renix 4.0 won't idle past 3500

[JeepcoMJ]

any ideas what could cause a renix 4.0 to not idle past 3500? it acts like that's its limiting rpm.

 

it's an 87 4.0 with auto. I've swapped ignition pack, engine computer, tranny computer, MAP, and throttle bodies still the same.

 

leaning towards bad CPS?

[Eagle]

Idle speed for the 4.0L is 650 RPM. What's this about 3500 RPM "idle"?

[Pete M]

I think he means that it won't rev higher than 3500. :D

 

Did this come on suddenly or gradually?

[Geonovast]

Bad ECU?

[HOrnbrod]

Not sure if this will help in your Renix case, but a guy over on the Strokers forum had the same problem - turned out to be a mis-indexed distributor.

 

http://www.jeepstrokers.com/forum/viewtopic.php?f=15&t=568&hilit=limited

[JeepcoMJ]

I think he means that it won't rev higher than 3500. :D

 

Did this come on suddenly or gradually?

 

yes, won't rev that far. idles at 650rpm tho.

 

new ecu made it run better.

 

Bad ECU?

 

as stated, already swapped it out. not the problem.

 

Not sure if this will help in your Renix case, but a guy over on the Strokers forum had the same problem - turned out to be a mis-indexed distributor.

 

http://www.jeepstrokers.com/forum/viewtopic.php?f=15&t=568&hilit=limited

 

thanks hornbrod...I hadn't even thought of that.

 

that's pretty likely actually, knowing who worked on it previously. just pissed I didn't notice the problem 2 years ago when I originally bought the truck (it's passed through two friends since then)

 

-Pat