Hi, I have a 99 Suburban with very high miles. Going on 306K mostly highway miles. It's a 1500 with a 5.7 vortec engine This is our baby and the best vehicle I've ever owned. I hope someone can help because this is a solid vehicle that I think we can get more miles out of.
The problem is that it will intermittently surge or shudder between 40-60mph during acceleration. It's hard to pinpoint because it doesn't happen all the time. It seems to be worse if the vehicle is low on gas or the engine is cold but I'm not certain about that. It's not hard enough to call a buck, jerk, or sputter though. Maybe I've over-analyzing but basically it will shift to the correct gear and then back down then back up etc., and back and forth for very brief seconds. Then levels out after 60mph and there are no other problems. If the gas is low or engine is cold is does this in lower gears as well but usually only around 4th gear. I hope this description makes sense.
Here's where I'm confused. The transmission was rebuilt 2 weeks ago specifically the torque converter and rear planetaries. The day we got it back we performed a tune-up so all new plugs/wires/cap/rotor. The fuel filter was replaced about 8 months ago and the fuel pump 2 years ago. All regular maintenance has been performed on time since we bought it 4 years ago. Yesterday the Service Engine Soon light came on and it only showed one code (OBD II), PO161, so we replaced the 02 Sensor (Bank 2, Sensor 2).
However the problem persists and there are no other codes providing any direction. I've tried to search the internet for drivers with the same issue but the fixes vary too much and seem uncertain.
Other known issues in case that helps diagnostics: four wheel drive hasn't worked for years (haven't needed it in our flatlands) and ac compressor went out last spring.
Lost, not that I know very much about engines and transmission. Any thoughts? We bought it at a bargain and even with these recent fixes we have gotten our moneys worth. I really wish I could see this resolved. Thanks for reading and thanks in advance for any direction!
The problem is that it will intermittently surge or shudder between 40-60mph during acceleration. It's hard to pinpoint because it doesn't happen all the time. It seems to be worse if the vehicle is low on gas or the engine is cold but I'm not certain about that. It's not hard enough to call a buck, jerk, or sputter though. Maybe I've over-analyzing but basically it will shift to the correct gear and then back down then back up etc., and back and forth for very brief seconds. Then levels out after 60mph and there are no other problems. If the gas is low or engine is cold is does this in lower gears as well but usually only around 4th gear. I hope this description makes sense.
Here's where I'm confused. The transmission was rebuilt 2 weeks ago specifically the torque converter and rear planetaries. The day we got it back we performed a tune-up so all new plugs/wires/cap/rotor. The fuel filter was replaced about 8 months ago and the fuel pump 2 years ago. All regular maintenance has been performed on time since we bought it 4 years ago. Yesterday the Service Engine Soon light came on and it only showed one code (OBD II), PO161, so we replaced the 02 Sensor (Bank 2, Sensor 2).
However the problem persists and there are no other codes providing any direction. I've tried to search the internet for drivers with the same issue but the fixes vary too much and seem uncertain.
Other known issues in case that helps diagnostics: four wheel drive hasn't worked for years (haven't needed it in our flatlands) and ac compressor went out last spring.
Lost, not that I know very much about engines and transmission. Any thoughts? We bought it at a bargain and even with these recent fixes we have gotten our moneys worth. I really wish I could see this resolved. Thanks for reading and thanks in advance for any direction!
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