Time to "chip"?

[Defender]

Just got home from the "high country" towing a 30 foot 5th wheel with my '03 2500HD. Have pulled those same hills before without too much trouble. Today, I bogged down to about 30 MPH in one stretch. I am "chipping" illiterate so I am at your mercy. One guy told me there is only one chip GMC will use. True? Please make responses very detailed if possible. Thanks all. (I did a search but couldn't find answers to my Q's.)

[a5150nut]

With an 03 you wont be chipping. A computer reprogram might want to see John Kennedy vendor here on TDP. Or run a tuner.

But if it just started you need to be looking for the problem causing the loss of power. Do you have a SEL glowing? Have you pulled any codes?

We will need specifics on your rig and a little more info to help properly.

[Defender]

No codes.....Everything is stock.....150,000+ miles......thanks for the response.

[DmaxMaverick]

Start with a new fuel filter. Then a "chip".

[Kennedy]

Start with a new fuel filter. Then a "chip".

And a lift pump http://www.kennedydiesel.com/docs/Duramax%20lift%20pump.pdf

[Defender]

Thanks for the suggestions, folks. Going to start with the fuel filter. One thing that is messing with my mind is the fact that my MPG actually went UP even with the truck struggling. To my uneducated mind that doesn't make sense.

[DmaxMaverick]

Not unusual.The LB7's don't complain much about minor fuel restriction. Less fuel is, well, less fuel.

[Defender]

Thanks

[Mark Rinker]

Elsewhere on this forum, and quite a few years ago, I added the Kennedy Diesel "Tow/Haul A$$" chip to my LB7 trucks. I found them to be helpful when towing, overall better fuel consumption loaded and unloaded, and watched my engine oil go from soot laden between changes to translucent, indicating a more complete burn (i.e. the better mileage).

In addition to frequently changing fuel filters, I would also recommend regular fuel additive use. My favorite brand based on many Duramax towing miles is Howes. I also dumped alot of a cheap ATF down the throats of those LB7s and seemed to keep the injectors happy.

Call John.

[Defender]

OK, back again. Although no cel showing I took the truck in to see if it threw a code. It threw P0700 which is a Transmission Control Module. Is it possible this could be part of my issue? Also, would anyone know a ballpark number for repair on this? Thanks again.

[DmaxMaverick]

"P0700" is only a code in the PCM from the TCM that commands the SES/MIL lamp on, or to indicate there's a TCM code in history. If you never saw the SES lamp on, it's likely a (start/warm-up) passive diagnostic code in history (a ghost). You'll need a more capable scanner/reader to get the "real" P07xx code from the TCM. If you only find the P0700, then it's just a ghost, and means nothing. It is not likely to be part of your problem if the SES lamp is not on, in any case. If you haven't done it in a while, it wouldn't hurt to change the external spin-on tranny filter (don't forget the magnet!). Pressure/flow fluctuations can often cause "ghost" codes, and a loaded filter can cause that.

[Defender]

Thank you sir. Appreciate your time. Maybe I'll sleep tonight....lol

[Kennedy]

P0070 is one of those tricky codes. It essentially means little to nothing when no other codes are present and seems to pop up for no real reason sometimes.

I would just clear it and see if it comes back.