98 TJ 4.0, manual.. After driving a few miles, the Jeep loses power momentarily, slows down a bit, but then after a second or two catches back up drives normal. The electrical does not cut completely as the radio and guages continue to work, but the engine has no power. Typically, it makes this action only once per day when the vehicle is almost to normal running temp. (It occurs within a few 100 yards each time on my way to work). This has been going on for about a month now, but the Jeep has not left me stranded yet. Out of probably 20 occurrences only once or twice did it actually shut all the way down, but the vehicle started up again immediately and normally. I first thought that it might be a fuel issue, so I changed the fuel pump assembly, which permitted the Jeep to start more easily (separate issue) but the primary problem continued. Then, I thought that it may be an electrical issue. I have driven around with an OBD Scanner, but the check engine light only flashes very quickly and the Innova 5510 has not picked up any codes. I have since started a process of elimination and changed the coil, coil wire (which was bad for a different reason), crank shaft sensor, Automatic Shutdown Relay, and Distributor pickup. The plug wires are relatively new and look good/connected well. The primary ground wires appear to be connected well. I am at a loss of what to do next. Since the problem only typically occurs once a day, I have been limited to only one change per day. I am thinking that the problem may be with the engine control computer. The connectors to the computer look good/not oxidized. Any other thoughts? Thanks.
Losing Power Momentarily
- Thread starter Ed 1998 TJ
- Start date
Mark @Wranglerfix may have input, the@ symbol notifies him. His specialty is engine management. He is a great guy.
One of the first thing to do is check power and ground connections. I also swap relays from non essential items (horn, fog lights) to essential items. ( fuel pump, injectors). You may also want to look at the wire harness behind the valve cover and around the dipstick tube bracket to see if it is worn through.
This is a method I have used looking for intermittent electrical problems when tracing very intermittent electrical problems.
I used a tool I had built was a box with 3 or 4 led lights with long wires and alligator clips or piercing probes. I could tie these lights to verify signals while I was driving. I would go through the wiring diagram and pick systems and monitor until I isolated the problem. If I was looking at the fuel system I would hook up one lead to each circuit of the relay. One for the control, one power input to relay and one power output to relay. If the condition occurred I could see if which one of these circuits went off and trace it from there. This would narrow it down. If all of these circuits looked good I would move onto ignition or pcm power until I found which circuit was causing the problem. I attached the fuel pump circuit for clarity but I would go over items that could cause the problem.
Good morning gentlemen,
Thank you for the tag and I apologize for the delay in responding.
@Ed 1998 TJ We can check your pcm in a 98 and let you know what we find. I am thinking something in the pcm needs to be resoldered.
You can call me at 866-888-7710 to discuss in further detail.
Thanks,
Mark Cantrell
Thank you for the tag and I apologize for the delay in responding.
@Ed 1998 TJ We can check your pcm in a 98 and let you know what we find. I am thinking something in the pcm needs to be resoldered.
You can call me at 866-888-7710 to discuss in further detail.
Thanks,
Mark Cantrell
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