Chasing Dragons....
Long time lurker and after 5 years I finally need help diagnosing a problem that I have not been able to fix using the search function here and my FSM. This forum is invaluable and has helped immensely in all previous DIY projects.
First, its a '96, ca. 240,000 miles, stock throughout, and new leather from Frank and heated seats (which I'll post about at some point, but they are awesome!). Over the past 5 years I've done the initial tune up (still original wires at 15!), front axle service, replaced all vacuum hoses, cleaned throttle body chasing P401, replaced all coolant hoses, new brake booster, new air intake hose (from MAF to TB), sway bar bushings, lubrication fluid changes, oil pump O-ring, rebuilt power steering pump and starter, fixed lots of leaks, replaced shocks, and a lot more.
To start I have read the following specific threads (and several dozen more, maybe even most threads relating to the 80 series technical matters over the past 5 years):
vibration/shudder on acceleration
Transmission vibes??
engine hesitation, stutter light loading
How to protect wire harness near EGR
Code P0305 (#5 misfire) and Oil in the Cylinder
Tranny misbehaving?
The description of the problem is essentialy as described in many of those threads. On acceleration from a stop, or in low gear going up a hill it feels like the transmission is kind of slipping and the vehicle shudders like driving over rumble strips which feels like its coming from the rear. Once hitting 3rd gear this stops and at speeds above 30, acceleration does not cause this. It down shifts when coming to a stop very smoothly. Reverse is also smooth. My first inclination was U-joints so I replaced the rear ones because the rearmost joint had some play in it and the vibration was coming from there. Manipulating it by hand once out of the DS it had a definite reduction in free motion with a noticeable sticking point that require force to get it to move past. The other was fine. At the same time I replaced the O2 sensors because they looked original. I had to cut the nuts off to remove them because they had rusted down to 10 mm circles. Neither fixed the problem, but I consider it good and necessary PM. I then replaced the air intake hose (amazing how flexible it is when new!) and the exhaust hangers with new rubber bushings. The first hanger was cut from the exhaust but still there. I then realized the cats were replaced with a single small one and all welded into place.
The only CEL in the past 5.5 years has been the persistent EGR flow problem. No misifires, not even O2 problems despite the front most having a thick layer of soot at its base.
After reading dozens of threads here I decided to start with ignition and wiring related items, adn then bearing or hub problems. Today I checked and replaced the spark plugs (all spark plugs had white ashy deposits evenly distributed, but no cracks and no oil), checked distributor, adjusted throttle cable, replaced fusible link, checked EFI, fuel relay, all other pertinent fuses, plugs on the transmission, re-checked U-joints, checked that tires spin without resistance and that they spin in opposite directions from one another when spinning one by hand, no 6-12 or 9-3 play in the wheels, checked the wires near the glove box, and checked the ones near the EGR pipe. The wires near the EGR still have the original heat wrap, but this seems to be more of a sticky mess that can be rubbed off very slowly rather than something that can easily be removed. I did clean the part that looked closest to the EGR pipe and there were no damaged wires. I rewrapped with 500F-proof aluminum-mesh tape and pulled it back to its connecting post and zip-tied it to it.
A test drive this evening still has the same symptoms, though maybe slightly reduced (all in my head?). The idle is at normal range and smooth. You can shift through the gears and still in low it does this. Shifting through the gears with foot on the brake is smooth without any slipping. Fluid levels are where they should be in the transmission (checked running in P), smell like new, and nice and clean looking. I do think that once the engine gets to its normal operating temp that the problem gets worse than when first starting in the morning at cold.
After all that, I drained my Transfer Case (first time since owning) and refilled. One thing that leads me to believe this might be the culprit after all the other things have been checked is that there were 6 faceted metal chunks all about 2 mm long on the end of the magnetic plug. Anything to worry about? I am used to fine deposits in cars, but not something like this. After refilling I noticed tonight that some fluid is seeping out of the speed sensor there, but quite slow (must need the 2 new O-rings), so the level must have been a little low before changing. Probably just below the seep point on the sensor. The fluid I drained did not look bad and smelled like normal gear oil. It almost looked new. Also if the truck is in neutral and I turn the drive shaft I can hear a metal "clink" sound in the TC or near there - normal? Could this be due to overgreased drive shaft? I greased until it began to expand then removed the zerk to let excess out. Even so it still throws grease onto the muffler.
To end on a good note; while checking the wiring harness today I decided to mess around with the EGR while it was off and took out the little screw holding the small pipe in, took off the little hose pipe after tapping it gently antil I could pry it off, and then began cleaning. I filled it will break cleaner, tapped it with the plastic end of a screw driver, cleaned the inside, tapped, over and over. Scraped out the nearly clogged little pipe shaft and the upper part that goes into the throttle body. Sprayed it out a few more times and then checked the diaphragm for easy movement and the arm inside it. Put it all back together and after three restarts it has not come back on..... yet.
Is there anyone in the Knoxville, Tennessee area with more experience that could diagnose this? Any reliable or trustworthy shops that have experience with the LC in this area?
So, from all that could it still be the wiring harness in need of replacement? The transfer case? Or could it still be an axle/hub related problem? All the symptoms really seem to match the main wire harness threads.
