My wife has a 2002 Jeep Liberty with the 3.7 and an auto trans. It's got 122k trouble free miles. Recently it's had an issue that's had me at a loss. The hard part is, my wife is giving me the problem description, but I can't replicate it, and neither can our mechanic. Here's the issue:
She first noticed that when at a stop sign or stop light, her jeep would surge a bit. The first time it happened, she thought someone had tapped her from behind. The same day, she was driving home from work on the highway, and said that her engine was revving higher than it should, and it felt like the car was working harder to attain highway speed. She pulled over because the engine was revving, put it in park, and the engine continued to rev with her foot off the gas, and the car in park. She shut it off and called me. I drove out, turned the truck back on and everything was perfect. Had it towed to our mechanic friend, and he couldn't replicate it either. I had him change the fluid and filter in the transmision. He noticed a miss at idle, and recommended changing the plugs, air filter, and said the battery was on its way out too. When I got the truck back I replaced battery, plugs, and airfilter per his suggestion. When I was changing the plugs I noticed the two hoses attached to the sides box over the throttle body were cracked causing a likely vacuum leak. I replaced these hoses, and the miss went away.
The mechanic ran OBD2 diagnostics on the whole vehicle and gave it a clean bill of health. Everything's been fine for the past two weeks. Yesterday she called me and said her jeep just seemed to be working harder on the highway again. She pulled over, power-cycled the engine, waited a few minutes and drove it home.
So there's only a few things that I can think of that woulc cause such a cryptic issue:
First, some unseen vacuum leak somewhere which is causing running issues
or
The lockup in the torque conerter. I'm thinking the converter might not be locking all the time on the highway causing more slip and more revs, and not unlocking correctly at a stop causing the surging.
Has anyone else every experienced anything like this? I can't seem to replicate the problem. Are there any electronics or sensors that could fail and cause this issue? Is the converter electronically locking?
Honestly I'm at a loss. I hope this isn't a sign of a failing auto trans. My wife is a very conservative driver, and never beats on the vechicle at all.
Sorry for the novel, and thanks in advance,
-Matt
She first noticed that when at a stop sign or stop light, her jeep would surge a bit. The first time it happened, she thought someone had tapped her from behind. The same day, she was driving home from work on the highway, and said that her engine was revving higher than it should, and it felt like the car was working harder to attain highway speed. She pulled over because the engine was revving, put it in park, and the engine continued to rev with her foot off the gas, and the car in park. She shut it off and called me. I drove out, turned the truck back on and everything was perfect. Had it towed to our mechanic friend, and he couldn't replicate it either. I had him change the fluid and filter in the transmision. He noticed a miss at idle, and recommended changing the plugs, air filter, and said the battery was on its way out too. When I got the truck back I replaced battery, plugs, and airfilter per his suggestion. When I was changing the plugs I noticed the two hoses attached to the sides box over the throttle body were cracked causing a likely vacuum leak. I replaced these hoses, and the miss went away.
The mechanic ran OBD2 diagnostics on the whole vehicle and gave it a clean bill of health. Everything's been fine for the past two weeks. Yesterday she called me and said her jeep just seemed to be working harder on the highway again. She pulled over, power-cycled the engine, waited a few minutes and drove it home.
So there's only a few things that I can think of that woulc cause such a cryptic issue:
First, some unseen vacuum leak somewhere which is causing running issues
or
The lockup in the torque conerter. I'm thinking the converter might not be locking all the time on the highway causing more slip and more revs, and not unlocking correctly at a stop causing the surging.
Has anyone else every experienced anything like this? I can't seem to replicate the problem. Are there any electronics or sensors that could fail and cause this issue? Is the converter electronically locking?
Honestly I'm at a loss. I hope this isn't a sign of a failing auto trans. My wife is a very conservative driver, and never beats on the vechicle at all.
Sorry for the novel, and thanks in advance,
-Matt