RedIndian2000

Hi All,

This is my first post, I've read a lot on the forums and just recently have been dead ended with ideas. The Jeep in question: 1992 XJ Laredo, 156K, 4.0, all stock.

I just started noticing a slight miss at idle that was enough to feel shudder through the Jeep. It runs fine at speed and with my foot on the gas.

In the driveway, I started the engine and pulled one plug wire at a time to find which cylinder was missing, but it didn't idle any better or worse no matter which wire I pulled. I even pulled two side by side and didn't notice much if any difference. As I went along, I also held the wires close enough to the block to get a spark from each to make sure their was ignition. The spark plugs are crusty on the tips from two bottles of Sea Foam earlier this year, and I'm going to change them tomorrow. I did clean the gaps with fine sandpaper and pop them in for now.

But, this is my first Jeep and my first inline 6 so maybe I'm missing something. I had a plug wire come loose a few months ago and it definitely stuttered and ran weird until I pulled over and found the problem. Why would it now hold a respectable idle even after pulling a plug wire? Could the crustly plugs be creating a dieseling effect?

Thanks for any input,
Adam

tjwalker

Time for a tuneup. The importance of fresh tuneup hardware cannot be overstated.

Fresh Champion copper plugs gapped to .035, new quality plug wires, distributor cap, rotor and fuel filter.

THEN see where you are at. It may or may not resolve your problem, but gotta start with this.

RedIndian2000

Thanks TJ,

I replaced the plugs and gapped them at .035". The fuel filter was the worst, I wish I'd taken a picture before I tossed it because I think it was the original one. I bought the Jeep as a one owner from an old lady so I wouldn't be surprised. It was rusted to hell and still had the rubberized undercoating on it and the bracket the same as the bottom of the Jeep.

Now the engine runs much better, but I have a feeling I'm going to have to pull the injectors soon with the rusty fuel that poured out of that filter...

Thanks for the help!

tjwalker

For your particular situation, I wouldn't hesitate to use a fuel system cleaner. BG44K is my favorite for abused systems (like yours). My second choice is Techron (by Chevron), which is widely available but not quite as strong.

BG44K is spendy and hard to find, but you should be able to order it online. Google it and be sure to try ebay; it is pretty popular there.

Did you get new plug wires, distributor cap and rotor installed yet? Your tuneup is absolutely NOT complete without these items being replaced.....always replace these tuneup items before moving onto things like fuel injectors.

Keep us updated!