Okay. I'm gonna try looking for answers here one last time before I head to a shop.
CF Veteran
Joined: Jan 2015
Posts: 1,381
Likes: 3
From: Southern Maryland
Year: 1991
Model: Cherokee
Engine: 1999 4.0L
Sounds like the coil to me, it will cause sputter and backfire when it starts to die. A simple inline spark tester will let you watch the coil-to-distributor output and see if spark starts dying off at higher RPMs.
Could also be battery or alternator. Jeep runs like crap when voltage is low. You can take them both in for testing
Could also be battery or alternator. Jeep runs like crap when voltage is low. You can take them both in for testing
Thread Starter
Junior Member
Joined: Jul 2012
Posts: 43
Likes: 0
Year: 1992
Model: Cherokee
Engine: 4.0l I6
Sounds like the coil to me, it will cause sputter and backfire when it starts to die. A simple inline spark tester will let you watch the coil-to-distributor output and see if spark starts dying off at higher RPMs.
Could also be battery or alternator. Jeep runs like crap when voltage is low. You can take them both in for testing
Could also be battery or alternator. Jeep runs like crap when voltage is low. You can take them both in for testing
I just opened up the entire wiring harness and the only new thing I found is the single wire from the oil sending unit by the dizzy had its rubber melted off where it runs with the starter wire. I'm assuming when I shorted the starter it melted the rubber on that oil sender wire. Can't see that causing the problems though.
Seasoned Member
Joined: Aug 2015
Posts: 404
Likes: 18
From: New Jersey
Year: 2000
Model: Cherokee
Engine: 4.0L
Have you checked for vacuum leaks yet?? They cause all kinds of nasty problems, try sparying carb/brake cleaner around the vacuum lines with it running. If the engine revs, you found your leak.
CF Veteran
Joined: Sep 2012
Posts: 1,623
Likes: 13
From: In a large sandbox
Year: 1998
Engine: 4.0
Replaced the coil, also saw spark from all 6 wires. Voltmeter put on the battery terminals while running shows it hop around from high 13s to mid 14s as the idle flops around and grumbles.
I just opened up the entire wiring harness and the only new thing I found is the single wire from the oil sending unit by the dizzy had its rubber melted off where it runs with the starter wire. I'm assuming when I shorted the starter it melted the rubber on that oil sender wire. Can't see that causing the problems though.
I just opened up the entire wiring harness and the only new thing I found is the single wire from the oil sending unit by the dizzy had its rubber melted off where it runs with the starter wire. I'm assuming when I shorted the starter it melted the rubber on that oil sender wire. Can't see that causing the problems though.
Newbie
Joined: May 2018
Posts: 3
Likes: 0
Model: Cherokee (XJ)
It's been 4 weeks now and I'm done. I'm either gonna take it to a shop or put a carb on it. Here's the break down...
92 Cherokee Laredo 4.0.
History...
Fully rebuilt the engine two months ago so the engine itself is fine.
One month ago I noticed a coolant leak from the bellhousing.
Removed tranny and saw bad freeze plug.
Replaced freeze plug, replaced tranny.
Noticed pinhole fuel leak in hose between fuel pump and fuel filter. Replaced hose and filter.
Problem...
Starts, idles, will NOT rev past 2k rpms. Just spits and pops and gasps.
What I think caused it...
I DID forget to unhook the battery when I started to remove the tranny and the starter arced against the frame.
What I did...
I have replaced the ECU, the crank position sensor, the o2 sensor, the ignition coil, the cap and rotor.
Getting spark out of all six wires.
Fuel pressure test shows 36 to 40 psi at all times.
I tested the TPS and it showed a volt range of .060 to .200. It is supposed to be .200 to 3.80ish.
Bought an Autozone TPS and it read the exact same voltages so I took it back.
Bought an O'Reilly TPS and it read the exact same voltages so I took it back.
While examining the wire harness a frayed wire to the TPS grounded against the manifold and caused the fuel pump to cycle.
I then fixed the frayed wire and now the (original) TPS reads perfect voltages. (.300 to 3.80ish).
Problem as of now...
Will NOT stay running when cold. I have to start it about 15 times before it holds a TERRIBLE clunky idle.
The idle gets better and better until it warms up and idles just fine, but it WILL NOT REV PAST IDLE.
It just clunks and pops out the intake and out the exhaust and acts like it is missing terribly but will NOT rev past 1000k to 1500k.
Stinks to high heaven. Plugs are all fouled.
Removed muffler and can see bright glowing red inside the catalytic converter.
What. In the hell. Do I do now? Please, ANY suggestions whatsoever I will try them all.
Thank you.
92 Cherokee Laredo 4.0.
History...
Fully rebuilt the engine two months ago so the engine itself is fine.
One month ago I noticed a coolant leak from the bellhousing.
Removed tranny and saw bad freeze plug.
Replaced freeze plug, replaced tranny.
Noticed pinhole fuel leak in hose between fuel pump and fuel filter. Replaced hose and filter.
Problem...
Starts, idles, will NOT rev past 2k rpms. Just spits and pops and gasps.
What I think caused it...
