I have a 89 xj ,4.0 . And yesterday it wouldn't start . Well finally I got her running she ran fan ,drove her around . Then went out started and idling way fast and exhaust manifold was fire red ,if anybody has any ideas plz help me with I'm boggled

 

Idle Im not sure about....the glowing manifold is usually a sign of burning very rich.See if you have a strong raw gas odor from your tailpipe.Also make sure theres no gas in your oil.

 

I will check that out . I have never seen an exhaust manifold get that hot . Thanks

 

yes it definitely running very rich if that's happening. Sounds like it's not entering closed loop mode like it's supposed to.

My first though is a fairly big vacuum leak - most likely the hose running to the MAP sensor (which controls Air/Fuel ratio in open loop mode). Also check the other vacuum connections for leaks as any one of them could contribute to the loss of vacuum.

Also test the MAP sensor electrical function - there are a few writeups on doing this floating around if you search

 

Yeah that's what Iam thinking too. See I took the airfilter out yesterday cause it wouldn't start and I'm thinking air vacuum line has came off but don't know where at . Thanks for info

 

Well there is definitely gas in my oil . What do I do now any ideas

 

Definately change your oil, limit your running time gas will wash down the the cylinders then youll have more problems than vacuum leak.
I just went through this but mine was 2 stuck injectors on my stroker.

 

this is a byproduct of you running very rich. Fix the problem, then change the oil asap afterwards.

Limit your driving in the meantime.

 

So the gas how did it get in there in the first place and the engine will be ok after changining oil. And u say I have a bad vacuum leak somewhere

 

fishtaco makes a good point, you may have 1 or more injectors that are stuck open, effectively just dumping raw fuel into the cylinder.

It gets into the oil when this happens and the engine is cold (gaps are biggest around pistons when the engine is cold). It seeps past the piston rings and down into the crankcase.

 

Use some carb cleaner, or an unlit propane torch along the intake, throttle body, any vacuum lines, etc. The idle will lower/ stumble when it gets sucked into the leak.

 

I will try that. Yeah it ran just fine then I parked and restarted and started idling fast liked choke is wide open

 

to check if the injectors are staying open, grab a long metal screwdriver and place it on the top of each injector with your ear on the handle. They should make a clicking sound. The one(s) that doesn't is stuck open.

 

I will try that's thanks

 

Try searching for TPS Adjustment/ Test, being you have a Renix the TPS is adjustable, also I have read that the Renix TPS, can/will do some wierd things if the power has been disconnected. Just a thought if no vacuum leaks or stuck injectors are found.