zeep99xj

My 99 sport hesitates sometimes off the line. The jeep starts fine, really well actually, but from time to time i get a really bad hesitation, i have to pretty much floor it to clear it out and this often leads to a misfire. It also dies sometimes when im stopped at a light or stop sign. I changed my plugs and wires and the problem went away for a few days but now its back. I am going to replace my rear o2 sensor today that i ripped out while wheeling. I have read that the o2 sensor could cause the hesitation but i have ran without an o2 sensor for awhile before and i didnt have this problem. I do have a cel on and i got it scanned and its just for the o2 sensor so im thinking its not the distributor. A bad distributor would throw a code right? So what else should i check if the new sensor doesnt fix the problem? i really dont want to have to drop the gas tank if i dont have to because i am very busy and dont really have the time so im hoping its not the fuel filter or fuel pump. What would be a way to check the pump and filter without actually having to drop the tank?

Thanks for any help

tjwalker

1. Be sure both oxygen sensors are functional. Very important.

2. Post any codes that you get after that here for comment

3. Fuel pressure is easily verified with a fuel pressure gauge. You can rent them from many parts stores. For a 98, you should have 49 psi at idle, plus or minus 5 psi. Takes about 15 minutes to verify this. You absolutely want to test before replacing the fuel pump assembly on a hunch......

4. FINISH the tuneup with a new distributor cap and rotor. Two very important pieces of hardware for efficient secondary ignition.

5. Clean the throttle body and idle air control. They get carboned up over time and miles.

XJGirl23

Yup. Boyfriend's Cherokee had the same issue and it was the o2 sensor...the front one, I believe.

zeep99xj

It threw a p0138 code. Im going to put in a new sensor now. That is the sensor after the cat right? And i got a new cap and rotor to complete the tune up so we'll see what happens i guess

J20jeepster

Let me know haw that goes and if that sensor fixes it! Mine has the same code. It will miss now and again but not bad. Mine is already running new cap, rotor, plugs, and wires.

tampaviking

Did you check to see if any of your fuel lines were damaged while wheeling. This same thing happened to mine and it turned out to be a rotted rubber hose for the fuel pump. Wasted alot of money before I pulled the pump out. $2 fix.

Yollasho

You may want to check the tps.

It can cause some shi%%y accel, decel, and general throttle position problems.

good luck!

zukeeper

thats what I was going to say , they can almost get what seems a dead spot in them