reduced engine power

[Fin_Woozle]

I've been having this problem with my '06 2500HD LBZ. Every once and a while when I'm accelerating the REP message pops up at the DIC and the computer takes over the gas pedal. If I try to floor it it'll only go about 25. But if I gently push the pedal with the tip of my toe it'll eventually climb up to 55. Message disappeares and everything returns to normal if I turn off the ignition for 30 seconds. Sometimes it may be ok for weeks and then do this twice in one day. I've noticed that the problem is almost always related to heavy acceleration and I think it's more common in wet conditions but can't say for sure. Load seems to have nothing to do with the problem.

The truck is stock except for the plow installation and a speed limiter. I've plugged in my scanner but it doesn't show any codes even with the REP message still in the DIC.

Any thoughts on this one...?

Ps. I know someone will ask about the speed limiter so I might as well explain it. I live in Finland and because of some BS EU law all trucks (10/2001 and newer) with GVWR over 7700 lbs have to be equipped with a speed limiter set to 55. It really sucks, I know...

[Mark Rinker]

How is the speed limiter implemented? ECU reflash...or???

[Fin_Woozle]

It's a separate device (Groeneveld) which to my understanding has been installed between the gas pedal assembly and the ECU. So when the speed gets near the limit it overrides the signal from the gas pedal and reduces the acceleration. I have to admit that the thought has crossed my mind that it could be the source of the problem but on the other hand the problem occures mostly at lower (25-45) speeds. I guess the only way to know for sure would be to unplug the limiter from the truck but I'm trying to avoid that since all the connections and wires have been sealed and of course unpluging the limiter is illegal...

I think the easiest (and the best) way to implement the limiter would have been the ECU reflash but since the limiter has to be "untamperable" (I don't know if thats even english but I hope you get the meaning) and anyone with the right programmer could easily erase the ECU speed limit the separate device is how it has to be done.

[mdors]

Had the exact problem with my '06 LBZ. It came on gradually when passing a vehicle, etc. I had a predator with the 65hp program installed. The truck had about 11000 miles on it. I started reading posts on this site and read one concerning the fuel filter. I changed the fuel filter and that solved the problem.

[SoTxPollock]

FIN WOOZLE, In Texas if someone dared to do that not only would we unplug the limiter, but also the person from holding a position in the government.
What happens if one needs to accelerate in order to get out of the way of another vehicle and cannot avoid the accident because they can't accelerate? That really is BS.

[Mark Rinker]

In Minnesota, we'd pass a new law limiting commercial trucks to 55mph (like California) and let police enforcement issue lots of tickets. The government officials would vote themselves a new pay raise with the additional revenues, roads would continue to deteriorate. (Commercial drivers would continue to speed - just not around known police enforcement areas!)

Sounds like you could reflash your ECU and get around the speed limiter, or at least bump it up a few percent...

[mark45678]

Not sure what the code is that your seeing but it sounds like the motor goes into protect mode. Will it rev over 2000 rpm? if not when was the last time you replaced your fuel filter? more then 10000 miles or 200 engine hours?

[colt49]

Your Laplander Lawmakers would crap if they saw 5000 AMERICAN TRUCKS Blow into town in a convoy with rifle racks and ropes hanging in the back windows!!! Norway has some very bad laws. I'm glad the USA still lets us make our trucks like we want. The government tried that 55 MPH law in the 70's and made the auto industry make junk underpowered smog smothered cars and trucks. This is a prime example of what Americans should watch out for again with stupid lawmakers solving our problems and all these lawmakers have DUI's, bankruptcies, back owed child support etc. Congress is full of losers if you read about each and everyone's profile. The revealing factor is they have to expose theirselves for all research on their personal info to the public to be in an elected office. We have our situations too but we at least can run our trucks like we want for the most part!!! Look at the flag today and remember this story from Norway. They aren't free.

[Fin_Woozle]

I'll try replacing the filter since it's coming up in the near future anyway. I sure hope it's something that simple.

To be sure it's not the limiter messing my truck up, I could try cutting the wire from the speed sensor to the limiter and reprogram the ECU for the ~55 mph limit via OBD2. I only have general OBD2 software and nothing GM specific, so I'd have to do it manually using a terminal program. The only problem is that I have no idea what the commands for altering the speed limit are...

mark45678 - It'll rev above 2k if I push the gas pedal gently. Otherwise it'll limit revs to 2k. The message "reduced engine power" appears on the DIC. No DTCs appear during or after the message. The truck (and the filter) only has about 4k miles and 270 engine hours on it.

colt49 - I'm not sure what kind of laws our northern neighbor has. I assume EU regulations don't apply there since Norway is not a member of the European Union. Touching post (I could almost hear "The Star Spangled Banner" playing on the background), but in my opinion a bit off-topic.

[Kennedy]

Fuel filter first, and consider adding fuel lift supply pump(s) to get best life from your filters and most consistent performance.

[Fin_Woozle]

Similar to the one in the 6.5td?

[Kennedy]

I actually make a kit specific to the Dmax. Listed on my site under Dmax Parts/Lift pump or Pump-filter combo.

[jbplock]

Similar to the one in the 6.5td?

John's Lift Pump is the way to go but the 6.5TD (AC EP158) pumps will work too .. I have one on my 03 ... Duramax Lift Pump & Pre-Filter

[Fin_Woozle]

Ok. Thanks John and Bill.

[Kennedy]

The 6.5 pump is OK for general use, but as the HP increases, we see a need for more volume yet. My single pump might get a guy by, but teh twins are pretty much always successful with the LLY and LBZ fuel issues.

[mdors]

Had the same problem this morning. Truck was running fine I stopped for a traffic light. When I went to accelerate the truck would not go faster than 25 mph. Check engine light came on. I let the truck idle for 2-3 minutes and problem went away. I checked the trouble codes and p0106 manifold absolute pressure and p0700 transmission condition codes appeared. I have a S&B filter, 4" turbo exhaust and preditor with the 40hp program inatalled. Maybe these two problems are related. The wix fuel filter has about 3000 miles on it. Any help will be appreciated.

[gatormanpc]

Exact same thing happened to my 2007 with air intake, exhaust and programmer

[gatormanpc]

It happened again the very next day. Changed the fuel filter and reset the DCT put the programmer back on and drove the heck out of it for about an hour and seems to run fine. I drove my 2003 for 15000 miles before I changed the filter; my 2007 only had 3900 miles. Looks like I

[FBJR]

Bill, I like the setup you have there. Why the timer and so on? If it is switched on with oil pressure that should be enough. Sure a little nudge won't hurt but is it really needed?

FB

[jbplock]

FB

[FONT=Times New Roman][FONT=Verdana][SIZE=2]Your right, the one-shot timer isn't a necessity. It enables pump relay to prime the system as soon as the key is turned and runs the pump during the glow cycle. After the timer cycles the engine is running and the oil pressure switch (OPS) takes over supplying power to the pump relay. When I first installed the pump I didn