[Powell]

Now that I've gotten a back end tune (PTF BootMod3) I have finally been able to utilize map 6, but I've been having some weird problems that seem to plague me no matter what I change. The car has a JB4+BCM, BootMod3 (HCM backend tune), and K&N Filters (with charcoal delete). It is running on 93oct with 2gal of E85. The car has almost 35k miles on it and the plugs were changed at 28.5k miles.

FUD is set to 2 for Wastegate Adaption turned off.

The car regardless of what the PID, FF, boost set point for that RPM, has a huge spike that ends up causing the car to shut the throttle body for a second to let boost come back down. I found lowering the PID sometimes kept it a little bit under control, but could never stop it from spiking enough to shut the TB down.

Then as the RPM gets above 5500 it drops boost big time (lose almost 100rwhp from peak to 7000rpm). Including an image from my JB4 Connect of what I used for Target and BIAS, and the 5500+ I would add BIAS and see no change in the logs or power loss. I figured the car would fall off some due to small turbos from the factory, but over 100rwhp drop seemed excessive (but maybe I'm wrong)



*Note* I have the factory build up for BIAS, but I have also made pulls with 0 down the board and experienced the exact same issue as well.

Quick background on Logs (I can attached Dyno sheets if need be, but they are HP vs Speed (didn't have tach signal hooked up):
Pull 4 - 686rwhp - had the most amount of drop up top
Pull 5 - 667rwhp - had a big power jump in the mid range and leveled out
Pull 6 - 665rwhp - Same as pull 5.

All the log files are done on a Dynojet 248 (non-load option either) in 4th gear (DCT) with usually about 20-30 minutes of cooldown time between runs.

I've read over Terry's thread about working with Map6 and tried to get PWM and FF close, but could never get them happy.

Checked the passenger side intercooler to TB hose and it was tight, so the thought of a boost leak is gone.

[Powell]

Also I'm currently running version 1.5 of the Firmware. Have not tried the older 1.4 version.

Edited original post, but checked for possible boost leak where the IC/TB attaches to the intake manifold and its tight as can be and looks to be sealed nicely.

[Steve @ BMS/Fuel-It!]

Loss of traction (or trans slip) will cause throttle closures.

[Russell @ BMS]

You do not regain traction until >5k rpm. I would lower the boost setpoint below this rpm until you maintain traction. You also need to raise the FF to help up top. I would raise FF from 20 to 40 and do another log. I also would reset the Duty Biases to 50.

[Powell]

I'll get some logs later tonight or tomorrow, but I figured it was possibly spinning some on the dyno on the initial hit. Just got R888's put on so it should help a lot more when I am on the dyno again.

I'll raise the FF and reset the Duty Biases back to 50.

[Powell]

Made a pull earlier (not on the dyno) and it is attached.

FF was set to 40 this time, and brought all the BIAS above 5000 to 50.

It spikes boost really hard on the initial hit, but not sure if taking the PID Higher or Lower would help stop the initial spike (looks like it closed the TB to bring boost down).

Boost seems to hold a little better up top though but still pretty far off target. PWM and FF seem to be pretty close together.

[Terry @ BMS]

Looks good overall to me. Just lower duty bias in the areas where boost is jumping over target down low but its not that bad overall.

[Powell]

So I can go below the 50 duty bias and it actually make a difference?

I was reading your thread about FF, PWM, etc. and I think I read peoples comments and understood it wrong. Basically that 0 and 50 (bias) are the same (no change) and anything between 0-50 wouldn't show change.

[Steve @ BMS/Fuel-It!]

You can run lower than 50 (like the default settings show).