1993 Jeep Cherokee RPM bottoms out while driving

BCCHARLIE

MEMBER
1993 JEEP CHEROKEE

Electrical problem
1993 Jeep Cherokee 6 cyl Two Wheel Drive Automatic

93 Jeep Cherokee w/60K plus on rebuilt motor. When driving, RPM needle gets erratic & then goes to zero & engine stalls for a second or two & then jumps back to normal. Also does this sometimes at idle while in park. Parts replaced so far include: fuel pump, fuel pump relay, auto shut off relay, distributor, ignition coil, pick-up coil. Wires have been traced from fuel pump to motor & replaced pump connector. When driving between 15 - 70 MPH engine feels like it "surges" or "jerks" before RPM's bottom out. Sometimes it runs perfect. Drove 14 miles on highway at 70 mph without a problem, then when I exited the highway, Rpm went to zero & the surging & jerking were so bad I pulled over & shut it down. Always restarts fine & sometimes will drive okay & sometimes problem starts when pulling out of the driveway. Suspected catalytic converter, but previous owner says honeycomb already removed. Ballast resistor has also been bypassed. I suspect a short or ground problem somewhere but don't know where to start checking. Any suggestions on sensors or electrical troubleshooting would be appreciated.

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Check engine light is it On or has flashed before you? If so get the computer scanned for code/s.

Lets start by checking the crankshaft position sensor-disconnect it and connect an ohmmeter across the terminals should read infinity meaning no reading-if not replace it. Also the throttle position sensor and manifold absolute pressure sensor then report back your findings this is where we start. I'll be waiting