Armadillo
NAXJA Forum User
- Location
- Mid Missouri
I have been a lurker on this forum for years now and I decided to make a post because I have not run across a thread that outlines my specific problem. Sorry, this is a long post but I'm trying to give as much detail as I can because I am stumped.
Two weeks ago or so my Jeep (1990 4.0 AW4 NP231) would buck exactly twice shortly after I got it on the road I figured it was a misfire when it was cold or something but nothing serious but since I had to drive it 200 miles to Iowa the next week. I checked the usual suspects like plugs, wires, etc. Everything checked out but I did have a small vacuum leak that caused it to idle high.
After about 45 minutes of being on the road to Iowa, the Jeep started bucking non-stop if I was on the gas but very lightly if I let off the gas. I am defining bucking as if you are in a Jon boat and you hit a log underwater, the RPMs didn't change either. I slowly drove to a parts store thinking the vacuum leak was the culprit and somehow causing me all this trouble and dumping oil on my filter. I put a small cone filter in the front hole where the oil was coming from in order to make it home. No problems for about an hour until about 1/4 mile from our shop it starts doing it again. I park it and it won't go into reverse unless there is backward momentum. I let it sit overnight and reverse worked again in the morning. I ordered a new valve cover gasket and vacuum harnesses and replace them along with refreshing my grounds and clean about every sensor in the engine bay.
On my way back to Missouri the Jeep is running great for about 2 hours (longer than before) the Jeep bucks twice and kicks itself out of gear and makes a loud whining and grinding sound so I put in neutral, come to a stop, shut it off and sit for a second. I checked the TV cable and Trans fluid and both are fine. I restart it and try to shift in gear and it goes like nothing is wrong. Fast forward another hour and it bucks out of gear again but this time the restart trick does not work and it wont go in gear. As I sit there and contemplate how it would cost me more than the jeep is worth to get a tow 100 miles, I got the idea of pushing it to a patch of mud and seeing if 4x4 works just to see. 4hi did nothing but 4lo kicked right in and I got it going about 3mph and switched it back to 2hi and drove 90 miles no problem.... and it happened again. I did a similar procedure to my last breakdown but I did it on pavement( I know, I know never engage 4wd on pavement) I made sure that the wheels were straight and I didn't turn. Only 4lo worked to get me moving and then I switched to 2hi, made sure the front axle disengaged and kept going but the front end popped but the axle was disengaged. The odd part was that the transfer case seemed to be stuck in low range like it was in 4lo but it was in 2wd. I tried to reverse out like you sometimes have to do in 4wd but that didn't help and it runs through 3 gears before I get to 20mph, doesn't go into overdrive and runs about 3k RPM. I didn't push it to redline because I wanted to get home in one piece.
I get it home, jack it up, and check driveline U joints for binding and they check out, no play in the rear driveline when I twist it by hand, I adjusted the TPS to the correct range, clean and adjust the NSS, check the TCU fuse under the dash (its fine), adjust the transmission shift linkage (for some reason the shifter would not go into the 1-2 range and at points it would not go into park). I took it for a drive to see if any of it worked and nothing was better. I took the TCU fuse out and tried to manually shift it but that didn't help.
That is where I sit. All that has pointed me to either something with my T-case, shift solenoids, or Torque converter. The problem is I don't know how to test the shift solenoids. If anyone has any ideas please help. I don't have the money to throw parts at it until it is fixed.
Two weeks ago or so my Jeep (1990 4.0 AW4 NP231) would buck exactly twice shortly after I got it on the road I figured it was a misfire when it was cold or something but nothing serious but since I had to drive it 200 miles to Iowa the next week. I checked the usual suspects like plugs, wires, etc. Everything checked out but I did have a small vacuum leak that caused it to idle high.
After about 45 minutes of being on the road to Iowa, the Jeep started bucking non-stop if I was on the gas but very lightly if I let off the gas. I am defining bucking as if you are in a Jon boat and you hit a log underwater, the RPMs didn't change either. I slowly drove to a parts store thinking the vacuum leak was the culprit and somehow causing me all this trouble and dumping oil on my filter. I put a small cone filter in the front hole where the oil was coming from in order to make it home. No problems for about an hour until about 1/4 mile from our shop it starts doing it again. I park it and it won't go into reverse unless there is backward momentum. I let it sit overnight and reverse worked again in the morning. I ordered a new valve cover gasket and vacuum harnesses and replace them along with refreshing my grounds and clean about every sensor in the engine bay.
On my way back to Missouri the Jeep is running great for about 2 hours (longer than before) the Jeep bucks twice and kicks itself out of gear and makes a loud whining and grinding sound so I put in neutral, come to a stop, shut it off and sit for a second. I checked the TV cable and Trans fluid and both are fine. I restart it and try to shift in gear and it goes like nothing is wrong. Fast forward another hour and it bucks out of gear again but this time the restart trick does not work and it wont go in gear. As I sit there and contemplate how it would cost me more than the jeep is worth to get a tow 100 miles, I got the idea of pushing it to a patch of mud and seeing if 4x4 works just to see. 4hi did nothing but 4lo kicked right in and I got it going about 3mph and switched it back to 2hi and drove 90 miles no problem.... and it happened again. I did a similar procedure to my last breakdown but I did it on pavement( I know, I know never engage 4wd on pavement) I made sure that the wheels were straight and I didn't turn. Only 4lo worked to get me moving and then I switched to 2hi, made sure the front axle disengaged and kept going but the front end popped but the axle was disengaged. The odd part was that the transfer case seemed to be stuck in low range like it was in 4lo but it was in 2wd. I tried to reverse out like you sometimes have to do in 4wd but that didn't help and it runs through 3 gears before I get to 20mph, doesn't go into overdrive and runs about 3k RPM. I didn't push it to redline because I wanted to get home in one piece.
I get it home, jack it up, and check driveline U joints for binding and they check out, no play in the rear driveline when I twist it by hand, I adjusted the TPS to the correct range, clean and adjust the NSS, check the TCU fuse under the dash (its fine), adjust the transmission shift linkage (for some reason the shifter would not go into the 1-2 range and at points it would not go into park). I took it for a drive to see if any of it worked and nothing was better. I took the TCU fuse out and tried to manually shift it but that didn't help.
That is where I sit. All that has pointed me to either something with my T-case, shift solenoids, or Torque converter. The problem is I don't know how to test the shift solenoids. If anyone has any ideas please help. I don't have the money to throw parts at it until it is fixed.
