bigjacksauto

I know I asked this before and 2005hhrauto did a great job of explaining this .
This morning though i tried 4 times grom 60 65 and 70 mph and flooring it Does it make sense that 4 times it only boosted 15 psi? Then on the fifth try it went to 22 to 23 psi then when I tried it from a stop it boosted over 20 fine. So if I was to pull up next to say a stock ss auto on the highway the first four times it would be even then the fifth I would pull away? Not making much sense to me.
How does gm say it is making 290 hp with the gmtu if it needs a wake up call and it's boost is inconsistent.
Or is it doing something different like adding more timing when it does not boost as high to produce tje same power?

XtremeSS

I've experienced the same thing when I had my auto bigjack. Iirc when I downshifted to I or L right before putting the hammer down, it seemed to boost higher.

bigjacksauto

Thanks extreme that makes me feel better.
it's almost as if the computer says hey your in d you don't need no stinking boost lol
In d from a dig it seems fine.
I know someone posted on here that they believe that that a auto is prone to this as apposed to the stick.

bigjacksauto

Tested a few more times
in D it consistentley is making 16 psi of boost from a roll if you floor it.
if you put it in I then at times it will pull right up to 20 plus but then it seems as if the computer pulls power and slowly drops back to 16 psi
When the car is 22 plus and holding there is a huge difference in how it feels compared to the 16 so its not the case of the car making the 290 hp at 16 psi.
Read on another site where a tuner was trying to get a trifecta tune to stop pulling power on an HHR ss Auto and he said that Vince stopped emailing him.
I have Crate Engine Depot looking into this.
If I was told that the auto would make 290 hp only if I started from a stop and then made a pass that is one thing.
but to get this to hold 22 plus psi without putting it to the floor from a dead stop is not happening and I am reading more and more where that is the case.
Hope a fix for this can be found.

THE BATMAN

Went to C.E.D. This year (4th in a row) Tom and the guy that made GMTU for the SS said , After i explained , As the last engine did , it will boost too 28 psi after i clear codes , That don't show - threw the aeroforce gauges , then next pull it will boost 15 psi

Tom and the man , Said i have to buy the new plug in , but because i had the upgrade before they figured it out, I would have to buy the original wires they removed during my upgrade- At a cost of $ 300.00 and then the $ 125.00 for the new plug and play.

Am i missing somthing , Or am i being punnished for trusting in GM.

Soon to be searching for new car guy.

bigjacksauto

Batman not sure how any of that would effect your power unless wiring connections are bad?
Hope they can come through with the 290 hp. That this upgrade is supposed to produce all the time not just from a dead stop like mine is doing

foolmoon_design

Mike I would look for rubbing somewhere. Try a 40 roll it should light up the tires no problem.

bigjacksauto

I have a sticky set of bridgestones on it.

It blows away the tires in 1st but not second.
I am thinking it's Computer related since it works great when you start from a dead start all the way up.
but I will try a 40 roll
Thanks

RobSSTurbo

were you get it installed? or did you do it yourself?

bigjacksauto

Dealer installed it. It us in correct. First time they did forget to grind edge of tmap sensor.
Took it back for that and they also had to get a hold of tac (tech) to get a different tune
Since the dealer installed vacuum assist pump was not being commanded to come on.
I am pretty confident at this point that the installation was correct and after talking to other tuners it sounds. Like the gm tune is doing what it was written to do.
I am assuming during a hot day with bad air which I will see this week the boost will go back up to make up the difference?
Doubt my dealer can do anything unless they had a chassis dyno to reproduce these issues?