Hi, I have a EJ22 from a 1998 impreza outback sport engine in my 1969 vw bus. I've driven it for 55000km with no major problems. I'm having some issues now and I'm 99% sure the ecu is pooched. When I follow the diagnostic steps in the subaru manual I always get to step "replace ecu". UNLESS the IAC and TPS just aren't set correctly.
Anyway, the ECU says 'O4' on it, does anyone know what year/model car this ecu came in so I can find one and try it?
SYMPTOMS & DIAGNOSES, for those interested
For the record I have a VSS 'simulator' hooked up, basically a 555 timer circuit telling the ecu I'm cruising all the time so I don't get the rev limit at 3500 rpm.
Sometimes when starting (warm or cold) and when the rpms fall (come to stop) the engine goes into a wierd mode where it sounds like its running on 2 or 3 cylinders, a simple off/on with the key clears it up. Also when going down the highway, the engine dies at a certain interval depending on how fast you're going, 60 mph about every 10 minutes, 70 mph, about every ~6, etc. but, to get it going again all you have to do is completely let your foot off the gas and then get back on it again. If you just back off a bit it stays dead but going all the way off gets it going again. I suspect it may be a problem with the VSS since sometimes it idles very low (as if it was getting to VSS signal) and sometimes it idles at a reasonable rpm.
I just had the motor apart doing head gaskets and timing belt so no vacuum leaks, IAC is clean, I've tried other TPS's and MAFs. I get code P1507. Things I haven't tired yet are going through every wire from sensor to ECU to ensure no breaks.