88cherokeepyles

1988 xj 4.0, auto. New to me in the last 4 months. Did a tuneup, etc recently.

So I load up the jeep and head up the mountain for some fun camping. Halfway up, it starts majorly lacking power. It would misfire and only go about 30-45 up a steep hill (highway grade). If I push the pedal further, it revs for a bit then really chokes up, and it doesn't catch past a certain amount. I stopped and popped the hood and there is a major loud hiss coming from intake area, and the idle is extremely rough. Like major misfire (I think), as it it lurches and seems like very few cylinders are firing, only catches 1-2 times a second (Instead of a constant firing). sounds really bad. It still drives but if you rev too hard it will not catch past (in my estimation) about 2000-3000 rpm.

We stopped in a small town, had the mechanic look into the problem, and said the hiss noise was a good indicator of air leak, then it runs too lean. He sprayed something around, found that if he sprayed where the intake gasket is, that it would change the idle, so the conclusion was that the gasket was gone bad. He wanted 300 something $ for it, plus didn't have time that day, so I drove home, looked up directions, got under there with a buddy and took off the intake and then replaced the gasket.

It took us 8 hours because we are no mechanics... To no avail. Same noise.

Now I'm at a loss, wondering what to do.

Also, looking at all these weird little hoses and stuff (tiny hoses that plug into the odd plastic device) on top of the intake near the air box, I'm fairly certain some are mis wired, but I don't know what they are called and can't find anything on line to help me figure out what is up with those and how to get them back on correctly.

Any help appreciated. sure as heck hope it isn't something in the engine.

88cherokeepyles

bumping it up a bit... anyone?

Tattookid85

I just started Having the same problem with my truck this weekend

67 GMC

Most of those are vacuum lines. If you pull them off you will hear a hiss when the jeep is running. Get a Haynes manual for starters. I've got an '87 XJ and they are some work to diagnose the issues. I had a problem with my Throttle Position Sensor. Pulled off the the big rubber hose on the intake and sprayed carb cleaner on the throttle valve. Problem fixed. It an no power and would start dying if you put the gas to it.

Good luck -this forum is great for help.

Tattookid85

Well I found out my cat was clogged, fixed my problem

88cherokeepyles

Crazy. Looked into the vacuum stuff. Found a digram, there was this plug thing that goes into the throttle body, and it had fallen out!

Put it back in, and reconnected everything according to the diagram, and the hiss is gone, and the power is mostly back. Misfire is gone..

It struggles up hills still and when it tries to accelerate fast, something in the back misses. I think fuel filter. Possible when I put sea foam in the tank it knocked loose some gross stuff at the bottom and it's clogging the filter.