uphill shudder in automatic 4th gear

[sbbob]

Hi, I've got a 93 GP, ~95K miles, 4sp automatic transmission, fuel injected, 3.1L V6, generally runs OK. It just started shuddering/stuttering on medium uphill grades, only in 4th gear around 40-50 mph. 3rd gear is smooth and shifting between gears is smooth as well. It will shift into 4th on the grade and start to shudder right away; it also will shudder if I enter the climb already in 4th.

Any ideas? I plan to have it serviced but want to make sure I can explain it OK to the mechanic.

[troy1]

could be a converter slip or 4th could be slipping, also it could be a engine problem do to the fact your really starting to load down the engine in 4th

[wlkjr]

New plugs and wires cured that on my mother's Buick.

[GTP Dad]

Try having the transmission scanned with a trans capable scanner. Sounds like the Torque Converter Clutch Solenoid to me. Will cause shuttering due to not engaging and disengaging properly.

[sbbob]

Thanks for the feedback.

Two developments: the problem spread to other gears, and then the engine very suddenly began to sound like it had a serious exhaust problem. (i.e. it sounded like a Harley Davidson). The mechanic found one spark plug had become disconnected, and expects new spark plugs to resolve the issue.

[richtazz]

Make sure you use quality OEM style plugs, no fancy schmancy multi-electrode Bosch junk!!! I'd put a new set of wires on her too while you're at it.

[sbbob]

Back in shape!

Installed new spark plugs, and both problems (shudder and loud exhaust) are gone. Plus the mechanic used non-fancy-schmancy plugs (The old ones were Bosch). Thanks!

[richtazz]

Thanks for the feedback. We like hearing happy endings.

[Chris Stewart]

I had a vehicle w/120K do the going up a grade OD shudder...fluid and filter change fixed it.