Engine/Transmission (1998.5 - 2002) Engine running rough

[JEllingwood]

when I start the engine it runs ok go down the road pulls good no problem, come to a stop engine idles down to about 1000rpms then runs real rough like it is missing. If you shut it off and restart it runs ok. have new fuel filter and have 12 to 14 lbs fuel pressure. any help??

 

[HBarlow]

How many miles on the odometer? Any modifications? Have you owned it since new? Do you know its service history and whether it has had modifications previously?

 

[JEllingwood]

I have owned the truck since new , dealer changed lift pump once then the injector pump then they changed the lift pump again by putting the pump in the tank shortly after that the injector pump went bad and I replaced it. I have added the FASS pump and have a HYPERTECH programer.

 

[JEllingwood]

114589 miles on truck

 

[HBarlow]

I would suspect the programmer.

 

[Hammer]

Hypertech was never known for a good diesel programmer thats for sure.

 

[JEllingwood]

what should I do now

 

[HBarlow]

Remove the programmer.

I don't know anything whatsoever about a Hypertech programmer. Has it permanently modified the factory program in your ECM or does it only modify when it is installed?

Often, when you use aftermarket devices like the programmer to modify your engine and then experience problems only someone who has experience with that device can offer advice.

 

[Newf Limo]

Hypertech. .

Here John,

I pulled this from their website...



Return Your Vehicle To Stock Tuning

BEFORE Taking Your Vehicle In For Service







If you take your vehicle to a dealer or mechanic for service, you must first remove the Hypertech Power Tuning and restore the stock programming. This is because diagnostic devices expect to find stock calibrations and will often overwrite the program if the latest stock calibration is not found in the computer’s memory. This will result in the loss of your Hypertech Power Tuning data. The Power Tuning can be easily removed to restore the stock tuning before you take your vehicle in for service, enabling the service technician to upgrade your stock calibrations. After the service is complete, you can reinstall your Hypertech Power Tuning. If you have any questions related to service issues, please call Hypertech at



901. 382. 8888



That would lead me to believe that you can return your trucks software back to its factory setting. I'm assuming it takes more than removing the unit(?). give them a call and see what they say. You'll need to make sure the default settings are in place before the Dealer hooks up the DRB III I am guessing. They could reflash your computer, maybe that would help. It does sound like a software issue. Just a shot in the dark.



It was weird listening to it purring along at idle, then suddenly sound like a couple injectors turned off. You have a very interesting issue.





.

 

[Newf Limo]

Hypertech was never known for a good diesel programmer thats for sure.

Any references for that? Maybe someone has already experienced and dealt with this issue. (?)