Engine bucking in overdrive

[dgogley]

Hello all, I am fairly new to this forum. I have a question concerning my 1996 Lesabre. I purchased this car used currently has around 83,000 miles on it. I have put plugs, wires, fuel filter etc with the exception of the coils. Seems like after 10-15 min of driving when the engine shifts into overdrive (around 55-60 mph) under load I can feel it jumping/bucking. I can even watch the tach jump as I am feeling this. If i put my foot into it and kick it in a lower gear it seems to be somewhat better. It seems to be worse with the A/C on and going up hill. I know its hard to pin point something like this but I was curious if any of you had by chance had simular problems? I love the car, rides like a dream. I never thought I would say this but its better then any Cadillac I have owned in the past. Gas mileage etc. Any help would be appreciated!

[public]

Check the vacuum modulator. It is an easy repair/replacement to do at home. Cost is about $10-$15. You may also look at the the Idle Air Control Valve, and I have seen other electronic componients be heat sensitive. A Haynes manual will tellyou how to test these componients.

[dgogley]

Originally Posted by public

Check the vacuum modulator. It is an easy repair/replacement to do at home. Cost is about $10-$15. You may also look at the the Idle Air Control Valve, and I have seen other electronic componients be heat sensitive. A Haynes manual will tellyou how to test these componients.

Can you tell me where the vacuum modulator valve is located? I also cant find my pcv valve on this car? Thanks guys

[public]

I believe it is located on the front side of the transmission under the intake snorkel. I will be the only part on the transmission with a vacuum line going to it. As for the PCV it should be in one of the valve covers ???
Good Luck.

[public]

P.S. You may also have a 4T65E transmission (I believe they were available) which has no modulator. That function is done by the computer. I think it will say on the label under the hood.

[auto trainy]

As far as the PVC,it is located in the upper intake manifold on top near the belt area.

[dgogley]

Originally Posted by auto trainy

As far as the PVC,it is located in the upper intake manifold on top near the belt area.

Thanks Auto I finally found it. Have never see a set up like that before. Do the "O" rings come with the new PCV valve and what is the sensor on top of it for? Just says "pressure"

[jase386]

Before you get into too much expense, check the coils, friend of mine had the same problem with a 93 regal at the same mileage, had tune up and trans serviced, before discovered it was 2 bad coils

[fredfast]

Hi I hope this is still helpful. I drive a 97 and have spent many dollars on this problem. Until the latest diagnois ( by an independent tech) everyone pursued electrical. The latest diagnois, transmission Torque converter clutch.
RABarrett, in another thread also identified the TCC as a problem.
I never had a fault code for this condition.