QuestionI have a 1998 GMC Yukon 4x4. I recently noticed that I am feeling some
odd vibration coming through the gas pedal when I am lightly pressing
on the pedal and traveling between 35 - 45 mph. It only happens in the
first 5 minutes of driving the vehicle. After about 5 minutes of driving
or if you are firmly pressing the gas pedal the vibration disappears. The
engine is running fine and the transmission seems to shifting just fine.
AnswerI have not had this particular complaint before, and I actually own a 1998 Tahoe 4x4, but I think I may have an idea of what it may be try an engine decarbon.
The way that I like to do an engine decarbon, which is how I do it on my 1998 Tahoe, is to go to your local GM dealership and get a can of GM spray top engine cleaner, and a can of liquid top engine cleaner. Take the air induction off of the truck and start it, spray the first can into the throttle body making sure to manually work the throttle to keep the engine running, and clean the throttle body. Next, pour the liquid top engine cleaner into the throttle body, again keep the engine running, and when the can is about 3/4 empty dump the can in and let it stall the engine. Put the air induction system back on the truck and disconnect the battery to clear ant codes set by this and let it sit for 30 min. Then start it up, this will be somewhat difficult because it will be flooded, and drive it. Try to keep the RPM's high for a while. There will be alot of smoke coming out of the tailpipe, drive it until the smoke is at least almost gone and see if it is better. If not get back with me. The top engine cleaner should be about $7-10 each.
