Engine hesistation when cruising
been using the AC? had your timing belt changed?
the AC makes the ECU do extra stuff, might be malfunctioning. this one unlikely.
the timing belt: you have changed it already IIRC. how long ago? the belt could be fatigued, although I think you would notice some power issues under WOT if that were the case. not to metion it's an auto tensioning system, although that could be the cause too. If the tensioner pulley is nearing it's lifes end it could be dragging a little all the time and catching occasionally. grasping at straws in this dept though, as you would see the issue more often than not.
o2 sensor seems unlikely, you would see a cel already if those values were off. does it feel like it's cutting fuel, or just losing power. how you have described it sounds like fuel cut, and if it's fuel cut caused by the o2 sensors you would definitely have a cel.
a wideband would be very useful, but that's limited. do you have the tactrix cable? even with it's limitations on the RA it will give you a decent idea of what the ECU is seeing.
the AC makes the ECU do extra stuff, might be malfunctioning. this one unlikely.
the timing belt: you have changed it already IIRC. how long ago? the belt could be fatigued, although I think you would notice some power issues under WOT if that were the case. not to metion it's an auto tensioning system, although that could be the cause too. If the tensioner pulley is nearing it's lifes end it could be dragging a little all the time and catching occasionally. grasping at straws in this dept though, as you would see the issue more often than not.
o2 sensor seems unlikely, you would see a cel already if those values were off. does it feel like it's cutting fuel, or just losing power. how you have described it sounds like fuel cut, and if it's fuel cut caused by the o2 sensors you would definitely have a cel.
a wideband would be very useful, but that's limited. do you have the tactrix cable? even with it's limitations on the RA it will give you a decent idea of what the ECU is seeing.
yeah mine's doing the same thing...most noticably around highway speeds for me...i either have to be pushing down on the gas or letting off it...if i get the throttle just in that right spot it hesitates...but mines been doin that almost since i got it...
Alright, I think I fixed it, and I feel kinda dumb 
Yesterday, my car threw another 2138 code, so I coasted to the side of the freeway and thanked myself for keeping my code reader/resetter in my glovebox As I was heading home, I realized that the hesistation wasn't happening when I had the cruise control on. So all my attention went to the accel. pedal position sensor. Seems like it had a loose connection. I unplugged it and replugged it and the problem went away. I'm going to throw some electrical grease on it this weekend and hopefully it won't come back.
For those that don't know, the sensor works by sending a smooth and gradually increasing/decreasing voltage level, based on where you have the gas pedal, to the throttle body. I'm guessing the connection was off just enough that the really low voltage signal, that would come with cruising with the pedal barely pressed, wasn't getting through cleanly, causing the TB to flutter.
Hopefully the problem won't return. If it does, I'll have to replace the sensor, which costs about $160
Yesterday, my car threw another 2138 code, so I coasted to the side of the freeway and thanked myself for keeping my code reader/resetter in my glovebox As I was heading home, I realized that the hesistation wasn't happening when I had the cruise control on. So all my attention went to the accel. pedal position sensor. Seems like it had a loose connection. I unplugged it and replugged it and the problem went away. I'm going to throw some electrical grease on it this weekend and hopefully it won't come back.For those that don't know, the sensor works by sending a smooth and gradually increasing/decreasing voltage level, based on where you have the gas pedal, to the throttle body. I'm guessing the connection was off just enough that the really low voltage signal, that would come with cruising with the pedal barely pressed, wasn't getting through cleanly, causing the TB to flutter.
Hopefully the problem won't return. If it does, I'll have to replace the sensor, which costs about $160
Last edited by otter; Aug 10, 2007 at 10:47 AM.
Alright, I think I fixed it, and I feel kinda dumb Yesterday, my car threw another 2138 code, so I coasted to the side of the freeway and thanked myself for keeping my code reader/resetter in my glovebox As I was heading home, I realized that the hesistation wasn't happening when I had the cruise control on. So all my attention went to the accel. pedal position sensor. Seems like it had a loose connection. I unplugged it and replugged it and the problem went away. I'm going to throw some electrical grease on it this weekend and hopefully it won't come back.
For those that don't know, the sensor works by sending a smooth and gradually increasing/decreasing voltage level, based on where you have the gas pedal, to the throttle body. I'm guessing the connection was off just enough that the really low voltage signal, that would come with cruising with the pedal barely pressed, wasn't getting through cleanly, causing the TB to flutter.
Hopefully the problem won't return. If it does, I'll have to replace the sensor, which costs about $160
Yesterday, my car threw another 2138 code, so I coasted to the side of the freeway and thanked myself for keeping my code reader/resetter in my glovebox As I was heading home, I realized that the hesistation wasn't happening when I had the cruise control on. So all my attention went to the accel. pedal position sensor. Seems like it had a loose connection. I unplugged it and replugged it and the problem went away. I'm going to throw some electrical grease on it this weekend and hopefully it won't come back.For those that don't know, the sensor works by sending a smooth and gradually increasing/decreasing voltage level, based on where you have the gas pedal, to the throttle body. I'm guessing the connection was off just enough that the really low voltage signal, that would come with cruising with the pedal barely pressed, wasn't getting through cleanly, causing the TB to flutter.
Hopefully the problem won't return. If it does, I'll have to replace the sensor, which costs about $160
You sitters will never know what it's like to have a clean ***.
Aaaand mine finally died.
Just finished a fun series of curves on a lonely backroad on my way home, when the car lost almost all power and the CEL came on. Coasted off the road, and got out my code scanner. P2138. Restarted the car, and crawled the rest of the way home.
It had been doing the same hesitating occasionally while cruising on the highway, I had also noticed it never did it with cruise control on. I had been planning to replace the sensor sooner or later, guess its time is now.
Just finished a fun series of curves on a lonely backroad on my way home, when the car lost almost all power and the CEL came on. Coasted off the road, and got out my code scanner. P2138. Restarted the car, and crawled the rest of the way home.
It had been doing the same hesitating occasionally while cruising on the highway, I had also noticed it never did it with cruise control on. I had been planning to replace the sensor sooner or later, guess its time is now.
Aaaand mine finally died.
Just finished a fun series of curves on a lonely backroad on my way home, when the car lost almost all power and the CEL came on. Coasted off the road, and got out my code scanner. P2138. Restarted the car, and crawled the rest of the way home.
It had been doing the same hesitating occasionally while cruising on the highway, I had also noticed it never did it with cruise control on. I had been planning to replace the sensor sooner or later, guess its time is now.
Just finished a fun series of curves on a lonely backroad on my way home, when the car lost almost all power and the CEL came on. Coasted off the road, and got out my code scanner. P2138. Restarted the car, and crawled the rest of the way home.
It had been doing the same hesitating occasionally while cruising on the highway, I had also noticed it never did it with cruise control on. I had been planning to replace the sensor sooner or later, guess its time is now.
holy crap...I saw the OP was otter, and thought wow, another epic resurrection from some noob...boy was I wrong...how's the car doing otherwise?
Running like a champ otherwise. Car has 170,006 miles on it now.