91 XJ: idling problems

Doug did pass the time by typing:

Yep. That and carboning up #1, and helping to clog your cat.

Saving a plug could burn out your coil. Go get some Autolite plugs and pop em in.

Could also be the throttle body idle air passage.

I wish I knew how that one plug got so eroded while the rest looked great. I guess I'll replace it tomorrow. Autolite's your recommendation then? The other plugs looked great so I shouldn't have to replace them.

How many miles are on the plugs? If more than 30K, I would dump them all.

I also prefer Champion plugs, but that is just me.

Mike

Doug wrote:

Doug did pass the time by typing:

Sometimes plugs are defective from the factory. The other thing is plugs for 1 and 6 get the least amount of cooling from the water jacket. What will cause the electrodes to erode is pre-ignition/pinging and that can be caused by hot spots, carbon buildup, faulty injector. I'm betting that the sparkplug was shot and it was causing the problem.

If you replace plugs you should replace them all. They are cheap. Getting at #1 will require a swivel socket. And use a torque wrench, plugs go to 25-30 ft.lbs.

Depending on how old your rotor, cap, and wires are you should replace those too. If you need a reference here is a ref.

The plug wasn't number one, it was number two (counting from the front of the vehicle, in ascending order). This plug was the ONLY plug that was different from the rest. It was a Champion 4412 and 1/4 (at least) of the electrode was completely worn away. The other plugs are all Autolite 985's. I'm thinking the stealership had something to do with this, because I normally use Autolite 985's. I'm wondering if they might have put in a used Champion 4412 for some bizarre reason. The SUV starts, but I'll have to see if this clears up my idling problem. If not, it's on to the TPS and throttle body for some cleaning.

Thanks for the help everyone...

I know your problem now... Its MAD at you because you called it a SUV, It's a JeeP NOT an SUV .. :)

Snow...

Snow proclaimed:

Give the guy some time. I have a coworker who bought a new jeep and wouldn't even drive the thing in the rain for a month or so. Now he is complaining because he bunged up a skid plate taking a "shortcut" at too high a speed last weekend.