Topic: 2.5 strange Acceleration issues

[Al-88Wrangler]

Hi everyone! This issue with my 1988 YJ 2.5 has me stumped as well as my mechanic, who has basically given up on trying to figure it out. The problem that I'm having resembles a fuel related problem. I've already replaced the fuel pump, filter, and TPS trying to fix this issue, this did noticeably smooth out the idle, but the issue still remains. Here's what happens:

When the engine is completely cold, I start up the jeep, and it will run beautiful. At that point, I can basically drive it around forever (or so it seems) without an issue - as long as I don't have to shut down the engine. If I do shut down the engine (i.e. to run into a store or get gas), that's when I seem to have the problem. After I start it back up, it will idle fine, and I can rev the motor....BUT as I start to drive down the road, it doesn't seem to want to go over 20 MPH or so - I give it gas and get nothing - as if it were starving for fuel. It acts like this for about 5 minutes, then it will smooth out, and will run fine again.

This problem has me totally baffled! The cap, rotor, wires, plugs are all relatively new, along with the Crankshaft Position Sensor. I don't really know what to look at next. My mechanic ran a diagnostic on it, but since my jeep is an 88, he says it doesn't store any codes, and the test always comes back as everything is functioning normally. He suggested that I could try to replace the MAP sensor and see what that does...

Any suggestions would be appreciated!!

Thanks,
-Al

[countryboy514]

I had an intermittent hesitation after a hot start on my 97 TJ. It was the O2 sensor! I would check the sensor voltage with a scanner. If it doesn't cycle, replace it. they are actually recommending replacing O2 sensors at tune-ups for improved gas mileage.

[Al-88Wrangler]

I had an intermittent hesitation after a hot start on my 97 TJ. It was the O2 sensor! I would check the sensor voltage with a scanner. If it doesn't cycle, replace it. they are actually recommending replacing O2 sensors at tune-ups for improved gas mileage.

You are absolutely correct!  I never came back to update this thread, but I eventually switched out the o2 sensor, and my problem did go away.  The ironic thing is that I had intended to replace the o2 sensor some time ago, because the PO, for whatever reason, cut the wires on the sensor. I bought it, but never put it in.  I would have never thought that was causing the problem.  Live and learn I guess.