Diablosport Forums

I finally got the time to put my truck on the dyno yesterday. I ran a run without the programmer and a run with the diablo sport tune on it. The truck is a 2003 Chevy Silverado. The Dyno showed a loss of 8 Max Torque and a loss of 20 hp what could have cause that to happen? It had 93 octane in the gas tank.

Have you done this?

http://www.diablosport.com/index.php?na ... opic&t=917

Any problem with the truck? No codes?

Truck shows no codes. Runs great it feels like its running better with the programmer on it but the dyno shows that i've lost power.

have you followed the instructions in the link? That will help.

I havent had a chance yet I'll probably have to wait to the weekend and then ill post up on here.

Sounds like bad gas may have beeb responsible for the power loss as a result of KR.

i dont think its bad gas cause it still runs great.

when did you do the baseline run? Was it that day or prior? What was the A/F ratio like for each run? You should log for KR with your predator while you are doing a dyno run. It is possible that you triggered COT on your predator runs which means that the truck richens up the a/f ratio to protect the catalytic converters and exhaust valves and consequently reduces power significantly. That is why an A/F ratio plot will reveal that. KR can also kill performance if any pinging is detected and timing is pulled.

Yup.
I say there is KR up top causing the loss of power, but the improved throttle response and timing down low are making it feel better on the street...
Figure out the KR and it should wake up.

what is KR?

Knock Retard (hereafter referred to as KR) is the response from the PCM to cylinder detonation. KR is the measure of the number of degrees of overall ignition timing advance that must be removed from the engine to prevent detonation from continuing, thus protecting the engine from damage

oh ok thanks