Hello,
I have an issue that has just started with my 2003 Trailblazer Ext 4.2L engine and 4wd with 252,000 miles. I cruise along at between 45 and 55 mph with the transmission in OD and torque converter locked up, rpms between 1400 and 1600. Then I step very slightly on the gas to accelerate and I feel a slight bobble in either the engine or transmission. I have to accelerate slowly enough that it does not unlock the converter or downshift. Some of the time I just feel a bump, but the rpms don't move. Other times I see the rpms jump slightly then drop back. Once I get to 1700 rpms, a little over 55 mph all is smooth again. From 60 mph on up there is no evidence of problems. At hiway speed the transmission will unlock and then downshift if I step on the gas hard enough and feels normal. Below 45 the transmission is not shifted into OD or locked up. There is no check engine light on. The bump is very slight, such that if I'm on a bumpy road I can't tell the difference between the road and the problem. On a smooth road, it is very noticable however.
Can this be the torque converter? It feels like the engine is misfiring occasionally (just a subtle bump at random intervals) but it only occurs at the very slowest speed that allows the torque converter to lock up. It does not happen at slower speeds in a lower gear, but the same rpms. It does not occur at slightly higher speeds. I would have thought that if the engine were misfiring the computer would detect it and set the check engine light. I don't feel any evidence of slippage in any of the gears.
To give a full history, about 4 months ago, at about 240,000 miles my trans had gotten really soft in the shifts, especially the 2 to 3 shift. Under light to moderate acceleration the rpms would flare as it made the shift. I did a complete fluid flush and changed the filter, but it had almost no effect. I read on the forums about the corvette servo hardening up the 1-2 and 2-3 shifts, so I got one and tried it. It worked very nicely. The lower shifts are nice and solid now. The shift to 4 is still rather soft but once engaged it is solid, and the TCC lockup has seemed to get even slower than it used to be. A very soft slide into lockup which I hate. I've read here about the problems with the TCC lockup valve getting worn, and the transgo shift kit fixing these kind of problems.
If it is the torque converter, will a shift kit likely fix it? If it is the engine misfiring, wouldn't the computer record the misfire and set the check engine light? Any guidance would be appreciated.
I have an issue that has just started with my 2003 Trailblazer Ext 4.2L engine and 4wd with 252,000 miles. I cruise along at between 45 and 55 mph with the transmission in OD and torque converter locked up, rpms between 1400 and 1600. Then I step very slightly on the gas to accelerate and I feel a slight bobble in either the engine or transmission. I have to accelerate slowly enough that it does not unlock the converter or downshift. Some of the time I just feel a bump, but the rpms don't move. Other times I see the rpms jump slightly then drop back. Once I get to 1700 rpms, a little over 55 mph all is smooth again. From 60 mph on up there is no evidence of problems. At hiway speed the transmission will unlock and then downshift if I step on the gas hard enough and feels normal. Below 45 the transmission is not shifted into OD or locked up. There is no check engine light on. The bump is very slight, such that if I'm on a bumpy road I can't tell the difference between the road and the problem. On a smooth road, it is very noticable however.
Can this be the torque converter? It feels like the engine is misfiring occasionally (just a subtle bump at random intervals) but it only occurs at the very slowest speed that allows the torque converter to lock up. It does not happen at slower speeds in a lower gear, but the same rpms. It does not occur at slightly higher speeds. I would have thought that if the engine were misfiring the computer would detect it and set the check engine light. I don't feel any evidence of slippage in any of the gears.
To give a full history, about 4 months ago, at about 240,000 miles my trans had gotten really soft in the shifts, especially the 2 to 3 shift. Under light to moderate acceleration the rpms would flare as it made the shift. I did a complete fluid flush and changed the filter, but it had almost no effect. I read on the forums about the corvette servo hardening up the 1-2 and 2-3 shifts, so I got one and tried it. It worked very nicely. The lower shifts are nice and solid now. The shift to 4 is still rather soft but once engaged it is solid, and the TCC lockup has seemed to get even slower than it used to be. A very soft slide into lockup which I hate. I've read here about the problems with the TCC lockup valve getting worn, and the transgo shift kit fixing these kind of problems.
If it is the torque converter, will a shift kit likely fix it? If it is the engine misfiring, wouldn't the computer record the misfire and set the check engine light? Any guidance would be appreciated.