I DID forget to unhook the battery when I started to remove the tranny and the starter arced against the frame.
What I did...
I have replaced the ECU, the crank position sensor, the o2 sensor, the ignition coil, the cap and rotor.
Getting spark out of all six wires.
Fuel pressure test shows 36 to 40 psi at all times.
I tested the TPS and it showed a volt range of .060 to .200. It is supposed to be .200 to 3.80ish.
Bought an Autozone TPS and it read the exact same voltages so I took it back.
Bought an O'Reilly TPS and it read the exact same voltages so I took it back.
While examining the wire harness a frayed wire to the TPS grounded against the manifold and caused the fuel pump to cycle.
I then fixed the frayed wire and now the (original) TPS reads perfect voltages. (.300 to 3.80ish).
Problem as of now...
Will NOT stay running when cold. I have to start it about 15 times before it holds a TERRIBLE clunky idle.
The idle gets better and better until it warms up and idles just fine, but it WILL NOT REV PAST IDLE.
It just clunks and pops out the intake and out the exhaust and acts like it is missing terribly but will NOT rev past 1000k to 1500k.
Stinks to high heaven. Plugs are all fouled.
Removed muffler and can see bright glowing red inside the catalytic converter.
What. In the hell. Do I do now? Please, ANY suggestions whatsoever I will try them all.
Thank you.
Newbie
Joined: May 2018
Posts: 3
Likes: 0
Model: Cherokee (XJ)
It's been 4 weeks now and I'm done. I'm either gonna take it to a shop or put a carb on it. Here's the break down...
92 Cherokee Laredo 4.0.
History...
Fully rebuilt the engine two months ago so the engine itself is fine.
One month ago I noticed a coolant leak from the bellhousing.
Removed tranny and saw bad freeze plug.
Replaced freeze plug, replaced tranny.
Noticed pinhole fuel leak in hose between fuel pump and fuel filter. Replaced hose and filter.
Problem...
Starts, idles, will NOT rev past 2k rpms. Just spits and pops and gasps.
What I think caused it...
I DID forget to unhook the battery when I started to remove the tranny and the starter arced against the frame.
What I did...
I have replaced the ECU, the crank position sensor, the o2 sensor, the ignition coil, the cap and rotor.
Getting spark out of all six wires.
Fuel pressure test shows 36 to 40 psi at all times.
I tested the TPS and it showed a volt range of .060 to .200. It is supposed to be .200 to 3.80ish.
Bought an Autozone TPS and it read the exact same voltages so I took it back.
Bought an O'Reilly TPS and it read the exact same voltages so I took it back.
While examining the wire harness a frayed wire to the TPS grounded against the manifold and caused the fuel pump to cycle.
I then fixed the frayed wire and now the (original) TPS reads perfect voltages. (.300 to 3.80ish).
Problem as of now...
Will NOT stay running when cold. I have to start it about 15 times before it holds a TERRIBLE clunky idle.
The idle gets better and better until it warms up and idles just fine, but it WILL NOT REV PAST IDLE.
It just clunks and pops out the intake and out the exhaust and acts like it is missing terribly but will NOT rev past 1000k to 1500k.
Stinks to high heaven. Plugs are all fouled.
Removed muffler and can see bright glowing red inside the catalytic converter.
What. In the hell. Do I do now? Please, ANY suggestions whatsoever I will try them all.
Thank you.
92 Cherokee Laredo 4.0.
History...
Fully rebuilt the engine two months ago so the engine itself is fine.
One month ago I noticed a coolant leak from the bellhousing.
Removed tranny and saw bad freeze plug.
Replaced freeze plug, replaced tranny.
Noticed pinhole fuel leak in hose between fuel pump and fuel filter. Replaced hose and filter.
Problem...
Starts, idles, will NOT rev past 2k rpms. Just spits and pops and gasps.
What I think caused it...
I DID forget to unhook the battery when I started to remove the tranny and the starter arced against the frame.
What I did...
I have replaced the ECU, the crank position sensor, the o2 sensor, the ignition coil, the cap and rotor.
Getting spark out of all six wires.
Fuel pressure test shows 36 to 40 psi at all times.
I tested the TPS and it showed a volt range of .060 to .200. It is supposed to be .200 to 3.80ish.
Bought an Autozone TPS and it read the exact same voltages so I took it back.
Bought an O'Reilly TPS and it read the exact same voltages so I took it back.
While examining the wire harness a frayed wire to the TPS grounded against the manifold and caused the fuel pump to cycle.
I then fixed the frayed wire and now the (original) TPS reads perfect voltages. (.300 to 3.80ish).
Problem as of now...
Will NOT stay running when cold. I have to start it about 15 times before it holds a TERRIBLE clunky idle.
The idle gets better and better until it warms up and idles just fine, but it WILL NOT REV PAST IDLE.
It just clunks and pops out the intake and out the exhaust and acts like it is missing terribly but will NOT rev past 1000k to 1500k.
Stinks to high heaven. Plugs are all fouled.
Removed muffler and can see bright glowing red inside the catalytic converter.
What. In the hell. Do I do now? Please, ANY suggestions whatsoever I will try them all.
Thank you.
