Parameters 5 and 7

[vin7]

Eric,
Can you describe what areas of the boost curve are influenced by parameters 5 and 7? With parameter 5 set to 100 I get a boost spike to 22-23psi and it tapers off. I adjusted this to 74 and now I get a steep slope up to 17 and you can see the curve level off at 18psi (on the monitor you can observe the wg duty cycle drop down at WOT to about 70 and then starts (stair step pattern) to work back up to 100 during the spool up (rolling start at around 10mph, starts in 1st, shifts to 2nd). It seems to hold 18psi steady, but at the 2-3 shift wg duty cycle changes to 85 and boost increases and holds at 19.5psi.

With that in mind, can you walk me through how changes in these two parameters are working to form the boost curve? At what point does parameter 7 take over to control max target boost?

 

[EricM]

I assume you mean param 5 and 6. (7 is wideband AFR)

When not in boost (under 0 psi), the wastegate solenoid is commanded to 100% dc. When you get on the gas, and you hit about 0psi, the dc will drop to around 70% initially, but parameter 5 can modify that. That is your initial dc, which affects spoolup. Once you hit about 7psi boost, it changes to closed loop control, and will step the dc up or down to try to hit your target boost.

There is a "reset" that happens on a shift (up or down), where the dc will go to around 70-90 dc depending on the chip programming, then back to closed loop. That is not adjustable by the user. I can reprogram the chip to change that if necessary.