Moved and now my jeep pings...

You have already fixed the problem. There are fuel quality and additive differences from state to state or region to region. There isn't anything that you can adjust, but if everything on TJ is working correctly, it will eventually learn to run on the cheaper gas.

I wouldn't do that. If you can hear the ping, imagine taking a hammer and whacking the tops of your pistons on each upstroke. That is what ping is doing, and no good comes from it.

Bottom line: if TJ likes mid-grade, feed her mid-grade.

Jerry

Are you at a differerent altitude?

Are you buying the same brand gas?

Check with your brand gasoline to find the additives it uses in each state.

What part of Texas? Some parts sell 86 octane rather than 87 AIR. I think some parts also use the oxygenated fuel (seems to me I saw that in Dallas/FW last time I was down there in December) but There I'm not sure. I know my old 88 4.0 sure does dislike the oxygenated crap. You might also try a different brand or station for your gas.

Or it might be something as simple as blowing the carbon out - a 50 mile run dow I20 at 70-80 mph should do it (or a can of water thru the intake - SLOWLY!

Thank you for the reply, When you say "blowing the carbon out" what do you mean? I am in Austin now, I did notice some places have 86. but I am pretty sure we have 87 here in town... Also, in CA they used Oxygenated fuel (if i remember right, they also have MTBE) and now that I am in Austin, i dont think any of those are in there...

-Kurt

But its more expensive and I'm a tight wad! :) j/k.. actually in the TJ manual it actually states NOT to use Midgrade or anything higher then 87... So i was concerned...

Thank you for the replys! At first i figured it was a brand problem so I have tried Exxon, Chev. Valero and Diamond Shamrock (which are one and the same) and those are what I use to get in Ca.. Also, i am at 900 ft elev here in Texas and in CA I was at about 300 ft.. so not much of an elev difference...

The midgrade fuels or premium fuels won't damage anything. They just cost more. Also, you may want to try a different gas station. Avoid the Holiday, Clark and C-store type places, as their gas is sometimes not as good, even though the octane rating is the same. Also , decarboning the engine like someone else mentioned, may cure your problem.

Chris

The easiest way is to just run it up I35 to Temple and back. I'm just thinking that if you haven't had it out on the road at sustained high speed and full temp for a while the cylinders will load up.

The other way is to run about a quart of water (some suggest ATF, but that makes a smoke cloud you have to see to believe) and run it thru the intake. Get the engine up to temp, pull the air intake hose off and SLOWLY dribble the water in. Keep hold of the accelerator pully to keep it from dying, but don't go wild. You don't want it to go in fast enough to hydrolock the engine. Some say to use a good spray bottle and spray it just fast enough to make the engine stumble a little. That will scour any carbon out of the chamber that could be causing pre-igniton. I have a little trouble with my MJ when I get down there but I think most of that is the CPS I have - the dealer in Colorado only kept the high altitude version which advances the timing by what looks to be about 5 degrees or so. Texaco gas is also pretty good, but I avoid Fina most places in Texas other than near the refinery.

Part of the problem could be the very recent downward drastic movement in what passes for quality in gasoline brews. All the oil companies out here [Kalifornia] claim that the new ethanol blends are superior yada yada yada. A couple also claim that adding minor amounts of ethanol to gasoline stock will improve the octane rating by a few points. Perhaps I've become too cynical but to me that tells me that they are now using even crappier base stocks with the ethanol, as there is no monetary advantage for them to exceed the pump rating.

With a 4.0 I have always had an extremely light ping in town, typically at transmission shift points. Easily gotten rid of by moving up from 87 to 89 or just buying the 87 gas in Nevada or Oregon rather than California.

Since the new ethanol blends have infested the local gas stations, this no longer works. I get moderate ping under city traffic conditions and it will only go away if I use 89 rather than 87. Haven't had a chance to try Nevada grade 87 yet.

Blowing the carbon out is generally done with an "Italian Tune-up" named after old Alfa and similar engines that really did not like being trundled around in town. Take the vehicle out of town and floorboard it up thru the gears a few times.