Getting to my wits end chasing a rough idle, limited power on my TJ.
This was a desert rescue. It had sat in the elements with a disassembled transmission in the back for 15 years.
After rescuing it a year ago, my son and law and I have been working to get it restored.
We unstuck the seized motor. New belt. New fluids. Rebuilt transmission, TC and t-case. New tires.
Long story short, we got it up and running, but it was rough. This, after fixing various leaks in the intake (verified via smoke test) and confirming air, spark, compression, fuel, etc). Once I got it running, although rough, I stumbled to the gas station, gave it the old Italian tune-up, rev’d a few times to redline and from there it ran great. I suspect it had a stuck lifter that decided to join the party.
When I say it ran great, it ran great. Very smooth, responsive, full power, and quiet.
After putting 25 miles on it around town, we took it on a 3/10 trail to the top of 4 Peaks, just east of Phoenix. It ran great going up and down. This is about a 5 hour round-trip forest road experience.
On the way home it blew a head gasket. Original owner said it had overheated, but it must’ve been a pin sized hole since it didn’t overheat until after 5 hard hours of driving.
Mind you, I’m not a believer in throwing the parts cannon at something, but it’s not generating any errors, and we are going part by part, function hy function through the restoration process. My son and law and I have gone through this Jeep step by step and can’t seem to figure out the issue.
This is what we’ve done so far:
New head gasket. Carefully scraped off old gasket with plastic razor. Purchased and installed new head, at recommendation of trusted friend who has worked at a machine shop for 30 years. Went with the blue felpro gasket. New head studs, torqued in proper sequence, with increasing ft/lb per online specs. Note, 2 of the new, never used head bolts broke during the install. Had to replace both. New valve cover, intake and exhaust gaskets. All bolts torqued to spec.
Compression tests great across all cylinders. 165-175ish.
Replaced throttle body. Air was leaking through the swivel. Tried the gasket hack but that didn’t last. Ended up replacing the throttle body, and all 3 sensors that came with it.
Replaced the vacuum connector on the brake booster. After this, no more smoke test leaks.
New fan, fan clutch, water pump, gasket, thermostat, radiator hoses, rad cap, etc. 15 years ago it had overheated, so I replaced them all. Ran compression test on cooling system. No leaks.
New spark plugs, lightning cables, distributor cap, distributor rotor, distributor coil, CPS, etc. Have confirmed lightning on each spark, and in correct firing order.
New injectors. New injector wiring harnesses.
New vacuum lines to valve cover.
Was still running rough, so used computer to disable fuel injector, one at a time. Got to #6, and no change. Odd. Have spark, compression and can feel the injector buzzing.
Cleaned fuel rail and #6. Verified fuel pressure.
Dropped and cleaned out tank and cleared out lines. New fuel pump.
On my most recent rough test drive, it finally threw a code for Camshaft Position Sensor and Crankshaft position sensor. Replaced both sensors. Had to slightly drop the transmission to get one of them out. Code went away. Still runs very rough.
If it’s been sitting, I can get it to fire up. It will progressively get worse. So much so, that on a test drive, it will eventually stall at idle.
It’s a early 1999 Wrangler TJ 4.0 Automatic. ODBII doesn’t show any issues with misfires.
What are we missing?
Video of live codes:
https://share.icloud.com/photos/07bXkP9WNGCCRn_G1n9WPEkqg
Video of it running rough. Sounds like is has a cam, but it doesn’t:
https://share.icloud.com/photos/056yGmdFZcmVEvQiVbpvTweew
This was a desert rescue. It had sat in the elements with a disassembled transmission in the back for 15 years.
After rescuing it a year ago, my son and law and I have been working to get it restored.
We unstuck the seized motor. New belt. New fluids. Rebuilt transmission, TC and t-case. New tires.
Long story short, we got it up and running, but it was rough. This, after fixing various leaks in the intake (verified via smoke test) and confirming air, spark, compression, fuel, etc). Once I got it running, although rough, I stumbled to the gas station, gave it the old Italian tune-up, rev’d a few times to redline and from there it ran great. I suspect it had a stuck lifter that decided to join the party.
When I say it ran great, it ran great. Very smooth, responsive, full power, and quiet.
After putting 25 miles on it around town, we took it on a 3/10 trail to the top of 4 Peaks, just east of Phoenix. It ran great going up and down. This is about a 5 hour round-trip forest road experience.
On the way home it blew a head gasket. Original owner said it had overheated, but it must’ve been a pin sized hole since it didn’t overheat until after 5 hard hours of driving.
Mind you, I’m not a believer in throwing the parts cannon at something, but it’s not generating any errors, and we are going part by part, function hy function through the restoration process. My son and law and I have gone through this Jeep step by step and can’t seem to figure out the issue.
This is what we’ve done so far:
New head gasket. Carefully scraped off old gasket with plastic razor. Purchased and installed new head, at recommendation of trusted friend who has worked at a machine shop for 30 years. Went with the blue felpro gasket. New head studs, torqued in proper sequence, with increasing ft/lb per online specs. Note, 2 of the new, never used head bolts broke during the install. Had to replace both. New valve cover, intake and exhaust gaskets. All bolts torqued to spec.
Compression tests great across all cylinders. 165-175ish.
Replaced throttle body. Air was leaking through the swivel. Tried the gasket hack but that didn’t last. Ended up replacing the throttle body, and all 3 sensors that came with it.
Replaced the vacuum connector on the brake booster. After this, no more smoke test leaks.
New fan, fan clutch, water pump, gasket, thermostat, radiator hoses, rad cap, etc. 15 years ago it had overheated, so I replaced them all. Ran compression test on cooling system. No leaks.
New spark plugs, lightning cables, distributor cap, distributor rotor, distributor coil, CPS, etc. Have confirmed lightning on each spark, and in correct firing order.
New injectors. New injector wiring harnesses.
New vacuum lines to valve cover.
Was still running rough, so used computer to disable fuel injector, one at a time. Got to #6, and no change. Odd. Have spark, compression and can feel the injector buzzing.
Cleaned fuel rail and #6. Verified fuel pressure.
Dropped and cleaned out tank and cleared out lines. New fuel pump.
On my most recent rough test drive, it finally threw a code for Camshaft Position Sensor and Crankshaft position sensor. Replaced both sensors. Had to slightly drop the transmission to get one of them out. Code went away. Still runs very rough.
If it’s been sitting, I can get it to fire up. It will progressively get worse. So much so, that on a test drive, it will eventually stall at idle.
It’s a early 1999 Wrangler TJ 4.0 Automatic. ODBII doesn’t show any issues with misfires.
What are we missing?
Video of live codes:
https://share.icloud.com/photos/07bXkP9WNGCCRn_G1n9WPEkqg
Video of it running rough. Sounds like is has a cam, but it doesn’t:
https://share.icloud.com/photos/056yGmdFZcmVEvQiVbpvTweew
