Ecu swap from 91 ej22t to 95 wrx

[chanley2010]

Whats up all, ive got my 91 legacy build coming along really nicely to the point i need a tune to continue running higher performance. I have the stock ecu in the car but was able to snag a 95 wrx ecu that was already tuned by rob with the 440 injectors. I installed the new ecu along with a jecs green maf, 440 injectors and the walbro 255 pump. The car will crank and barely idle for a second but shuts off after a few seconds. Ive been comparing the two wiring diagrams and have found only a few differences. Pins 6-7 in B58 are unused in the wrx ecu but in the ej22t ecu there is pin 7:tps shield, pin 8: maf pin 5, and pin9 is park switch. Im not sure how to use the pin 5 ecu on the wrx ecu. Also on B58, legacy ej22t computer, pin 6 is a crank shield but the wrx ecu doesnt have this??
Is there anyone who has run a wrx ecu ej20g on a legacy and if so how do i rewire this to work? Also looking for the tech guide from robs tunes because i know you have to cut one wire amd replace it with another pin. Any help is useful thanks in advanced.

[mike-tracy]

Hey Chanley, check at the top of this electrical forum for the "Electrical Compilation Thread Sticky", inside there has the info for adapting an ej20g ecu. What are you doing to convert the 95 WRX's (and also robtune) 4-channel ignition signal to run on your wasted spark setup?

The cutting of one wire (it's actually a resistor or similar) to enable the robtune (vs running the stock wrx ecu's tune) is on the ecu board itself. If your robtuned ecu is used, I would almost guarantee it is already snipped. If you really wanted to go back to the stock tune, you add a blob of solder where that connection was cut.

[chanley2010]

Im still learning the navigation through the site so that is really helpful! I was sent the ecu and a wiring diagram, however after i went through about 3 diagrams i found the one that was sent was not correct for the ecu. I found the right one and the only mismatching wire setup was the ignitions on my stock ecu set up were connector F47 pins 9 and 10 each run sylinder ignition such as pin 9 was 3/4 ignition cylinders and pin 10 was 1/2 ignition cylinders. The wrx diagrams i found had pins in 7, 8, 9 and 10 each one running a seperate cylinder which finally made me understand why my car would idle at WOT and how the robtune ignitor 4:2 works. Im in the process of either buying a converter from rob or possibly making my own? Im still learning exactly whats required for the ignitor but really think that is my problem.

[mike-tracy]

Here's the thread on how to make your own converter with a patch harness: viewtopic.php?t=37071

And here's the robtune one: viewtopic.php?f=19&t=46157

I've ran both and they function identically. The patch harness method is 3-4 times more expensive depending on where you get the harness and ignitors. I went fancy and used an SVX ignitor, though using several legacu ignitors would accomplish the same thing. Rob's ignition converter didn't exist when I went the patch harness route. I switched because I wanted a cleaner installation under the dash.

[chanley2010]

Gotcha im going to buy the robtune and install that one

[chanley2010]

Good news got a used tune till i can get the one i want and installed the ignition converter, car ran rough for a while with a small miss. I switched back ti my stock maf which seemed to make it run much better. After 1 pull car would cut fuel at 0 lbs boost. I switched back to the n/a maf green label and allowed it to boost to 7 lbs but cut after that. Found it has a rev limiter at 5000 rpm which is pretty much useless with my set up. Just gotta wait for the right tune i guess.

[mike-tracy]

Was the 5k rpm limiter when the car was stationary? How about when driving down the road?

[chanley2010]

When the car was sitting the 5 k limiter happened. When rolling the car would fuel cut at 7 lbs of boost but coukd go past 5000 rpms. Did i miss something here?

[mike-tracy]

You have discovered the tune's launch control! When the car is between 0 and 2 MPH, the revs are limited to what the original owner requested from the tuner, in this case 5k rpm. The car builds 10 psi of boost, and all you have to do is keep your foot floored on the throttle and drop the clutch!

I don't recommend you do this on pavement, because it will literally break a weakened transmission!

Anyways, 7 PSI cut is caused by a different problem besides the tune. The tune absolutely needs a JECS plastic maf to run properly. So either you have a bad maf, or massive vacuum leaks, bad sensors, bad grounds, leaking PCV system, clogged intake or intercooler, clogged fuel filter or pump or a combination of those.

Also, what spark plugs do you have, and what are they gapped to?

[chanley2010]

So i got codes 24 and 45 which is a pressure sensor code and an air control valve inop code, both would cause a fuel cut. Im going to double check the maf i have a green label maf thats black and plastic but i dont know if it says jecs. Also ive been noticing a max rpm of 4200 rpms and then a rev limiter will start to engage causing a violent rough surge.

[Legacy777]

Code 45 is more likely a culprit to cause fuel cut. Also, code 45 means it could be the pressure sensor or pressure exchange solenoid. So make sure to check both of those components.

[chanley2010]

I unplugged the maf, and drove had hesistation till higher boost levels but the fuel cut didnt occur, any way to check the pressure sensor?

[Legacy777]

http://main.experiencetherave.com/subar ... sensor.jpg

[chanley2010]

I got the jecs in and talked with rob, theres a few other issues but hopefully well overcome

[chanley2010]

I found that without the maf installed the car idles much better. However the car seems to have been stuck on 4200 rpm rev limiter excluding the launch control. With jecs maf will idle for 5-10 seconds before it just shuts off. Pre existing codes before jecs maf: 24 and 45. After the jecs installed i picked up 3 more codes : 22, 23, and 33. Any thoughts?

[chanley2010]

Update: I may have forgot to memtion the speedo was inop for a bit, however i got it working and it took away my 4200 rev limiter. Launch control is working great at 5000 rpms, but im still getting a low intermittent idle that will occasionally shut off the car and a fuel cut at 9 lbs of boost.

[Legacy777]

Reset the ECU now that you've addressed the speedo and then recheck the ECU for codes. Let us know what you find.