October 31, 20169 yr Mind elaborating on that? I'm using the 25D mani and harness... Why would TB and idle be an issue? You said you'd be using a '99-'02 RS harness. Those are EJ251 cars.
October 31, 20169 yr Author You said you'd be using a '99-'02 RS harness. Those are EJ251 cars. OK, wow. I really am actually an idiot. I just realized that the 99-02 cars are SOHC. Why was I thinking DOHC? I guess I thought JECS ECU in 99-02 meant different ECU which meant different heads. Nope. Same heads, different ECU. OK, I get it now. EJ25D = 96-99, one plug ECU, DOHC. EJ251 = 99-04, with two different 3 plug ECUs. 99 Forester has the 3 plug ECU with MAF. 99-02 are MAP. Matt167 is suggesting the 99 Forester ECU and SOHC heads are plug N play. Man, I really apologize for my own mistakes and stupidity. Thank you Matt167 and Numbchux for straightening me out.
October 31, 20169 yr Author Alright, I have been straightened out thanks to matt167 and Numbchux. Here's the revised plan: 93-95 Impreza wagon 5MT EJ251 longblock 3 plug ECU harness and dash from 99-02 Forester 99 Forester ECU with MAF My unknown variable at this point is the 93-95 5MT tranny and gearbox. Is it compatible with the 3 plug JECS ECU? Here are the connector terminals for the 93-95 which I have been able to find: Backup light Neutral switch Vehicle speed sensor (VSS) Starter interlock Are the 99 harness connectors plug N play? Doubtful. Two possible options: 99 sensors plugging into 93-95 tranny. Or splicing the 93-95 connectors to the 99 harness. Anybody have an answer or should I look to the junkyard for answers?
October 31, 20169 yr OK, wow. I really am actually an idiot. I just realized that the 99-02 cars are SOHC. Why was I thinking DOHC? I guess I thought JECS ECU in 99-02 meant different ECU which meant different heads. Nope. Same heads, different ECU. OK, I get it now. EJ25D = 96-99, one plug ECU, DOHC. EJ251 = 99-04, with two different 3 plug ECUs. 99 Forester has the 3 plug ECU with MAF. 99-02 are MAP. Matt167 is suggesting the 99 Forester ECU and SOHC heads are plug N play. Man, I really apologize for my own mistakes and stupidity. Thank you Matt167 and Numbchux for straightening me out. To clarify. EJ25D in an Impreza/Forester chassis was 1998 only, 1996-99 in the Legacy. EJ251s started in 1999 in the Imprezas and Foresters, and 2000 in the Legacies. And went through mid-year 2005. I know that all 1995-1999 Legacies use the same ECU connector (although 1995 was pinned differently). I know the EJ22 Imprezas through '99 were the same, I do not know about the 2.5 cars. Manual transmission stuff is easy. If it doesn't plug-in, splice the connectors, it's only a handful of wires. Starter interlock is on the clutch pedal for a manual. Only thing to be aware of, is as of about 1995-96, they switched from a cable speedometer to electric. If you're running an electric speedo cluster with a transmission that was originally a cable, you can un-thread the cable from the transmission case, and thread in a sensor from a late-'90s car. Off the top of my head, I think they are 3 wire, 12v+, ground, and signal, so you'll want to grab the connector from a yard or your donor car.
October 31, 20169 yr Author If the manual transmission sensors on the 93-95MY Imprezas can all be threaded/spliced to the 99-02 three plug harness, that wraps things up for me. Basically, all I need to know is that I don't have to do a tranny/gearbox/clutch swap. I intend to keep the drivetrain exactly the same, don't want to spend a dime on it for 165HP.Everything on the engine side will match up with the full harness swap. The headlights/taillights may be a PITA but should work out. Dash, cluster, and ignition switch will be fully swapped from 99+. Dash back is pretty irrelevant. Front harness, fan switch, and fuseboxes may be a PITA but I think it will work out.That's pretty much all I need to know, think that just about wraps things up for me here. Unless anyone else wants to chime in then I'm moving forward from the planning stage to the acquisition stage of the project. A huge thank you for all the helpful info. Edited October 31, 20169 yr by janas19
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