Thanks!
Long time lurker and after 5 years I finally need help diagnosing a problem that I have not been able to fix using the search function here and my FSM. This forum is invaluable and has helped immensely in all previous DIY projects.
First, its a '96, ca. 240,000 miles, stock throughout, and new leather from Frank and heated seats (which I'll post about at some point, but they are awesome!). Over the past 5 years I've done the initial tune up (still original wires at 15!), front axle service, replaced all vacuum hoses, cleaned throttle body chasing P401, replaced all coolant hoses, new brake booster, new air intake hose (from MAF to TB), sway bar bushings, lubrication fluid changes, oil pump O-ring, rebuilt power steering pump and starter, fixed lots of leaks, replaced shocks, and a lot more.
To start I have read the following specific threads (and several dozen more, maybe even most threads relating to the 80 series technical matters over the past 5 years):
vibration/shudder on acceleration
Transmission vibes??
engine hesitation, stutter light loading
How to protect wire harness near EGR
Code P0305 (#5 misfire) and Oil in the Cylinder
Tranny misbehaving?
The description of the problem is essentialy as described in many of those threads. On acceleration from a stop, or in low gear going up a hill it feels like the transmission is kind of slipping and the vehicle shudders like driving over rumble strips which feels like its coming from the rear. Once hitting 3rd gear this stops and at speeds above 30, acceleration does not cause this. It down shifts when coming to a stop very smoothly. Reverse is also smooth. My first inclination was U-joints so I replaced the rear ones because the rearmost joint had some play in it and the vibration was coming from there. Manipulating it by hand once out of the DS it had a definite reduction in free motion with a noticeable sticking point that require force to get it to move past. The other was fine. At the same time I replaced the O2 sensors because they looked original. I had to cut the nuts off to remove them because they had rusted down to 10 mm circles. Neither fixed the problem, but I consider it good and necessary PM. I then replaced the air intake hose (amazing how flexible it is when new!) and the exhaust hangers with new rubber bushings. The first hanger was cut from the exhaust but still there. I then realized the cats were replaced with a single small one and all welded into place.
The only CEL in the past 5.5 years has been the persistent EGR flow problem. No misifires, not even O2 problems despite the front most having a thick layer of soot at its base.
After reading dozens of threads here I decided to start with ignition and wiring related items, adn then bearing or hub problems. Today I checked and replaced the spark plugs (all spark plugs had white ashy deposits evenly distributed, but no cracks and no oil), checked distributor, adjusted throttle cable, replaced fusible link, checked EFI, fuel relay, all other pertinent fuses, plugs on the transmission, re-checked U-joints, checked that tires spin without resistance and that they spin in opposite directions from one another when spinning one by hand, no 6-12 or 9-3 play in the wheels, checked the wires near the glove box, and checked the ones near the EGR pipe. The wires near the EGR still have the original heat wrap, but this seems to be more of a sticky mess that can be rubbed off very slowly rather than something that can easily be removed. I did clean the part that looked closest to the EGR pipe and there were no damaged wires. I rewrapped with 500F-proof aluminum-mesh tape and pulled it back to its connecting post and zip-tied it to it.
A test drive this evening still has the same symptoms, though maybe slightly reduced (all in my head?). The idle is at normal range and smooth. You can shift through the gears and still in low it does this. Shifting through the gears with foot on the brake is smooth without any slipping. Fluid levels are where they should be in the transmission (checked running in P), smell like new, and nice and clean looking. I do think that once the engine gets to its normal operating temp that the problem gets worse than when first starting in the morning at cold.
After all that, I drained my Transfer Case (first time since owning) and refilled. One thing that leads me to believe this might be the culprit after all the other things have been checked is that there were 6 faceted metal chunks all about 2 mm long on the end of the magnetic plug. Anything to worry about? I am used to fine deposits in cars, but not something like this. After refilling I noticed tonight that some fluid is seeping out of the speed sensor there, but quite slow (must need the 2 new O-rings), so the level must have been a little low before changing. Probably just below the seep point on the sensor. The fluid I drained did not look bad and smelled like normal gear oil. It almost looked new. Also if the truck is in neutral and I turn the drive shaft I can hear a metal "clink" sound in the TC or near there - normal? Could this be due to overgreased drive shaft? I greased until it began to expand then removed the zerk to let excess out. Even so it still throws grease onto the muffler.
To end on a good note; while checking the wiring harness today I decided to mess around with the EGR while it was off and took out the little screw holding the small pipe in, took off the little hose pipe after tapping it gently antil I could pry it off, and then began cleaning. I filled it will break cleaner, tapped it with the plastic end of a screw driver, cleaned the inside, tapped, over and over. Scraped out the nearly clogged little pipe shaft and the upper part that goes into the throttle body. Sprayed it out a few more times and then checked the diaphragm for easy movement and the arm inside it. Put it all back together and after three restarts it has not come back on..... yet.
Is there anyone in the Knoxville, Tennessee area with more experience that could diagnose this? Any reliable or trustworthy shops that have experience with the LC in this area?
So, from all that could it still be the wiring harness in need of replacement? The transfer case? Or could it still be an axle/hub related problem? All the symptoms really seem to match the main wire harness threads.
Thanks!
