Possible "easy" ECU upgrade for the 91-94 Turbo EC

douglas vincent · Post by **douglas vincent** » Thu Nov 15, 2007 6:41 am

Its the JDM WRX ECU, early version, like 95-96. They use the exact same plugs, and the only thing I can find different is they use coil on plug, so the ignition out is 4 wires verus 2.

SemperGuard · Post by **SemperGuard** » Thu Nov 15, 2007 7:04 am

It's not quite that simple. I've been using an EJ20G ECM for quite a few months now, and it doesn't like the EJ22T IAC valve. It also doesn't like the stock pink injectors. Between those two things it doesn't run well. I did replace the injectors with stock G injectors, and it ran good for a while, until it lost a lot of compression on #4. As I've said before though, you need an ignitor with at least four channels to make it work. It will not work with the stock two channel ignitor.

The good part of it though is that you can use any of the G ECMs. The Legacy one I'm using is giving I think 12 psi of boost. And when it's working right it pulls hard. If you'd like to know the issues I'm having let me know.

stipro · Post by **stipro** » Thu Nov 15, 2007 7:09 am

I would like to know more about this because I can get jdm ecu's fairly easily. What other ignitor could you use that is a 4 channel, svx??

douglas vincent · Post by **douglas vincent** » Thu Nov 15, 2007 7:14 am

Well, I won't know what/why it wont work on stock ej22t myself, cause I plan on using it to run a JDM EJ20R...... So personally I shouldnt have any problems....

But checking over the pinouts of both the stock ej22t ecu and the WRX ecu, everything checked out the same.

As for the IAC, I wouldnt doubt simply switching the wires would help.

SemperGuard · Post by **SemperGuard** » Thu Nov 15, 2007 7:18 am

Switching the wires made the car not idle at all. I had the same thought as you, that since the IAC valve on G's is 180° in comparison to ours that maybe the ECM was trying to do things backwards, but switching did not help.

All_talk · Post by **All_talk** » Thu Nov 15, 2007 2:25 pm

Hmm...

The EJ20G ECU might not like the EJ22T IAC but it seems to work fine the other way, I'm running a EJ20G with it's stock IAC in my '91 SS (stock ECU) with no idle problems.

Gary

legacy92ej22t · Post by **legacy92ej22t** » Fri Nov 16, 2007 3:05 pm

The cure is to run the EJ20G heads and manifold on the EJ22T short block and then use the JDM ecu.

stipro · Post by **stipro** » Sat Nov 17, 2007 2:42 am

legacy92ej22t wrote:The cure is to run the EJ20G heads and manifold on the EJ22T short block and then use the JDM ecu.

Is it just a matter of relocating ecu pins on the stock wiring harness then??

douglas vincent · Post by **douglas vincent** » Sat Nov 17, 2007 2:43 am

I will find out, I picked up the ECU for $100. Now just have to do the swap in all my spare time that I have.

SemperGuard · Post by **SemperGuard** » Sat Nov 17, 2007 11:36 am

legacy92ej22t wrote:The cure is to run the EJ20G heads and manifold on the EJ22T short block and then use the JDM ecu.

The real cure is to buy a car that makes more power stock.

stipro
Yes you can use any ignitor that has four or more channels. EJ20G, EJ20H, EG33D. That's pretty much it I think.

You have to add two pins for the ignition and change one or two other pins I think for some sensor ground. I can't remember.

As far as what problems I was having. The engine would start fine, idle fine, and drive fine. However. Whenever I got on boost was when problems would occur. It would boost fine up to 12 psi or whatever for however long until I let off the gas and the rpms dropped into the 2000-3000 range. If the rpms didn't drop that far it was fine, or if they went below that range very quickly it was fine. Then that would happen the check engine light would come on, and the engine would feel like it was retarding timing a lot. If I came to a stop, and let the engine idle for about 30-60 seconds, or turned the AC on (be it with the AC, MAX AC, or defrost buttons), or let the clutch out enough to bring the rpms down to about 500, or let the radiator fans come on, it would return to normal. Basically whenever the load changed enough from idle. It was very strange, but I'm hoping that after I put the engine back in it will be better, found a few things that might actually make me think that it could work just slapping the ECM in, and that my problems were isolated to my engine. I will update when it all goes back together.

