Loosing Acceleration Completely

[bmzebrin]

I am new to the whole forum thing, but I can't figure out what is wrong with my dad's truck and I figured I might get an answer here. Anyway when you are driving along and get off the gas and then go to get on it again nothing happens. You can push the pedal but there is no acceleration the truck just coasts. Then maybe 15-30 seconds later a lot of black smoke comes out of the exhaust and then the truck will run fine for a couple days. It happened to mine once and then no more problems, but mine had been sitting for 3 months so I figured it just needed blown out. It has been going on for about a months maybe twice a week.

 

[DR.Diesel]

could be a hung open egr valve .have it scanned and see if the computer has stored any codes

 

[hheynow]

Anyway when you are driving along and get off the gas and then go to get on it again nothing happens.

Your diesel has a gas pedal?

 

[snicklas]

bmz,

Also, the 6.0 is a "fly-by-wire" design. The throttle pedal is electronic, this is from the 6.0L Bible:

The AP (accelerator Pedal) is a three track pedal. the AP incorporates three potentiometers. Through out the movement of the AP the resistance values of the three potentiometers must agree. During the movement of the AP if one of the three potentiometer readings do not agree, the check engine light will illuminate and the vehicle will continue to perform as normal. If two signals from the AP are lost the PCM iwll allow tje rngine to only idle and illuminate the check engine light. The three-track pedal is a safety feature. The three track pedal takes place of the Idle Validation Switch allowing for limited system failure and still maintaining performance.

I wonder if the accelerator pedal in your truck is starting to fail somehow. I have not had problems with mine, but I have read about trucks that have had to have the AP replaced and the truck was fine after that....

 

[jpringle83]

I had this problem but the truck wouldn't even be drivable. It would do nothing if you floored it and then uncontrollably brakes and all would try to rocket out from under you. It's actually quite the scary feeling kinda like driving a newer toyota. It wasn't so funny however when I had to go calm the wife down because it started while she was towing her horse home. Somehow it was my fault. I would second the sticking egr valve. Just about every problem the 6.0 has boils down to the egr valve. My old mechanic told me yesterday that in their fleet they have done the egr delete and having had any drivability issues on them since plus the trucks run cooler and get better mileage. I think everyone with a 6.0 should at some point consider it. Mine's getting done next year when my extended is up.

 

[bmzebrin]

thanks

thanks for the incite. i will look into the egr valve. that sounds like it may be the problem.