88 MJ, gas in oil?

So I have an 88 MJ, 4.0L, auto with gas in the oil... The motor seems to be in good shape with 115-120lbs compression, zero blow by, no puff of smoke at start up, plenty of power. When first started it idles pretty good, high idle, until it warms up. Once warm it idles like crap, really low and rough like it wants to stall. But driving it runs fine, plenty of power, smooth, no misses... Then you pull up to a stoplight and let it idle and its ruff again. I'm thinking a sensor might be causing it to run rich, to much fuel. Oh it also has new 19# ford motorsports injectors.

I replaced the O2 sensor, and also the fuel regulator and now i'm starting to look at other sensors. I need to get a good multi meter I guess to check out the sensors. Where can I find a good write up about troubleshooting this motor, I doubt the Jeep dealer will be able to help me as its to old! What sensors should I be looking at.

Thanks...

http://www.lunghd.com/On_Site_Tech.htm

look for anything renix

if the o2 sensor is new I'd suspect the coolant temperature sensor next.If thats bad your motor will stay in open loop(warm up)mode and cause your motor to run rich.

You have the correct thermostat in there right?195*.....what temp does your motor run at?
Also make sure your tps is adjusted correctly.

89xj said:

http://www.lunghd.com/On_Site_Tech.htm

look for anything renix

Click to expand...

Great site! Looks like I really need a good multi meter.

Not sure on the t-stat, I've never touched it... But it does run over 200, it'll overheat if it sits and idles. But the elec fan won't turn on by itself, if I turn the a/c on the elec fan will come on it it won't overheat. Thats next on the list of things to fix.

Well, it looks like I have a list of things to start checking.

Heres another good one. Dial Up beware-
http://f1.grp.yahoofs.com/v1/UIv6R3zn-6nWTLddNcqNWRBk2Q0xmrDVMC3RvBEFH14HYh1f0dfW-9YagvLhp5PPBcS5rTafcYhEfCcdTAz8qS9Il64URadfMA/Technical%20Archive/89JeepFI.pdf

I am wondering though, can these renix jeeps be put on a scanner to find faulty sensors so I don't have to sit and check every single one of them? I'd gladly pay an hours worth of labor at the stealership so I don't have to sit all day checking sensors.

Short answer is , NO .

a snap-on mt2500 can read live sensor data of the renix but wont give you fault codes.

damn, dealerships must have had one hell of a time working on these things. But if you can read live sensor data, I would assume if you find data that doesn't look correct you find a faulty sensor? I guess if you know what your looking at.

Anyway, I have my list made and I'm going to start going through them as soon as the weather cooperates. Winter storm warning here 4-8" of snow expected...