BXSS · Post by **BXSS** » Tue Nov 27, 2007 8:11 pm

+1 on the EJ20G not minding if it is run by a ej22t ECU, as my SS runs/idles well on that combo of parts.

It kinda makes sense that the EJ20G ecu would not like the 370cc injectors as they are small for what the ECU is used to running.

I bet the car up @ the top of the page would have run better if the base fuel pressure on the pinks was bumped up to 60psi thus turning the 370's into 434's.

stipro · Post by **stipro** » Sat Dec 15, 2007 8:26 pm

Anymore development/research on this Doug??

n2x4 · Post by **n2x4** » Sat Dec 15, 2007 8:36 pm

stipro wrote:Anymore development/research on this Doug??

Yeah, this has peaked my interest as well. I've got a VF8 in my 91SS right now, and there are 4 new 440cc greytops waiting to go in during the summer. If I switched the ECU, it should be pretty happy with that combo, right?

douglas vincent · Post by **douglas vincent** » Sat Dec 15, 2007 9:15 pm

No development. Its just sitting there for now. I have to get a turbo and uppipe still.

ciper · Post by **ciper** » Sat Dec 15, 2007 9:55 pm

I see questions about 4 channel coils,,,, why not just use 2 two channel units together? Quick and dirty sure but at least it would be easy to find.

stipro · Post by **stipro** » Sun Dec 16, 2007 1:18 am

ciper wrote:I see questions about 4 channel coils,,,, why not just use 2 two channel units together? Quick and dirty sure but at least it would be easy to find.

Hmmm.........interesting!

PhyrraM · Post by **PhyrraM** » Sun Dec 16, 2007 2:06 am

Can the ignitors be bridged together on the output side without damage to themselves or to the coilpack?

ciper · Post by **ciper** » Sun Dec 16, 2007 2:48 am

I know that they can if you use an MSD DIS unit because I plan to convert a 2 channel waste spark ECU to coil on plug.

PhyrraM · Post by **PhyrraM** » Sun Dec 16, 2007 6:07 am

I think I'm gonna research this a bit. I currently have an ej20g PowerFC to use when my ej20g goes in.

If I can use two ignitors to fire one wasted spark coil pack I can use the PowerFC on the stock ej22t.

It sure would be nice to 'practice' my tuning techiques on an expendable motor.

n2x4 · Post by **n2x4** » Wed Jan 09, 2008 2:50 pm

Wanted to bring this thread back up. I'm really thinking about doing this. Any other ideas on the whole IAC issue? Could something be done to use the legacy IAC instead of the ej20g one?

There doesn't seem like there's much needed to make this work (in theory of course)
1. 440cc injectors
2. different ignitor & change ignition pins
3. modified IAC

asc_up · Post by **asc_up** » Mon Jan 21, 2008 8:05 am

Why can't you just use the EJ20G IAC valve instead of the EJ22T IAC valve?

Wouldn't that solve the problem of the EJ20G ECU not liking the 22t IAC valve?

SemperGuard · Post by **SemperGuard** » Tue Jan 29, 2008 7:22 am

The EJ20G IAC valve has the fitting pointing down instead of up, so it wont work at all. I also had the idea of taking either the EJ20G IAC valve motor and putting it on an EJ22T IAC valve body, or just turning the EJ22T IAC valve 180° around.

Give me a week or so, and I should have the car running again. That should tell me if I was a goofball the first time or not.

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Possible "easy" ECU upgrade for the 91-94 Turbo EC

Possible "easy" ECU upgrade for the 91-94 Turbo EC