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| MAP ECU The MAP-ECU is a piggy-back fuel computer made by Performance Motor Research in NZ which uses a MAP sensor for load input and enables you to remove the Karmann Vortex airflow meter. It's quite popular in forced induction applications but the appeal to me was to be able to run individual throttle bodies. When I removed the airflow meter (below) I replaced it with a length of 90mm diameter PVC pipe which has practically no restriction.
For input the MAP-ECU primarily uses Manifold Absolute Pressure (MAP) and RPM. The pressure scale can be changed with different firmware depending on if you're running high boost, low boost or natural aspiration. You need to email them for different firmware but they are very responsive and Peter at Performance Motor research has always been quick to reply and is immensely helpful. RPM increases in 200rpm increments from 0-2000rpm which is exactly where you need fine resolution, then it increases in 500rpm increments to 8000rpm. There are 22 pressure points which results in a 374 point fuel table, plus it interpolates values in between. Instead of starting with a base map that may be nothing like what your car need, it can be wired up in auto-learn mode so it records the output of the factory airflow meter at each rpm/pressure to populate the table which makes sense as that's what it will be pretending to be. With the MAP-ECU installed and tuned and the airflow meter removed the main difference I noticed was mid-range torque. The engine definitely felt more responsive when cruising and and part throttle. It would always rev out to the rev cut easily so any change in the top end wasn't as obvious but the pressure drop through to the plenum was measured to be close to 0 over the entire rev range. Here are some of the interface screens.
It's fairly basic but that keeps it simple to use. Having some way to interpolate between points would help but you can manipulate the table data in Excel if need be - Excel's 3D graphing is way better anyway.
The MAP-ECU documentation is very good and you should read everything before you begin - RTFM! I mounted my MAP ECU next to the engine ECU and above the ABS ECU. I removed the ABS ECU from it's holder and change the holes the holder screws into so the ABS ECU is lower down which left just enough room above it for the MAP-ECU. To hold it in place I used stick-on velcro strips on the MAP-ECU and the plate it sits on so it will stay in place but can be easily removed if need be.
The plastic cover which covers the ECU's needed to have a section of the side cut out to clear the MAP-ECU. Once the cover has been fitted it still looks stock with carpet pulled back.
I'm not going to go into full detail as the documentation explains it well and has good diagrams but I've edited them to make them V8 Soarer specific.
ECU Pin-Out
Karmann Vortex Auto-Learn Mode
Karmann Vortex Normal Operation
Temp Sensor The factory air temp sensor is located in the AFM so when you remove it you need to fit the sensor which comes with the MAP-ECU. I just cut the 5 wires leading to the airflow meter and connected the new air temp sensor there. Connect new temp sensor to wires going to Pins 1 & 2 on the AFM connector
If you don't have a wideband oxygen sensor don't even bother trying to tune it - take it to a pro. If you're cluey enough to know what you're doing and you want to give it a crack yourself, you can buy a wideband O2 sensor cheaper than you may think. I bought a 2E0 unit from www.wbo2.com. It comes with a serial cable to log the output to a laptop and some free logging software can be downloaded here www.wbo2.com/sw/log.htm.
The logging software is OK but you need to take an RPM source (white wire to MAP-ECU) and plug it into the WBO2 so you can log RPM and AFR together. Alternatively you can connect the wideband output from the WBO2 (+ and -) to the MAP-ECU's O2 Sensor and Earth then log in the MAP-ECU software. This way you can log a number of things at the same time and only need the 1 piece of software. If you do want to go that way here is the O2 lookup table that the MAP-ECU software will need (Thanks to Peter at Performance Motor Research for sorting this out). Download WBO2 lookup table |
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