Loaded my new tune but I have less power?

[JeffM]

So I bought HP Tuners to tune my C5 Corvette, everything with that went perfect. I ended up buying a 2003 GMC Sierra more recently, I've been wanting to tune it. I installed a boost valve, increased the PW 20%, boost 20%, and torque management proportionally, I also used the timing calculator to set the base timing, and modified the shift profile. So I loaded the new tune in, took it for a spin just to be disappointed. I don't have much for gauges yet but it felt like the turbo was shut right off. There is no smoke, no unusual noises, but the truck is just gutless. There is no torque to climb hills or accelerate, it feels like it just isn't fueling, so I went back to the stock tune. What am I overlooking?

Thanks in advance,
Jeff

[mecanicman]

At a glance I did not see anything wrong with the tune. The boost valve may be your issue combined with how much boost you added. Which boost valve is it and how do you have it set up?

[JeffM]

The boost valve is from PPE, it is inline from the pressure port on the compressor housing to the wastegate with the arrows pointing towards the wastegate. The valve is still installed on the truck and the truck feels much more powerful than it was, in comparison to when I had the other tune in it. Previously I had floored the truck and traffic taking off at a normal pace would pass me, the one thing I did notice was that it did seem to gain more power back as the truck warmed up. I swapped the fuel filter out thinking maybe it was getting clogged, but it didn't help. Even when the rpms jumped up there was no power, but with the stock tune everything is fine again.

[ajamesbond007]

Any check engine codes? You might want to check your High Limit Fuel Pressure parameter. You command up to 170 MPa but only allow for 167 in the parameter... granted if there is no codes, i wouldn't think this would cause an issue, but that could be why your truck feels derated....

[ajamesbond007]

Picture of parameter

[JeffM]

Good catch, although I found another item that would have never allowed more than 160 anyways. The fuel temp vs pressure was still at 160, I increased that now. I didn't see any service engine light pop on, after the big snowstorm blows through I'll load the modified program in and give it another try. I also just made a program that puts the transmission entirely back to stock, just in case that had something to do with it.

Thanks for you help guys, I'll check in again soon.