HYPERTECH WARNING!!! for lly engines.Trip meter,fuel used,miles per gal,all off big time,Hypertech says they have just notced this problem and will accept returns through your dealer.This unit works fine on the LB7 but not LLY.Since they have different heads who knows what else might be off.My unit is in the mail back to Hypertech.Its never nice to deal with these problems,but Hpertech was very nice about it and that does help a little.

WOODMAN

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It is usually off no matter what chip you use. How far was it off?

HYPERTECH WARNING!!! for lly engines.Trip meter,fuel used,miles per gal,all off big time,Hypertech says they have just notced this problem and will accept returns through your dealer.This unit works fine on the LB7 but not LLY.Since they have different heads who knows what else might be off.My unit is in the mail back to Hypertech.Its never nice to deal with these problems,but Hpertech was very nice about it and that does help a little.

WOODMAN

.This post needs to be addressed and corrected. There is no warning or recall on any of these units. There are two different units. The older P/N, 30021 which was developed for the LB7 motor, this was replaced by the 30029 which works for all Duramax's through the LLY. The older unit will not work with the LLY.

The ONLY issue with the 30029 is the trip meter MAY be off by 2-3%. The unit has nothing to do with fuel used or MPG.

I have been on the phone with Hypertech for the last hour speaking with two of their techs. If you have a unit P/N 30021, this will not work on your LLY, there is a new unit for that, 30029 which works fine.

I have a Hypertech PP III and will have to say that the MPG is definetly off by roughly 1-2 MPG. I have only used the lowest tune so far. Haven't noticed the trip meter being off but will keep an eye on it now. I like my Hypertech.... but it did mess up the DIC MPG somewhat.

The Hypertech programmer has nothing to do with the MPG. That is simply based on miles driven/fuel used.

All programmers/chips will mess up the DIC a fair bit. The PCM is programmed with tables that determine all of these figures that you see on the DIC. Unless the algorithm is corrected with each tune, it will never be right. The chip is letting the vehicle use more fuel than the PCM knows, hence more power and a false reading.

The chip is letting the vehicle use more fuel than the PCM knows, hence more power and a false reading.
That's what I was thinking. Before the Hypertech the DIC was within .2-.3 tenths on MPG. After Hypertech it was off by 1-2 MPG. I ain't complaining though, I like the power increase and am still getting 17 city 19 highway. Compared to 13/15 on my old 2500HD 6.0L. I love Da Max!!:D

I first noticed my difference when refueling and seeing the difference between the pump and what my unit said was fuel used. My vehicle would show 17 gallons used the pump would be close to 21. I tried different pumps and also recalibrated my tire size, still the same problem. Of couse at that time my great mileage of 22.4 thru 26.2 per gallon was seriously off. I called Hypertech and talked to Gary, told him my problem and asked if he could shine any light on this subject. At that time I was told they were experiencing problems with this unit, similar to the problem they have had on certain years of their powerstroke units. I was told they did not know when or if this problem would be addressed, but that I could return this through my dealer.The unit did signifinantly improve performance. Yes this was the 30029 unit which they also use on their LB7 engine. Whereas other manufactures, like Bullydog, Diablo Sport, soon to becoming Superchip programmer, all have separate units for the LLY engine. A diesel mechanic where I work has the same vehicle as I only difference being he has the 2004 with the LB7 engine with the 30029 and no problem on his gauges. I am replacing the Hypertech with a Bulldog Power Pup programer 043567. Does anyone have imput on this unit?

WARNING .. Guess you didn't read the replies, they all do it. Don't notice any issues with mine other than the mileage will be off.