Hi guy's. This weekend I hooked up a friends Snap-On 2500 and went for a drive to check the intake temps at 16psi boost pulling a good hill. While I was pleased with only seeing 60deg max IAT, I noticed that my fuel rate seems quite low. It started out at around 65mm3 and slowly dropped to I think around 56-58 by the time I was at the top of the hill and I was noticing a decrease in power. I haven't done the optic bump yet and base timing was 3.4. Could it be that my lift pump is packing it in? It is a new injection pump so it should(?) be ok. Keep in mind that this is a reflashed computer too and I personally spoke to the GM tech doing the pump replacement so that he would not erase my computer and put in the stock calibration. Any ideas?

It might have gone back up to 63mm3 if you let out a little on the fuel pedal.

No that sounds like the std GM program curve you are up against, are you an S or F engine, your custom computer is by whom looks like it may need some more custom tuning if 63mm is your max, depending on how the curve was shaped that also may be playing against you. Heath, JK, & Wester have top request of 80+ mm.

All PCMs even re-flashed will cut to a lower delivery once PCM/engine needs are satisfied. Lift pump is delivering properly IMO, for if IP was starving for fuel and power was falling off delivery request would fall be for more fuel and not less to maintain power. Remember display on various scan tools is a delivery request and not actual delivery thru the IP.

The PCM was done by Turbo Technology in Washington. I'm not sure if they do it in house or if they farm it out. I still have constant 13- 14psi boost after the peaks with the vacume controls all in place for the turbo so it would seem to me that the program is still in place and wasn't put back to stock programing. I now understand the delivery request and how that works, but why the drop in power? I am lost.:help2:

Anyone?! Sorry guy's. I just have no idea what to do next.:confused:

the only thing that controls fuel rate is the PCM, the PCM cannot sense whether the pump is actually delivering the quantity it is demanding either, so you can rule IP, injectors and lift pump out completely. Sounds like you got either a poor or faulty reflash to me.

Ah crap. That was what I was afraid of, but didn't want to admit. Thanks for the input.

See if they used Z industries for the reflash which is same as BD used to sell, my experience was that it's influence was little if any over a F stock PCM, I sent mine back and finally Bill Heath came out with his, & Wester/JK then came out with theirs. Stock F PCM in a S truck is a good upgrade, only cost me $75 for salvage PCM which I needed for a core anyway, ran it for almost 2 years, until a better reflash than Z's offerings hit the street.

A number of the early 're-flash' programs merely altered the 4l80E shifting functions, with possibly some minor Boost compensation.

Try JK or Heath v2.0 reflash, which offer coordinated shift, Boost, timing, and fuel rate upgrade.

Then, the cop may tell you to try fighting the fire in the driver's seat.

LOL! Yeah, good thing I have coffee and the occasional barley soda with those guy's!;) Well, I am sure it was an early reflash because the previous owner had a Banks exhaust put on it at the same time and he showed me the stock exhaust and it looked like it should have been hanging in your local GM parts department. That would also explain the higher boost numbers. Oh, and I forgot to mention earlier that it is an F engine. Thanks alot guys for all the help, now I just have to convince the wife that the computer NEEDS to be reflashed! Hey, maybe I can still blame it on those GM guy's! Yeah, I'm sure she will buy that!:lol: