I installed a Delta Diablo almost two years ago and it has been working great. About a month ago on a trip to the mountains I started getting a check engine light when ever I accelerated fast, mostly when passing on the highway. At the same time I started having trouble starting the truck at alltitude, it would act like mabe it was flooded and would finally start after 3-4 times.
This weekend I made the same trip with the same problem, but this time it would not start after 6-7 tries. So I turned the key off, switched to stock tune and when I turned the key on I heard a loud pop! The engine started fine and I drove the 330 miles home with no problems and no check engine light when I passed.
My truck is a 2002 7.3 powerstroke.
Has anyone else encountered anything like this?
Thanks, Richard.

 

Does that mean that you pulled the chip, or is it a tuner?

 

If it's a Diablo, it's a three position flip chip. One of the three positions is stock, so I assume he merely switched it to that position.
A few things might have happened: your chip might have started to work loose from the circuit board it attaches to. The solution would be to be sure it's seated properly, then put a piece of duct tape over the chip, to secure it to the pcm. It's also possible that the problem isn't chip related, but running in the stock position coincidentally improved the operation of the truck. I'm not sure about SuperDuties, but on the first generation trucks like mine, there's a fuse under the hood in the fuse box on the driver's wheelwell that controls the pcm. It's commonly referred to as the "#9 fuse", because it's the ninth one in the box, when counting from the bottom. It's a 20 amp maxi-fuse, and pulling it for about 20-30 minutes will reset the pcm. It will also clear all stored codes, so if you intend to scan for codes, do it before doing this.
I hope this helps.