DirtyVegasMB

I noticed after the software upgrade and even more so with the ASP in, that under very light acceleration the car shifts from 1st to 2nd very quickly with somewhat of a violent jerk... then it just starts pulling like a bat out of hell in 2nd after that. This only happens when I am very light on the throttle. Under normal or heavy acceleration this is not an issue. I just can't always be spinning tires at 50mph, so have to be easy on the throttle.
On the side note that car is an animal and I spin my 20"s with 295 rubber and put my car sideways at 50mph when ESP is disabled!

jangy

I've been noticing a similar result from my VRP and Powerchip setup. I started thinking about the pulley and the gains (boost) vs the losses (engine drag).
It makes sense that a larger pulley will also add some SC lag. The more I think about it, the more I wonder about load limits. Is the ECU shutting the power down because there is too much boost or too much load?

Can those with a large pulley and tune please post their dynos? I may do some experiments to see what is going on. I would love to see some dyno results of pulley + tune vs pulley + 80mmTB. I wonder if the TB doesn't solve the issue? It would drop pressure. It would push the shift points back up (larger compression volume). dunno...

adean1979

Has no one cracked the ECU for you guys yet so they can change fueling parameters and see what's going on? I would have thought a good tuner would have arose that could fix your problems with custom tuning.

jangy

Great point. None of the tuners were willing to do any custom work until just recently. In the past, the pulley and ECU were done at once and the customers weren't as "involved" in the tuning as now; so most never knew that they weren't getting full potential.

As of now, I know that Powerchip is aware of it and working on it. In fact, they will have my car again tomorrow to continue the tune. It has already come a long way. the top end has pretty much been openned up (too much) and it is much smoother. The shift points and load limits are still off, so that will be what they work on (I guess).

My concern is that the ECU won't be able to control the parameters that need modification. I'm leaning on thinking that some mechanical help (i.e. 80mm TB and Headers) would do some good. I hate for PC to go through all the trouble of developing this tune, knowing that I am planning on more mods (which means more tuning).

DirtyVegasMB

Well, it's not exactly a good thing that you or others are experiencing this. In the same time however, it seems to be an issue with multiple cars and various tuners. So in a way it should make you and I feel a little better that it is not our cars malfunctioning.

jangy

I've believed this all along. That is why I would never let Creative or RennTech touch my ECU until they could get the bugs out of the other three cars (which never happened). I'm doing it now because I want to mod the car heavy and a tune will just be needed. Then, when VRP and Powerchip were willing to take on the challenge, it made it a no brainer. I'm just glad to help, because I learn so much along the way.