,leave shim in or replace valve.

 

87-90 had EGR

91 and newer do not.

 

You could try and change the TPS. I had the same problem in my durango. If i was at a stop the RPM's would be kinda jittery then slowly get lower then shut off. Changed out the TPS at autozone and the problem was fixed.