This relates to a 2002 Buick LeSabre with a 3.8L engine, but I assume the same general principles would apply to most cars with the same problem.
Occasionally the throttle briefly resisted moving when pressed. Then, when enough pressure was applied, it would release and function normally. This seemed to be happening more frequently and the pressure required to release him grew greater.
Time to look at it!
The first step was to remove the plastic cover that covers the motor. This can be easily done by unscrewing the oil filler nozzle (the 3-inch extension that the oil filler cap fits into), unscrewing it a half turn, and lifting it up. This exposed the body and mechanism of the fuel injector.
By manually working the sector pulley that was activated by the throttle, I concluded that the throttle was stuck in the closed position. But how to get it was the problem!
I removed the rubber boot between the air box and the fuel injector body. But this revealed a “screen” that fully covered the intake!
That “screen” was held in place by a “C” ring which I then removed. But the “screen” didn’t come off easily. It is not a flat screen; It is a piece of honeycomb about 1/4 inch thick. It worked best to work it out a little around the circumference and going around a few times. I used the blade of a knife to pull it out, but next time I would use a wire with a hook on the end to go in and pull it out from the inside.
- I think its purpose is twofold:
- Create a laminar airflow in the chamber and
- Serves as a “heat absorber” or flame arrestor in the event of a counterproductive effect.
Once it was removed, I was able to see the butterfly and could practically confirm that it was where the problem was. I cleaned it around the circumference, but it still stuck. Then I put some AMSOIL MP (something like WD-40) on the throttle shaft bushings.
That worked! No more sticky!
How long it will stay that way remains to be seen!
If it fails again, I will remove the throttle position sensor at the front of the injector body. That should expose one end of the throttle shaft, and that was the end that gave the most trouble this time. (This requires a Torx key to remove).
What was the cause? I really don’t know. It acted like there was “old grease” in there sticking to it, but I doubt it was grease lubricated. Maybe “sticky stuff” in gas over 60k miles?
Copyright 2007 by Keith A. Williams
