1998CherokeeXJ

I have a 1998 Cherokee with the 4.0 and when I start it up anytime and put it in drive it feels like the engine is starving for fuel and sputters, So i put it in park and the rpms drop real low then catch back up to about 1000. But if I shut it off and restart it once i put it in park it runs fine most of the time, somtimes I have to restart it twice to get it to run right again. Any ideas what this might be? I was thinking either my fuel filter, fuel pump, or both (neither of which have been replaced that I know of and I have 133,000mi on the jeep)

xj93flexin

I have the same problem. I tried cleaning out the tb workd a little bit. I was told could be the iac or possible o2 sensor.

1998CherokeeXJ

I checked the throttle body and it looked fine, my downstream o2 sensor has been bad for about 2 months and this just started occuring so I dont think that is the cause

klump

i doubt its a fuel problem, but you'd prolly wanna check it. you can rent a fuel pressure tool from auto zone and check the pressure at idle and such. i think its suppose to be like 49psi and should hold pressure after shut off.

does it run rough RIGHT at start up or does it start okay and then taper off? and does it ONLY wanna die when you take it out of park and into drive? does it only do it at idle or does it drive okay? have you done any research at all on your problem or tried any kind of tests? you havent given much.

Radi

I'd check TPS operation...watch the output voltage while operating the throttle by hand. Key on, engine off. Any skips, dead spots or dropouts and it's done. Should be a steady voltage that rises smoothly as you open the throttle.
Also take a look at your IAC, clean it up while it's removed.

1998CherokeeXJ

It runs fine at startup. When I put it into drive and give it between a quarter and half pedal it runs the same way a carbureted engine would run if you put on full choke while it was running and proceeded to give it throttle, like it loses power and will kinda of sputter, unless you really step on the gas or i figured out today that if I feather the throttle when it starts to act it up it eventually stops occuring and runs right if that makes sense. The problem doesnt occur at idle, only when accelerating, when I come to a stop once the problem occurs the engine idles really rough and the rpms drop down to about 200 like its going to stall then it catches and they go back up to where they normally should be and it idles smooth. I asked a couple people that I know who have lost fuel pumps and they said they had similair issues

VTJeep

Maybe o2 related

tjwalker

Test your way to a solution. Start with fuel pressure.

For your vintage, you should have 49 psi, plus or minus 5 psi at idle.

If you don't have a fuel pressure gauge, many parts stores will rent you this tool.

You must eliminate this before moving onto other possibilities. It is the first thing a Technician in a shop would check if there are no check engine lights or codes.

klump

you seem pretty set that it is a fuel delivery problem. Get a gauge from autozone and check. I believe someone here said it should be around 49psi.

xj93flexin

I figured out my jeep I had same bucking problem n idle n plugd in a scan tool n its the ect code it threw. I have a short going to it. Try. CHecking that out..

1998CherokeeXJ

Thanks, I'll go to advance auto after school and see if they can rent me a fuel pressure gauge and post my results

residentg

I have a 1999, it had the same problem, ended up being the O2 sensor in the exhaust header, works fine now.

1998CherokeeXJ

Yah I've been throwing a CE for about 2 months now for the downstream o2 sensor and its galded into the cat pretty good so i was just putting of fixing it until I got a new cat. Maybe the other sensor went aswelll. Ill order my new catalytic converter tonight and install the new NGK o2 sensor I got. Any opinions on a good high-flow cat? I looked at a flowmaster one

1998CherokeeXJ

Got the codes read, only throwing a P0138 which said o2 sensor short to voltage bank 1
Sensor 2
So I got the new cat and Im going to install the new downstream 02 sensor and cat tomorrow and see if that fixes the problem

1998CherokeeXJ

disconnected the upstream o2 sensor and the issue, stopped. I guess what was happening was that the faulty o2 was sending a bad reading and possibly flooding the engine, just got a new o2 sensor today and am gonna put it in. So if anyone has this issue start by disconnecting one of the o2 sensors and see if it fixes the problem, it can potentially save you alot of money