2.5, Engine Problem...

[Muspah]

Anyone have any ideas on this one?

92' Wrangler, stock (for now) has 2.5 ltr with 133k on it. Starts fine, runs fine, plenty a giddy-up. No misfire, no back fire. Great up to speed and down. However, when you reach a constant speed and keep it there(hold the peddle), the engine jumps and lurches like it is in the wrong gear. It will do this at any speed and in any gear, as long as you keep a constant speed. It seems to happen more when the engine is cold and it's even worse when the weather is cold. But as soon as you give it a little gas it stops.

Any clue as to what I should be looking for?

Thanks in advance, I have a lot of things on the to-do list and will keep you all posted on the progress(if I find the money)

[Joker®]

IMHO,

First, check for an air intake leak between the bottom of the throttle body and the intake manifold/block. Use an unlit propane torch and move it along the outside of the intake system. You'll get a RPM change if you have a leak.

Second, check the fuel pressure at the fuel rail, it should be 31 psi with the vacuum line (from the fuel pressure regulator) attached, 39 psi with the vacuum line detached.

Let us know what you find out.

[Muspah]

Thanks Joker-

I will give it a look when the weather breaks. Cold rain in DE today, no garage to work in...

If anyone else has an idea, I'm open to try it.

[Muspah]

Hey Joker-

Tested for air leak at throttle body, NO LEAKS found.

Pressure at fuel rail is 30-31psi. Needle jumps around 30 during idle, but holds a solid 31 with a little accel. I will put a new fuel filter on once a little snow melts out here :shock:

I will let you know if anything changes.


Muspah

[HummerzDad]

Hey Muspah, sounds like what mine was doing last week and it ultimately was the oxygen sensor....... I ended up replacing the fuel filter befor I got it on a puter and found out what it was.

Hope this helps!!!!!!!

Good Luck!!!!!!

[Muspah]

Thanks Hummer-

I gave the O2 sensor a thought but I'm not getting the check code for O2 so I just blew off that idea. I'm not really having any trouble driving, it's just a PITA somtimes.

Thanks again

Muspah