1996 5.2L Engine fouling plugs

[WyoXJ]

I am thinking about buying a friend of mines ZJ if I can get it to run right again. It has a couple of motor mods, accel coil and a cold air. He changed the plugs and wires on it, ran it for a week and started fouling plugs. Idle's goes up and down, and when you step into it hard it starts back firing and running like crap. I changed the upstream O2 sensor, and cleaned the IAC. Anyone have any other ideas? Thanks

[4.3LXJ]

What kind of fowling. What color are the plugs

[WyoXJ]

Black and have a wet look to them. Am wondering if we might have a bad plenum gasket. Thanks for your help

[4.3LXJ]

Check the fuel pressure. Regulator might be stuck

[cantab27]

Black and have a wet look to them. Am wondering if we might have a bad plenum gasket. Thanks for your help

bigjim350 be the man to ask........


Is it a magnum motor? Post anothe pic of engine. The plenum on the magnum motors is known to leak. The best way to check is to take off the throtle body and look into the intake and see if you can see any oil puddling in there. The bottom gasket on those intakes is not a if, but when type thing. And will cause bad gas mileage. This might help ya.
http://www.hughesengines.com/Index/p...2&partid=26190
__________________

[WyoXJ]

I double checked the spark plug gap and found that I had to open them up a little, also used some parts cleaner on them. The idle seemed to smooth out. I also looked into the plenum it looked like there there was a little oil but not puddles of it. It is a magnum motor.

[WyoXJ]

Check the fuel pressure. Regulator might be stuck

Fuel pressure is 46psi when the key is turned on and when its running it is between 46psi to 50psi.

[4.3LXJ]

How much is it supposed to be?

[WyoXJ]

49psi plus or minus 5 psi. pulled the dist cap off and looked at the rotor it had some carbon on it. Cleaned it off took for a short drive but still missing and back firing when you step into it.

[4.3LXJ]

Any CEL? How long since the O2 sensor was changed?

[WyoXJ]

Well I got back to the ZJ today. Changed out the cap and rotor. Also swapped out the sensor in the dist. It was out of the parts zj but thought I could see if helped. still have the random misfire codes and a #8 is wet when I pulled it out. I changed the first O2 sensor on the pipe awhile back. Guess I could change the second one out to. Have been searching on the web for other things to try to clear this up, one of the things I found was to change the computer. Don't have any idea if that will help or not but might be next step.