No pulse on injectors #3 and #4, EJ20x engine, tried multiple ECUs, need help...

[Kruso]

Guys, I'm in need of some assistance. I'm working on a project with a EJ20x that was installed in a 07 base Impreza. I've done all of the work myself and had a professional remove the immobilizer off of the ECU. The problem I'm running into is that there is no injector pulse on injectors #3 and #4. I'm a controls and instrumentation engineer and have done quite a bit of work on this setup. I've traced all of the engine I/Os to the ECU, check for continuity and grounding. I'm familiar with how the injector circuit is setup within the ECU and how the grounding pulses activate the injectors using PWM. The injectors #3 and #4 are activated by the same transistor array and respectively #1 and #2 is on another transistor array within the ECU. I've verified that the controller is not sending the activating pulse at the gate of the transistor array for injectors 3 and four, meaning the ECU is deliberately not pulsing those two injectors. The only DTC registered on the ECU is P0600 which is expected since the other modules are not present in this chassis. All of the cam and crank gears are original and in great shape (no damaged teeth). I can see the crank signal going to a constant 1(??) and the cam gear signal oscillates in a discrete manner while cranking the engine in RomRaider. Timing is spot on and have spark. The engine wills start while spraying gas into the intake. I've changed out the ECU with another known good unit with identical results.

 

Recap, injectors #2 and #3 and verified to not be pulsing directly AT the ECU. For those familiar with circuits, there's no pulse at the gates of those two injector transistor arrays either narrowing it down to the controller output (used an oscilloscope to verify this) and the "collector" pin has valid ground, same ground which is shared with the injectors #1 and #2. There are numerous threads all over the internet with this issue with no known resolution. There has been reference to a "fail safe" mode which initiates this condition but I have not found any documentation which states that. I'm wondering if any of you fellas might be able to shed some light onto the matter.

 

Kruso

[mondtster]

My first thought is that you have wiring or injector problems but you say you've checked those circuits. Assuming everything is actually good, you're back to the ECU.

 

You say you had the immobilizer removed, how did you do that? I assume you had someone modify the ECU software? The software would be a common denominator and something I'd be looking at.

 

I'm curious why you're putting this much time into using a stock ECU in a non-stock application? An aftermarket controller may be easier to work with.

 

Last but not least, hello from a fellow instrumentation guy!

[Kruso]

Mondtster, thanks for replying. I had brain stormed with you towards the beginning of this venture. I had the immobilizer removed by a company, they removed the subroutine directly in the ROM which checks the eeprom for the immo code verification. I've since flashed several other ROMs onto the ECU to no avail with the help of the programmer. The programming is tried and true and is a direct two byte swap and not anything intensive. There are numerous reasons for going the stock ECU route, emissions testing being a pretty prominent one. I'm familiar with after market EMSs, I have AEM EMS my Supra but having learned the Subaru jargon, for low power goals, the stock ECU is a no brainer. There is definitely an input to the ECU which is initiating this condition. It's a matter of time before we hone in on it.

 

Kruso

 

ps... what's the deal with the layout of this forums on google chrome??

[schon]

Did you ever figure this out?? I am having the same issue with a ej20y. No fuel injector pulse on the rear two cylinders. Have replaced cam sensors, have tried multiple engine harnesses, two different ecus, have verified all grounds, checked timing, tried dozens of different maps in one of the ecu's. Still will only run like crap on the front 2 cylinders.