MoTeC Global Forum

I will soon be starting an installation of a WRX9-10 plug-in board onto a USDM 06MY STI. I have already designed a patch loom for this to be a plug-in affair.

Due to a few sensor changes, I was wondering if anyone (MoTeC?) could provide the 2.0 EJ207 (JDM) base map for the WRX7-8 board (the one that includes spray bar control w/AV8 IAT sensor input), as well as a 2.5 EJ257 (EDM) base map for the WRX9-10. I think I have the latter file, but want to make sure I'm working from the most recent revision.

The reason I need these maps is I am currently using an intake manifold and injectors from an EJ207. I will be copying the following calibration data from the EJ207 base map to EJ257 base map:

Second IAT sensor - should be set to AV8 in base map
~550cc EJ207 (pink) injectors

The injector size of the EJ207 injectors is similar to the EDM blue injectors, but the latency is considerably different. For the IAT sensor - the secondary below the throttle will become the primary using a patch loom placed in-line to MAF sensor (for more accurate, post-throttle IAT data).

USDM and JDM/EDM wiring is different

Also your crank/cam configurations could be very different too

USDM got DBW earlier than the JDM/EDM models. Not sure what years changed the cam/vvt signals on US models, but the JDM/EDM could well still be using the front cam phase sensor and 2 rear VVT sensors

Could be quite a lot of differences.

You are correct, which is why I am using the WRX9-10 board rather than the WRX7-8.

The USDM 06+ WRX and USDM 07+ STI are nearly identical in wiring to the 08+ (and 06-07 2.5L EDM) models that the WRX9-10 was designed for. As I mentioned - I have designed a patch loom to connect the WRX9-10 to a 2006 USDM STI.

The cam/crank configuration on the 2004+ USDM STI is the same as the 2008 configuration the WRX9-10 is designed around (2 cam sensors, 1 dual-signal crank sensor). Exhaust cam control is obviously going to be omitted, as this didn't come into play until 2008. Since the WRX9-10 is designed to control an EDM 06-07 2.5L car (with intake-only variable cam control), this is not a problem.

In terms of wiring, WRX9-10 works for the following USDM cars:

04-06 STI - major wiring concerns (patch loom required)

07 STI - minor wiring concerns (differences in grounds, primarily)
06-07 WRX - minor wiring concerns (differences in grounds, primarily)

08+ cars (in general) - more-or-less plug-and-play (didn't research extensively)

To summarize - I've already worked out the differences between models, and now I'm at the point where I need base maps to mix/match the sensor settings to match my car.

With the wiring issues already worked out, my system is now VERY similar to the 2006-2007 EDM models, with the caveat that I am using a post-throttle IAT sensor and injectors from an EJ207 car; hence the need for WRX7-8 base maps.

I've ordered a second IAT sensor out of Japan to test the resistance/temperature curve and the injector latency can be sorted out during tuning... but it would be a lot easier to just get the data direct from the base map.

Got the IAT (i.e. ACT) sorted by testing the resistance curve from 10-100 deg C - the default Bosch 2500ohm sensor is pretty close from 10-40 deg C, then deviates. The STi GpN ROM provided the following values which more closely match test values at higher temperatures that will be common, post-turbo:

Temp (C) Voltage (V)
119.9975586 0.21
119.9975586 0.36
119.9975586 0.52
108.7670898 0.67
98.81347656 0.83
90.44189453 0.99
83.34228516 1.14
77.24121094 1.30
71.89208984 1.46
67.09228516 1.61
62.66601563 1.77
58.48144531 1.92
54.43847656 2.08
50.46875000 2.24
46.52832031 2.39
42.60742188 2.55
38.69873047 2.71
34.81201172 2.86
30.95703125 3.02
27.13134766 3.17
23.31298828 3.33
19.44091797 3.49
15.41259766 3.64
11.06201172 3.80
6.142578125 3.96
0.310058594 4.11
-6.889648438 4.27
-16.04492188 4.42
-27.90771484 4.58
-40.00000000 4.74

Injector latency was pulled from the JDM ROM (OEM and GpN) image(s) as:

Voltage Latency (OEM) Latency (GpN)
6.5 V 2.788 ms 2.86 ms
9.0 V 1.488 ms 1.56 ms
11.5 V 0.980 ms 1.05 ms
14.0 V 0.684 ms 0.75 ms
16.5 V 0.380 ms 0.45 ms

I believe the GpN ROM may have had a little extra time spent calibrating the sensors when compared to the OEM ECU - the IAT/ACT sensor is definitely more accurate, and the latency is just an across-the-board increase of 0.07 ms. While it doesn't matter as much with the M800, the flow constant was also changed from 552.47 cc (OEM) to 575.61 cc (GpN) which is more in-line with real world flow testing (565-570 cc).

Hi mrsaturn,

is the data you've posted valid for a 2004 STi?

Thanks in advance

Be a little more specific - 2004 USDM STi?

The data posted was for JDM GDB Spec C pink, top-feed injectors, and the auxiliary IAT sensor beneath the cable throttle (again, on the Spec C, only).

Should be a 2005 JDM STi Engine in a 2004 EUDM Chassis. I've checked a lot of roms and the IAT cal always looks like the table you've posted, but i'm not 100% positive if it represents the additional Sensor before the TB from the SpecC or the IAT/MAF on a "regular" STi. Denso Part Number is 22680-AA310.

Thanks in advance

Values posted from the GpN ROM are for the IAT under the throttle. The GpN ECU converted the car to speed density, and the IAT allowed for this. I also resistance tested the auxiliary IAT sensor and found it to most closely match the resistance curve in the GpN ROM.

As I see it, the IAT near the throttle did two things:

1. Allowed the homologated engine to switch to speed density.
2. Allowed the factory ECU to control the I/C auto spray as a means to stabilize the IAT.