What would you all guess is the big dip at 3700rpm? And what could be causing the spikey curve the whole run? Thanx for any help!

 

Any thoughts? Please.

 

I have the exact same mods as you, except after it dips, it doesn't recover and I lose overall power.

 

I saw your post, but I couldnt see your graph to compare. Is your dip around the same spot? 3700rpm

 

Any tuners out there know?

 

Could be anything. Was it repeatable? How many times did it do it? Did you have a scanner which logged knock? Could also be slipping on the rollers during ramp-up.

 

What was the smoothing set on the dyno? Sometimes a locked converter dyno is a little jagged. On the dip at 3700 it could be just a missread from the rpm clamp that was put on your spark plug wire. Just a guess maybe someone else would know for fact.

 

I see a lot of this on our dyno and the jagged curve comes from what I can best describe as the engine not doing its job happily. We gat many cars in here that look like that before we tune them and then after they smooth out and usually pick up around 15-20WHP with the tune. I would guess it has something to do with the maps from GM, as they are all over the place if you look at them, I believe it is to give the vehicle the ability to run OK no matter where it goes (temp, altitude, Etc.), rather than making it perfect where you do most of your driving. Just thought you might be intrested.

-Bryan

 

Thanks for all the replys. Im not sure what the smoothing was set at for the dyno and the converter was unlocked unless the Predator locks it. And even when it was stock it had a dip like that. It was just a little sooner in the RPM range about 3500rpm. Now that I look at them it seems that my stock dyno numbers were the smoothest out of all three times dynoed. Thankx