I have a 1997 GMC Sierra with a 5.7L V8. I am experiencin g a shudder when
coming out of power when climbing a hill or coming out of a powered
situation. It happens like clockwork when coming over the top of a hill.
Once accelleration is applied it stops. 2 mechanics have referred to it
as an issue with the torque-converter lockup. I have read a few comments
online about a misfire causing this when at low rpm's, which is when this
seems to happen. Any help would be greatly appreciated.
It could be the torque convertor not coming out of lockup when it should
(produces the same shudder as a 5-speed in 5th gear @ 25mph with yer' foot
on the gas), or, more likely, a misfire being caused by a weak ignition
component, exacerbated when under serious load.
If your TC was truly malfunctioning, you'd likely have DTC's stored in the
PCM, as your transmission is electronic (4L60e) and controlled by the PCM.
When's the last time she had a major tune-up (plugs, wires, cap and rotor)?
When's the last time you had the trans fluid and filter
changed? Torque converter lockup clutches are sensitive to fluid
quality, and can cause a shudder just as you describe. If it's more
than 30,000 miles, get the old fluid out of there.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.