JECS MAF Wiring - EJ20G Swap

[BoostAddict]

After modifying the EJ22T and Ej20G wiring harnesses and dropping in the Ver.1/2 Impreza STi TypeRA ECU into my 1991 Legacy Turbo, the new engine has started up, but with a few Error Codes.

The most important thing is that we're not sure about how the new JECS MAF sensor should be wired. The old EJ22T MAF sensor had 5 wires and the new JECS MAF sensor has only 4 wires...

I'd appreciate it if someone could post how the JECS MAF should be wired in to the JDM Impreza ECU.


Here are some reference pics:
-----------------------------

JECS MAF Connector:



Ver.1/2 Impreza Sti TypeRA ECU pinouts:




Thanks in advance!
Peter

[vrg3]

Aah! Dude, I asked not to have a gazillion huge pictures, but I didn't mean to ask for a few huge pictures. Shrunken images, or thumbnailed images, or links to images, would do fine.

Oh well. Let's move on.

You have the numbering of the MAF sensor pins backwards with respect to how FHI numbers them. They should be numbered 5 to 1 from left to right looking into the sensor with the locking tab on top.

With that numbering scheme, and in keeping with the wideness of this thread, here's all the info on the sensor wiring:

Code: Select all

MAF pin  Function       EJ22T wire color  EJ20G wire color  EJ22T ECU pin         EJ20G ECU pin        Notes
-------------------------------------------------------------------------------------------------------------------------------------
1        Sensor ID      Blue              Blue              B58 pin 8             B95 pin 8            missing on some JECS sensors  
2        Signal         Black             White             B48 pin 9             B43 pin 9
3        Power ground   Black/Red         Black/Red         B48 pin 11 and/or 22  B43 pin 11 and/or 22
4        Signal ground  White             Black             B48 pin 10            B43 pin 10           missing on Hitachi sensors  
5        Power supply   Red               Red               B48 pin 8             B43 pin 8

What you'll note that's interesting is that the wiring is no different between the JECS sensor and the Hitachi sensor. Yup. You don't need to change a thing from stock, as long as each pin is going through the stock path from one harness or the other.

Wow, I'm verbose. I coulda just said "leave it how it was." Sorry.

[free5ty1e]

Wow, I'm verbose. I coulda just said "leave it how it was." Sorry.

Classic.

[vrg3]

Oh, I should clarify -- the chart above is with your numbering scheme, BoostAddict, not FHI's.

[BoostAddict]

Thanks vrg3!

...I'll give this wiring setup a try early next week and hopefully the "MAF Sensor" error code will go away.

Do you also happen to know the ECU Code-Clearing proceduce for the Ver.1/2 WRX ECU that I'm now running?

P.

[vrg3]

The procedure is the same as for our stock ECUs.

[Matt Monson]

seems I don't need to answer the PM with huge pictures.

[BoostAddict]

I'm reviving this thread, since I've got my EJ20G now running correctly with the EJ20G ECU, but the MAF seems to be causing problems.

We're using a USDM green JECS MAF pictured in this thread:
http://forums.nasioc.com/forums/showthr ... ?t=1313920

With the MAF disconnected, the car idles fine and revs up to redline. When we connect the MAF, it still revs up to redline, but stalls at idle. We've got the MAF wired in correctly, because there's no CEL when it's connected (it does throw the MAF code when we disconnect it though).

We've even tried connecting the original EJ22T MAF to this EJ20G engine/ECU setup, but that won't even run.

Is the above JECS green 5-wire MAF the correct one to be using with the EJ20G engine and ECU? How do we proceed from here to resolve this idling problem?


Thanks in advance,
P.