Mrbigmover

First time poster

Has this issue been solved? I have a 01 Laredo 4.0 doing the exact same thing except sometimes instead of just cylinder #4 misfire I'll get a #1 misfire and even gotten a #6 misfire. But #4 is always there. I've changed everthing the OP has checked cylinder compression, plugs are tan, checked the spark from the coil. Changed plugs, injectors, coils, all sensors, fuel pump and filter. I can erase the CEL codes and it'll drive fine until i drive over 30 mph and then let off the throttle and let it coast. When accelerating it clears up and no miss. Checked vacuum lines for leaks. Changed wires to all injectors. Even ran new and extra ground wires and cleaned the old ones. Ive never seen such a thing.

cruiser54

I moved your post over here and gave you your own thread. More eyes will see it.

You could have carbon getting built up under the valves.

There are different ways to deal with that. I prefer getting down and dirty and using water through the throttle body.

Mrbigmover

Oh I forgot. I did that as well...lol. First ran lacquer thinner thru the system a few times then remembered the old water thru the carb (throttle body) method. No success.

Thank you for moving to be seen more

cruiser54

cool. How did you "apply" the water?

Mrbigmover

Removed the duct work covering the throttle body and sprayed directly down the bore into the intake.

cruiser54

You used a spray bottle?

I hold the RPMs at 2000 or a bit higher and pour water from a small cup for short intervals. Let it bog down a little and pick back up. Repeat until I've used 16 ounces of water minimum.

Mrbigmover

Ill try that. I probably didnt do 16 ounces and pour. I sprayed thinking i could kind of direct towards different intake paths

Jake Rainwater

Another idea if the water doesn't work. Maybe check the gaps in the spark plugs and see if they are set right.