nitrusmr2

Hi. Long time ECU tuner, but fairly new to the Power FC.

Running a 3rd gen SW20 ECU on a 2nd Gen SW20. Fairly easy to wire up, but 3rd gen MAP sensors are over $200 used, so I set it up to use the stock 2nd gen SW20 map sensor. I used the .xls spredsheet (BIG thanks to who made that) and input a scale of 5400 and an offset of 4000. I think this is pretty close to the scale and offset of the stock FD Map sensor.

The car ran great, but the map sensor maxed out at 17 psi. I was unable to reach the top two rows of the Power FC's maps.

So I switched to using a GM 3 bar map sensor originally using a scale (6525) and offset (0) I found here. Now I was able to reach the top two cels, but I was doing so at about 21 psi.

So I dropped the scale number down to 5525. This rescaled the maps so that at 20 psi I was now in the 22000 row on the Power FC.

That seemed to work great and is 100% functional....EXCEPT the Power FC displays 1.1 bar on the commander/Datalogit instead of the actual 1.45 bar.

Is there was way to actually rescale the maps, or do I just have to live with fooling the Power FC into thinking it's running 1.1 bar when it's really 1.4 bar? Thankfully this car is not running the boost control option because I'm not sure how it would affect that.

Thanks,

Aaron
ATS Racing.net

arghx

iTrader: (3)

if your PIM ABS value was 22000, then 22000= ~14.2 * 1.2 = ~17 psi boost. 1.1 Kg/cm^2 (not BAR, 14.2 psi per kg/cm^2 vs ~14.5 psi per bar) is about right for the commander display. The PIM ABS and coordinates are not going to match up exactly to the peak boost displayed on the commander. The Advance PIM reading and Basic boost (what the commander displays) are calculated at a different time.

If you are sure your other boost gauge is accurate, your MAP sensor calibration is off. With the GM 3 bar I use scale 6630 offset 0, and I am at an altitude of about 300 feet above sea level. You may actually want to consider buying Chuck Westbrook's tuning notes (cewrx7r1 on here). After looking at the included sample map for the 3S-GTE it appears to work very similarly to the FD, except that it does not have sequential turbos, injector staging, or two timing maps. It's actually simpler to tune.

nitrusmr2

That is what I mean. I had to reduce my MAP sensor scale in order to get the full 3 bar of the GM map sensor. Otherwise the Power FC maps only used about 2.5 bar of the GM map sensor.

Let me see if I can put this a different way....

0 vacuum seems to occur at the 10000 row. That gives me 10 rows of vacuum and 10 rows boost. Is there a way to rescale that so that 0 is about 7000? that would give me 7 rows of vacuum and 13 rows of boost.

Aaron

arghx

iTrader: (3)

settings 3 MAP reference will let you adjust the scaling. but your MAP sensor is still way off. The 3S-GTE map that I have which came included with the datalogit software goes up to 26000 PIM ABS, that's almost 23psi. Were you planning to go higher than that?

You don't need to do any MAP sensor calibration trickery. If you aren't planning to go up to 3 bar absolute pressure, don't scale your map that high. For example, I only go up to 21psi on my Rx-7 but I have the 3 bar GM sensor. Why would I need cells that go up to 3 bar boost? I'm never going to go that high and i have a boost fuel cut set in the PFC. You really want to have the most resolution possible in the area of the map you plan to use. An extra 4 rows of the map devoted to pressures you never reach is a waste IMO.

Otherwise, I have seen people do P1-P10 as 1000-10000 PIM. P11-P15 goes up to 20000 PIM, and P16-P20 goes to 300000 PIM, thus you can map all the way up to 3 bar.

arghx

iTrader: (3)

Here is how I would set it up if I wanted resolution up to 3 bar. But that means you will have to interpolate/retune most of your boost cells, both fuel and timing. You are going to add a lot of work for yourself. That's why I suggest you get a decent MAP sensor calibration (try 6630 offset 0, but there are other recommended calibrations for the 3 bar on here) and leave the scaling alone unless you plan to run over 22psi (PIM 26000). I would not change the scaling of the cells in vacuum. Then you are going to have a crapload of driveability tuning to do, it will be an enormous pain in the ***.

nitrusmr2

Thanks. That is what I needed. I feel kinda dumb, I thought the PIM numbers were just arbitrary, but now I see they are basically killopascals.

I'll set my MAP sensor scale back correctly (6525 shows 0 psi with the engine off) and rescale the PIM numbers to give me resolution where I need it.

THANKS!!!

Aaron