Gas in oil & Ultra rich exhaust !!!

Ok here's as many symptoms as I can recall:


Vehicle: 89 xj, 4.0L MPI, 155K

Rough idle mainly when cold, sometimes when at operating temp.

Once warmed up however, acceleration usually strong & smooth.

Ultra rich smelling exhaust, strong odor of fuel espically when cold.

Checked: MAP, MAT and ECS.

Installed NEW: plugs, wires, cap rotor and swapped coil/module with known good.

THEN I just found, fuel in oil pan, about 3 quarts over a period of 3000 miles !

I'm thinking I've got a leaky injector or two.

I need a reality check here.... did I miss something ?

Any help appreciated :wierd:

how many miles? It sounds like a couple problems .Did you check or replace the o2 sensor? if its bad it can cause the motor to run rich. But I also think you may have a bad injector or 2.Also if you are getting gas in the oil sounds like you got some pretty bad blow by in the engine I would check compression and spark I would bet you have at least one cylinder that is low on compression. Hope its something simple but I doubt it.

Prob one or two leaky injectors that continue dribbling once you turn it off letting residual pressurized fuel to go past the rings and down into the oil pan. Normally that would cook off if you ran it long enough.

hmmm

CTS could be to blame too, worth a check with the voltmeter

I can think of these possibilities:

1. Bad O2 sensor. If you're getting only 0.0-0.2v from the signal wire even with the engine running pig rich then it's definitely bad.

2. Faulty fuel pressure regulator. Check fuel pressure at the injector rail. It should be 31psi with vacuum attached and 39psi with vacuum off the regulator.

3. Bad MAP sensor. Check the voltage from the middle signal wire with the engine idling. It should be somewhere around 2.0v. If it's much higher than that, the sensor could be faulty or there's a vacuum leak.

4. Vacuum leak. Also check tube going from MAP sensor to manifold and make sure it isn't cracked/broken.

5. Plugged cat. Even if it was OK before, the rich condition will cause the ceramic material inside the cat to break down.

155,000 miles on engine.

Thanks for all the ideas,
Right after I posted original thread I went and swapped MAP's (I have two identical xj's) no difference.

I'll check some more sensors, I didn't ckeck O2 because I thought it only comes into play when in "closed loop" mode. Engine at temp. Am I wrong on this one ?

As far as "blow by" goes, I'll run a compression check, although engine has never even burned 1/2 qt oil between changes (3000mi).

Any line on aftermarket injectors, Autozone wants $41.00 each ,direct replacement.

Thanks.

sounds alot like my 89 when i first got it. didnt have the fuel in oil issue though. the oem plastic vacum lines like to get really brittle and crack. mine had a small crack in it that i couldnt find myself, and ended up wasting 60 bucks at a repair shop to have them put a 50cent pice of hose in place which fixed the problem.

Billy Goat,
You can use 5.0 Mustang injectors. Try 5-O motorsports on E-bay or Hyperinjector. I have soem used '88 injectors you are welcome to. PM me your address if you want them. 5 of them should be good.
Tom

My Mom's friends jeep had a fuel press regulator that would leak by into the vacume supply dumping gobs of raw fuel into the first two cylinders. It started like CRAP when it was cold and then sputtered and carried on till it cleared it out. and if you stopped for more then 5 minutes it wouldn't start again even if it was warm!!

if you hold the accelerator down during cold startup, does it start better?

Was wondering what ended happeneing with billygoats prob ? Anyone know what helped ? Have a very similar prob.

pete