Hi. MR2 guy again. Sorry, but this is still the best place for Power FC information.

I've been running on the stock gen 3 MR2 map sensor (2.9 bar sensor) for a couple months now. I have boost levels set for 1.25, 1.45, 1.7 and 1.9 bar. Everything worked great until yesterday.

I installed a 4 bar map sensor (it's actually a gauge sender for a new MSD boost gauge) but it's 0-5V so it works. I used the .xls spreadsheet program I found here to calculate my correct scale and offset. The scale I needed was actually larger than the Datalogit/PFC would accept so I had to compromise. I am using Scale 9830 and offset 3600. It's pretty close. It's off by about 1.5 psi at 0 psi and read the vacuum a little low, but it's dead on accurate at 1 bar and less than 1 psi off at 2 bar of boost.

After some shuffling around of fuel/timing maps to give me more resolution above 1.4 bar of boost it fired up and ran great.

But now my 1.25 bar boost controller setting hits 1.7 bar up to about 6000 rpm and then falls back to 1.3.

Turning the boost control option off on the PFC actually SHUTS the boost control solenoid so that creates an even larger boost spike (I think I saw 2.1 bar on the gauge before I quickly let off). So I know that the boost control is sort of working because I get less boost with it on...but why is it spiking up so much with just a MAP sensor change?

Thanks,

Aaron

 

What boost controller are you using ? This is the PFC boost kit right?

Is it an internally or externally wastegated turbo? Do you have the solenoid configured correctly (NC vs NO port if it's a Denso solenoid used in Apex'i and Greddy products)?

It's funny you mention how weird the PFC boost control is in relation to the MAP sensor. On my friend's FD which I have tuned, he has stock sequential twins with OEM boost control solenoids. The boost is set to 1.0 K/cm^2 , so around 14psi. He has the stock, inaccurate MAP sensor calibration with the OEM sensor. I didn't change it because I didn't want to have to retune the whole car, too much trouble when it was already running right based on my logs.

So while the PFC boost reading is more like .85 k/cm^2 the peak boost on the mechanical boost gauge is a consistent 14-14.5 psi, right where it was set in the PFC. Weird huh? I've considered changing the MAP sensor calibration but the car runs well enough right now that it would just make more work for myself for no real benefit. I already adjusted the fuel and timing curves to compensate for the inaccurate boost reading.

 

I played with it some more today, apparently when I entered the new scale and offset for the 4 bar map sensor the boost control part of the PFC just ignores that..that's why I wasn't getting fuel/boost cut either.

So I ended up dropping my boost setting to .5 bar so that it will run 1.4 bar.

Aaron

 

Another reason to buy a REAL boost controller.