I was cruising up to the local movie theater with my fiancee and two friends, the darn truck is driving good and strong, and all of a sudden for no reason (well no obvious reason) the CEL flips on, and the engine runs really poor and rough, like 4 cylinders are firing, and the rest just shrugging along, I give it throttle, let go of the throttle, try a quick pump, nothing, after about ~10 seconds it goes away and its driving strong again, we're all like "hope that is just a fluke" and after about ~10 miles up the road we get to the movie, watch it and leave... on the way back, it happens A L O T over and over...

Long story short I can start the truck just fine, it idles just fine, and shifts fine, but when you accelerate from idle its good, and as long as the accelerator has "any" amount of fuel past idle going to the engine, its goos.. BUT!, when you let go of the accelerator, it is about a 50/50 chance that it turns on the "safe mode" and runs rough etc... It never "dies" but it definitely throws a code... (I haven't checked it yet) and well, it'll barely push enough power to get to 40 mph (if you keep trying to drive it,)...

However, if you drive the truck, accelerate, let go of the accelerator, trigger the CEL, and let go of everything but the wheel, let it idle, roll, whatever, it takes ~4-5 seconds, consistently, and the CEL turns off, and its suddenly normal again, but if you accelerate, and let go of the accelerator, it repeats...

I've tried it in 4WD, 2WD, popping the accelerator, gradually releasing/engaging the accelerator, its consistant.

1- Start Engine - good
2- Idle - good
3- Accelerate - good
4- Drive with some power to the motor - good
5- Lower the acceleration/Idle/Coast/Decellerate - Starts the symptoms
6- Let it coats/Idle/roll ~5 seconds - Symptoms go away
7- Accelerate - good
-- Idle/Coast.. etc. (repeats at #5)

Its kinda driving me nuts.... I can't figure it out... (granted its only been doing it a few hours and its after midnight... but its keeping me up...



Thoughts?

 

step 1: check the codes to see why the CEL is coming on.
step 2: post the codes here so we can help you.

 

By the way, welcome to FTE!

 

Sounds kinda like mine, except w/o CEL and not as often. I am interested to see what comes up on the codes.

 

I would say start with the basics. How long since your last fuel filter? Drain the fuel bowl and look at it's contents. (maybe some water) Next, and the biggest thing, clean the fuel pressure regulator screen. This is a big hitter.

Pull the fuel filter out. Inside the bowl at the top on the drivers side is a hole about the size of a fat pen. Look inside there with a mirror and light. You should see a nice clean fine mesh screen. If not, you need to clean it. Some people say pull the regulator to clean it, but I don't. Too easy to lose parts. Take some Q-tip sticks....NO COTTON, just the sticks and lightly brush the crud off of it until it's a shiney screen again. And don't let it fall in the bowl. After that's done, put the filter back in and start it. Let it run for about 5 minutes. Then check your fuel pressure.

You can check the fuel pressure by using a tire psi gauge that goes to 80psi if you don't have a normal gauge. On the drivers side of the regulator there is a schrader valve (tire air valve) That's where you check it. Get lots of rags cuz this will make a fuel mess, but at least you can check your fuel psi. And you have to hold it on there for at least 10 or so seconds. It will "pulse" untill you get your highest reading. You are looking for 50 to 60 psi. See if that get's you up and running. If not, I'll go further. Hope that helps.