My Truck Has a Mind of Its Own

[drice]

Here's the deal it doesn't matter what speed I’m at but it usually happens about 65-80 mph. The truck will start stuttering (for lack of better description) and if I let off the gas the truck will continue at that or a faster speed. I usually have to hold the break till it slows down. I have looked through the search and have not seen anything like this besides the turbo runaway stories. Last night I set the cruise at 67 and then I looked down and I was running 85. My first thought is throttle position sensor. I have ordered one should be here today. But I have never heard of one malfunctioning that way usually it is a drop to idle. Next thought is injectors. And last thought turbo. Has anyone had this happen or could think of reasons.



03 HO DR P and bully dog power pup FASS system DTT trany that’s about it.

 

[JCleary]

I would unplug your pressure box as a first step of diagnosis...



My '03 did weird things (throttle related) with two of the many pressure boxes I tried. I unplugged all the connections, applied dielectric grease and reconnected. It solved the problem.



If removing your DR. P. doesn't work, try downloading the stock program. I have heard of some softwares (not necessarily Bully Dog) being a bit "unstable. " IIRC it was a custom tune, but eliminating another variable is a good thing.



My experience has told me to look at aftermarket components first for failure. Typically they're not designed with as much concern for longevity as the items engineered by Cummins or DC.

 

[DonFitzwater]

I agree with isolating the aftermarket goodies. My 06 with Edge EZ will do something very similar to what your truck is experiencing. Not quite so fast though. It seems so continue fueling aggressively and finally winds down after about 8 seconds... ... ... . kinda unnerving the first time it happened to me.

 

[JCleary]

I agree with isolating the aftermarket goodies. My 06 with Edge EZ will do something very similar to what your truck is experiencing. Not quite so fast though. It seems so continue fueling aggressively and finally winds down after about 8 seconds... ... ... . kinda unnerving the first time it happened to me.

On your truck, it's a combination of two things...



First, the programming on newer CR trucks is designed to prevent turbo-bark. When you release the throttle, it will run on a bit and ramp the throttle down to protect the turbo. Second, the EZ raises rail pressure. When the throttle is released, the injectors take a bit longer to drain the pressure from the rail, resulting in some run-on.



My '03 HO did not have the turbo-bark protection thing going on, but whenever I had a pressure box plugged in I would have some run-on.





When hustling my truck along, I actually learned to lift the throttle before pushing in the clutch to shift, otherwise the rpm's wouldn't drop for the next gear. It took some practice, but I was actually able to time it perfectly.



I haven't run any pressure on my '07, but I notice when lifting the throttle it will continue to drive forward for a bit. I find it annoying. I would rather bark the turbo...



It will give me a reason to upgrade when it breaks!



On edit:



I don't like Fords, but they came up with a good way to prevent turbo-bark. On our six-leakers the turbos barked all the time. After multiple reflashes, it stopped. They reprogrammed the variable vanes to choke the exhaust when you let off the throttle, keeping drive pressure up and keeping bark from happening. I wonder if the new 6. 7's do this, or if they exhibit the same annoying fueling ramp that our trucks use?

 

[betterthanstock]

If it went up in speed on C/C, I would suspect the c/c mechanism. Yours has a cable (actually 3 cables for an auto). Make sure none is rusted. The vaccuum actuator, or vac pump may be to blame too.

 

[drice]

THAKS FOR ALL THE HELP i AM STILL LOOKING FOR THE PROBLEM i HAVE REMOVED THE DR P AND IT HAS NOT RUN AWAY BUT IT STILL HAS A BAD STUMBLE WHEN YOU HOLD IT AT CERTIAN SPEEDS. AS FAR AS THE TURBO BARK PROTECTION MINE MUST NOT WORK CUZ i CAN BARK IT AT WILL AND IF I'M GETTING ON IT IT WILL BARK 5 OR 6 TIMES IN A ROW BUT THERE IS MIN PLAY IN TEH SHAFT. THANKS AGAIN AND KEEP THE IDEAS COMING

 

[MA2LA]

I wonder if the regulating valve on the cp3(can't remeber the exact name) is having problems.