Root Moose
NAXJA Forum User
- Location
- ON, Canada
I swear there is something goofy encoded in the maps of the 2001 (2000 as well?) Jeeps.
First the description and symptoms. TLDR;?
Case 1:
The Jeep is towing heavy, Jeep weighs ~5000 lbs loaded, 32" tires, 4.56 gears, trailer is ~3000-3500 lbs, towing in heavy grade coastal mountains at under 1000 ft altitude. All new exhaust, high flow cats at all three locations, new fuel pump, Banks Torque Tube, etc., etc.
The Jeep will occasionally attempt to overheat when going up the hills but it's weird. It "smells" like a software fault to me.
Once while climbing at ~3200 RPM, second gear, the gauges spiked instantly to overheat and I pulled over to the side of the highway. Ambient temp was around 90ºF and humid, four lane highway across the back of Nova Scotia.
Had been climbing for several minutes (5?) and was slowing from ~65 mi/h to steady state at around 40 mi/h.
Once pulled over I let the Jeep idle for a minute and then I shut the Jeep off; waited another minute and turned it back on (no engine start) and the gauge was still pegged. Instantly turned it off again, waited less than a minute, turned it back on and the gauge was at the high side of normal like normally when pulling grades with the trailer. I restarted the Jeep and we continued the climb for another 4 minutes or so.
Case 2:
Another long pull up a similar mountain (Kelly's Mountain, NS), ambient is about 80ºF. Similar engine load conditions. Gauge is reading high normal.
Pulled off onto one of the scenic look-out sidings to take pictures... Maybe 5 minutes max. Got back in and started the Jeep (no engine start) and it is pegged to overheat. Popped the hood, waited a minute, gauge stayed where it was. Turned off the Jeep, closed the hood, started the engine and the gauge is reading high normal. Drove up the rest of the mountain (maybe three minutes) without incident.
Case 3:
Long pull around Bonne Bay, NL. This is the steepest, longest grade encountered. Similar engine/driving conditions for speed and ambient temperature. Jeep is well heat soaked after several hours of driving.
No overheat occurs, just keeps plugging up the mountain and over.
So, these overheat events... are they real? I didn't have a pyrometer with me in my boonie box (auto-x box has it), only the factory gauge available.
Is there a way to verify what is really happening, I mean reading the computer somehow?
I wish I had time to install the LM2 before our trip, that may have provided some decent hints.
Is it possible to Megasquirt these Jeeps, completely bypass the factory coding the only plug in the factory PCM on e-test day?
Am I chasing the wrong gremlin?
FWIW, cooling system appears to be fine. Newish water pump and t-stat, original 2001 radiator. Installed a transmission cooler before we left.
Maybe I should just give up and get a V8 WJ, diesel WK or a UZJ100 Land Cruiser? But I like my XJ.
First the description and symptoms. TLDR;?
Case 1:
The Jeep is towing heavy, Jeep weighs ~5000 lbs loaded, 32" tires, 4.56 gears, trailer is ~3000-3500 lbs, towing in heavy grade coastal mountains at under 1000 ft altitude. All new exhaust, high flow cats at all three locations, new fuel pump, Banks Torque Tube, etc., etc.
The Jeep will occasionally attempt to overheat when going up the hills but it's weird. It "smells" like a software fault to me.
Once while climbing at ~3200 RPM, second gear, the gauges spiked instantly to overheat and I pulled over to the side of the highway. Ambient temp was around 90ºF and humid, four lane highway across the back of Nova Scotia.
Had been climbing for several minutes (5?) and was slowing from ~65 mi/h to steady state at around 40 mi/h.
Once pulled over I let the Jeep idle for a minute and then I shut the Jeep off; waited another minute and turned it back on (no engine start) and the gauge was still pegged. Instantly turned it off again, waited less than a minute, turned it back on and the gauge was at the high side of normal like normally when pulling grades with the trailer. I restarted the Jeep and we continued the climb for another 4 minutes or so.
Case 2:
Another long pull up a similar mountain (Kelly's Mountain, NS), ambient is about 80ºF. Similar engine load conditions. Gauge is reading high normal.
Pulled off onto one of the scenic look-out sidings to take pictures... Maybe 5 minutes max. Got back in and started the Jeep (no engine start) and it is pegged to overheat. Popped the hood, waited a minute, gauge stayed where it was. Turned off the Jeep, closed the hood, started the engine and the gauge is reading high normal. Drove up the rest of the mountain (maybe three minutes) without incident.
Case 3:
Long pull around Bonne Bay, NL. This is the steepest, longest grade encountered. Similar engine/driving conditions for speed and ambient temperature. Jeep is well heat soaked after several hours of driving.
No overheat occurs, just keeps plugging up the mountain and over.
So, these overheat events... are they real? I didn't have a pyrometer with me in my boonie box (auto-x box has it), only the factory gauge available.
Is there a way to verify what is really happening, I mean reading the computer somehow?
I wish I had time to install the LM2 before our trip, that may have provided some decent hints.
Is it possible to Megasquirt these Jeeps, completely bypass the factory coding the only plug in the factory PCM on e-test day?
Am I chasing the wrong gremlin?
FWIW, cooling system appears to be fine. Newish water pump and t-stat, original 2001 radiator. Installed a transmission cooler before we left.
Maybe I should just give up and get a V8 WJ, diesel WK or a UZJ100 Land Cruiser? But I like my XJ.