1993 Silverado C1500 Rough Acceleration - Help
 

Hey all,

I have a great 1993 Silverado C1500 5.7L V8 Automatic that has always taken care of me. Lately, I have been having some issues that I hope someone here can shed some light on.

Conditions: accelerating from 25 MPH thru 55 MPH (there is no problem below 25 MPH and after 55 MPH the problem lessens)

Symptom: When attempting to accelerate from 25 MPH to highway speeds, pressing the accelerator with gradual force will cause the engine to accelerate but quite roughly. You can feel the shaking of the engine. Accelerating going up-hill makes the shaking worse.

Workaround: I have found that pressing the accelerator down a bit further until you feel it change gears will cause the shaking to be less pronounced, but you can still feel it.

So far the fuel filter has been replaced, spark plugs are fine, engine timing has been adjusted to no effect, and the rotor button (distributor) has been replaced.

If you can shed any light on what might be going on here, I would love to have my truck drive like it used to!

Thank you in advance!
-Fred

Any help would be appreciated!

Ok. Any codes from a check engine light? Check your bolts on your intake manifold and the throttle body. Sometimes they will loosen up causing vacum leaks. Look at the throttle body flaps and see if you notice any black sludge build up on them. Would be better if you just take it off and throughly clean the whole thing with some brake cleaner. Check the hose going to the PCV valve for cracks. Start there and see if you notice any change.

With the engine shaking I would check the engine mounts and the transmission mount. The only other thing I can think of is maybe the wires are breaking down since you changed the plugs already... Also since you changed the plugs the wires, cap and rotor is a good thing to change while you are at it... aka a complete tune up.

Thank you for these suggestions! I will look into them and post the results.

Fred