Getting a dip in power..

[BackyardTurbo_FTW]

Ill be attaching copies of my DAL, Max Air and TQvsRPM tables but here's the issue:

Everything is set so I should be getting 22psi and tapering to 19-20 at redline. Im not getting the full 22, Im getting about 21. It will spike and plateau for a second, then dip down slightly for a second and then pick back up and level off. The load % goes down as well as the MAF Lbs/Min.

Should I try backing down the DAL's a bit until I see a change? Am I trying for too much there?

Im also all stock, only mod is a drop-in filter. Is it possible the BPV spring isn't holding at that load?? (reaching, i know lol)

I've included a log of a 3rd and 4th gear WOT pull on the highway. You will see what Im talking about, the pull starts 450-500 timestamp.

Thanks for looking!

[oldskool]

Sorry for not being able to offer an upfront solution, but I wanted to let you know my GXP behaves the same way. The load drops with increasing RPM, and increasing the DAL values does not necessarily correspond to an increase in boost.

Some say its the stock turbo running out of breath, but I don't buy that completely. Even if the turbo is out of its effeciency range a bit, the boost pressure is still controled by the wastegate and the electronic boost solenoid. I think that piece of hardware is out of its range at ~20 PSI, and a manual boost controler is probably necessary to get the extra bump, if only for 2-4 PSI.

Of course there is also a remote possiblity that there are some more tables yet to be displayed that affect overall boost control

[BackyardTurbo_FTW]

After looking at it for awhile and trying something out just now, I think I found an answer to this. If you look at the logs, the pedal % is 100 but the actual plate is NOT there yet.

You will see the log goto 245KPa before the actual plate is at 100%. Im thinking because my DAL was 215-220 in the 90 column, it see's this as an overshoot and reduces slightly. Then as the plate hits 100%, the boost, load, power etc.. all pick back up and level off. So to combat this and test my theory, I made the 90% column 240's and the 100% 250's. I then logged the car again and IT WORKED!!! There was a split second dip, the load and all was stable this time too!!!

I plan on going a lil further in the 90% and seeing if I can't get 22psi and hold it better!

Start at 1600 in the log, sorry it was longer then it needed to be I wasn't banking on it actually working lol!

[Iam Broke]

I can't open the log files here at work, but in your 3rd run at the track, I suspected that when I looked at it last night.

I have my 80, 90 & 100% DAL columns all up higher than yours. I also have my torque limit at 100% at anything above 2k I think. If it can't reach the desired air load, it keeps trying until the throttle opens 100%.

I'll spike the MAP sensor to max 255kPa on a fast hit of WOT, but it holds at 21.5 psi through the entire pull until the turbo runs out of steam.

I had the DAL ramp in at 70%, but it caused some drivability at part load around zero boost, surged too much.

I don't think you can hold 22 psi, the turbo is too small.

Unless you have traction issues in 2nd on the HHR, I'd set the torque limit at 100% in 2nd gear. I left my 1st gear at the stock torque settings or it became smoke on command.

I couldn't open your tune last night as I'm an '08 not running the 2.23 beta. Still on 2.22

[BackyardTurbo_FTW]

Hmm, going to try higher DAL's then to get a lil more boost. I was PM'ing T2 about this as well and he said his were well above 250-255 as well.

Thanks for the input, it was helpful

[Iam Broke]

T2 helped me out a lot, I give him all the credit on my tune.

[BackyardTurbo_FTW]

I don't know him at all, but he was very helpful! BIG Thumbs up to him

[Terminator2]

I don't know him at all, but he was very helpful! BIG Thumbs up to him

Thanks guys. Part of the issue has to be the boost solenoid.The max duty cycle I ever see is 72% and that is with DALs in the low to high 300s and MALT all 100% and all torque management removed. This turbo makes peak flow at 265 kPa or 24 psi. It can make 28-30 in the midrange and hold 23-24 up top with a MBC on there. If we could set the boost solenoid DC to 100% I think tht would help out a lot. I PMed Chris about this issue.