91Briarwood

I wanted to adjust the timing on my 91 4.0L because I have a ping going up hills. I'm having a problem spinning the distributor. I loosened the bolt on the bottom of the distributor almost all the way and I still can't get it to spin. If anyone knows the proper way of loosening the distributor let me know, thanks

jeep19xj91

timing is non adjustable on a 4.0

91Briarwood

ahh that would explain it, thanks man

jeep19xj91

yeah it kinda sucks, i believe its all controlled through the computer

rrich

The ping - are you using the plugs called out on the undehood label or trash the parts store SOLD you.

It does make A BIG DIFFERENCE.

peep

Ping a lot or often or just once in blue moon or only under heavy load?
your ping can be carbon deposits creating hot spots, lean mixture,todays low octane gas, hot engine running temp. and/or all of the above. Run a bottle of snake oil thru the gas to clean up some possible carbon deposits.
Pull a couple plugs, light tan (good). Or dark, black, or carbon buildup (bad) try another tank full spiked with cleaner.
Are you having oil consumption issues? Do you run standard heat range plug? Champion RC9YC is a standard and moderate heat range plug for your XJ.
Stick with Regular fuel but try a brand change.
Super white and possible light metalic buildup, too much bad, too too hot, too lean a burn, run a cooler heat range plug. Run more snake oil to clean out the injectors. Beyond that check fuel pressure to try and locate cause of lean condition.
Regular oil and filter changes will clean out your engine, (regular changes).
Let us know developments.

91Briarwood

The ping only happens when going up hills or at higher rpms, and it sounded almost like an advanced timing ping, so thats why I thought my timing was off. I just replaced my spark plugs with the champions, but I have yet to try a fuel system cleaner. I noticed my fuel mileage has been going down recently, and the carbon buildup would explain that too. I'm going to try the fuel system cleaner, do you think seafoam would do the job just as well as snake oil? Because I planned on running the seafoam in my crankcase to clear up a sticky lifter, and I don't want to be running too many different additives at once.