legacycentral bbs

Hey hey.

Just got a pair of what are supposed to be N/A ECUs for their connectors and am puzzled upon taking the first one apart:



What the fork is that?? There's a hole on the back of this ECU where this thing is aimed. The entire circuitboard's sole purpose appears to be driving this thing, which I suspect is some sort of pressure sensor.

Did some Legacy ECUs use a board-mounted atmospheric sensor instead of sharing the MAP sensor under the hood? The other N/A ECU I have here does not appear to have this strange piece of aircraft-grade technology.

The sensor itself is a thick film hybrid microcircuit - on the exposed thick film (on the top) I can see laser-trimmed resistors. Highly accurate stuff. Overkill, in fact - which does agree with Subaru's engineering practices.

Anyone know for sure what this is and what it's for?

Non-turbos up through 92 had that kind of onboard barometric pressure sensor.

Never seen inside the ECU before. Pretty cool. That's not too complicated - we design stuff more complicated than that all the time. But, it is surprising to see so many surface-mount chips from what's basically an 80's design.

Well, JECS ECUs like this one are of a newer design than the 80s-ish Hitachi ones. It's more of a 90s design. This same basic ECU was used up through like 96 or something overseas.

Hey Freestyle -

You're just poaching connectors, right? Mind sending me the circuit board when you're done abusing it?

Thanks - I couldn't imagine what else that thing could have been used for. So pre-facelift N/A ECUs have this onboard sensor? Interesting.

All turbos had the under-hood atmospheric pressure sense, correct?

Rallysam - I am mostly poaching connectors, yes. Not sure if I will end up using or experimenting with any other parts of the ECU, but if I don't you'd be welcome to the internals. It may be a couple months though, because of the move. Right now I'm just planning for the next LegacEBC circuitboard while I've got a little breathing room with my paid work.

Not just pre-facelifts -- 92 models also.

Yes, all turbos used the pressure exchange solenoid to allow the underhood pressure sensor to measure both manifold pressure and atmospheric pressure.

By the by, there were so many high-quality useful components on the ECU boards, I'm not sure you'd want what's left... we stripped the hell out of them.