On 2013-10-08, Stormin Mormon wrote:
Ignoramus3720 fired this volley in
:

I have a problem that I noticed with my pick-up truck.

The problem is that at certain speeds, such as 40-45 MPH, I feel
vibration if I step on the gas pedal and try to accelerate. If I let
go of the gas pedal, vibration stops even as the truck continues to
drive forward. It has gotten worse lately. I have thought a lot on
what could cause it. It does not seem to be related to the engine
RPM. I watch the RPM vary and the vibration does not vary with it.

What could it be?

i



What kind of truck, age, mileage, engine size and all?

I've been thinking about this, last few hours. With
the "worse on accel", it sounds familiar. One email
friend of mine suggests it might be tune up and
ignition related. Might be missing on one cylinder,
which is worse on accel (timing advance).

Certainly a possibility.

i