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Pressure washed engine bay....HELP!!!

MikeChavez

NAXJA Forum User
Location
Eatonville, WA
Just bought my first XJ about a month ago (switched over from toyotas), so yes I am a newbie! Its a '92 with 4.0L, AX15. I put 4 to 5 hundred miles on it immediately after buying it, including a full day on the trail and it ran great. My plan after that was to do some maintenance before any more driving. The rig was very dirty throughout the undercarriage and engine bay, and I thought it would be preferable to perform the maintenance minus the dirt and grime, so I decided to do some pressure washing first. I used a light duty pressure washer, cleaned the whole underside, a little bit in the engine bay, and it hasn't run right since.
At first it was ticking so loud, running so choppy, and hesitating so much that I really couldn't drive it, and a couple of times I could not get it to fire up. I immediately changed the motor oil, plugs, wires, cap, and rotor (there was a bit of moisture in the distributor cap when I pulled it off). This definitely helped. I was able to start and drive it, the tick was still there but quieter, and it was still quite rough and hesitant, especially when accelerating.
The fuel pump was very loud even when I bought the rig, so today I replaced it along with the filter, which did improve the situation. The tick is now even quieter and sometimes not there at all, and its still choppy and hesitant, just not as quite as bad.
I'm hoping to get a list of things to check. Anything that would cause problems like this, and especially things that I could have messed up in the motor bath (note that I only sprayed water from the valve cover left, not at all on the intake side). I'm lined up for a compression test tomorrow evening, which is something that I wanted to do anyway. Any help would be much appreciated.
 
sounds like you may have gotten moisture in the throttle position sensor. it doesn't take much, as they hate water more than cats do. the tick is likely just a slightly cracked header, changing the stuff you did probably just made the jeep run smoother, making the tick less pronounced.
 
sounds like you may have gotten moisture in the throttle position sensor. it doesn't take much, as they hate water more than cats do. the tick is likely just a slightly cracked header, changing the stuff you did probably just made the jeep run smoother, making the tick less pronounced.

I'm with Hellbent on this--the TPS is VERY vulnerable to moisture.
 
I'll do a thorough check of the vacuum lines tomorrow. What about the TPS? Any way to know if that's it without replacing it? Are they pricey? Thanks for the help, I'm hoping to be on the trail this weekend!
 
you could try backprobing the connections with an old style "needle" multi-meter, with the key on, move the acc linkage by hand checking for a smooth sweep in reading. any jumps, dead spots, etc. means a definite problem. or you could just remove it, and try to clean it out/dry it with electrical contact cleaner, see if it changes anything.
 
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