ausubaru92 Posted February 13, 2006 Share Posted February 13, 2006 Im wanting to but a 88 turbo XT ecu in my 89 mpfi touring wagon along with the 88 XT motor, but will keep the mpfi loom intact. Will the turbo ecu plug straight into the existing mpfi loom or will i have to swap some pins I realise i will have to add some wires for 2 boost sensors and the Waste gate control as well as the knock sensor,... is there anything i am missing out? Any help greatly appreciated Cheers Gannon. Link to comment Share on other sites More sharing options...
ausubaru92 Posted February 15, 2006 Author Share Posted February 15, 2006 C'mon Surely somebody has done something like this before. Please, even just a yes or no Anybody:confused: Link to comment Share on other sites More sharing options...
K9WAGON Posted February 15, 2006 Share Posted February 15, 2006 I do not belive they are interchangable .. XT computers use a different plug . Im wanting to but a 88 turbo XT ecu in my 89 mpfi touring wagon along with the 88 XT motor, but will keep the mpfi loom intact. Will the turbo ecu plug straight into the existing mpfi loom or will i have to swap some pins I realise i will have to add some wires for 2 boost sensors and the Waste gate control as well as the knock sensor,... is there anything i am missing out? Any help greatly appreciated Cheers Gannon. Link to comment Share on other sites More sharing options...
ausubaru92 Posted February 17, 2006 Author Share Posted February 17, 2006 Well i have both ecu's side by side and they are exactly the same. I also have wiring diagrams for both and they are identical So i guess i will just have to try it Link to comment Share on other sites More sharing options...
idosubaru Posted February 17, 2006 Share Posted February 17, 2006 if the plugs match i believe it should work but i have no experience with that swap. i would be surprised if the plugs matched but are not compatible. Link to comment Share on other sites More sharing options...
Adam N.D.J. Posted February 17, 2006 Share Posted February 17, 2006 This is actually something that I have wanted to try out. They do look identical, and the wireing seems to be the same. Which of course there is no reason why they shouldn't be the same, as the are both MPFI, the only difference my be inside, as one has a different fuel map from the other one. Also check the harness on your N/a car, it may have the plugs in the engine bay for the missing stuff. Let us know what you come up with, as is may turn out to be uber-easy to convert an N/a MPFI to turbo'd MPFI, specially if all you have to do is swap out the computer then plug in the other little bits. Link to comment Share on other sites More sharing options...
ausubaru92 Posted February 17, 2006 Author Share Posted February 17, 2006 OK I have been given a lot of conflicting informaton But i think i have it sorted Out of the 3 FSM's i have, none of them have a dedicated mpfi wiring diagram, only turbo, so i assume that mpfi is the same as turbo, only difference that i can find is that the turbo ecu has knock sense, and wastegate control (which i believe is only an altitude compensator for lower air density) I have opened the case on both ecu's and they look identical as far as component placement goes (the only difference is that the turbo one has a second circuit board mounted about half an inch above the other one. I assume this is the knock sensing part. I have found that i do not need a boost sensor unless i have the instrument cluster with the boost light. There is no input on the 87+ ecu for this sensor, unlike the 84-86 ecus that used 2 boost sensors, 1 to turn on the boost fuel maps and one for the boost light. What i am planning to do is run a shielded wire from the engine bay to the ecu for the knock sensor, the wire for the wastegate duty solenoid, 2 wires to the dash, (in case i ever get an RX instrument cluster so i have oil pressure and boost light.) Here are some pics of the ECU's (turbo one on the left) http://www.ultimatesubaru.org/photos/showphoto.php?photo=9965&size=big&cat=500 I'm still open to any suggestions and input Cheers Gannon. Link to comment Share on other sites More sharing options...
PoorManzImpreza Posted February 18, 2006 Share Posted February 18, 2006 I'd do exactly as you suggest: "What i am planning to do is run a shielded wire from the engine bay to the ecu for the knock sensor, the wire for the wastegate duty solenoid, 2 wires to the dash, (in case i ever get an RX instrument cluster so i have oil pressure and boost light.)" as long as both ECUs are four plug you should be ok.. Link to comment Share on other sites More sharing options...
NuclearBacon Posted February 18, 2006 Share Posted February 18, 2006 yeah i'm going to agree. My knock sensor wire actually had a short in it somewhere, so i pulled the wire out of the plug and traced it back through the two engine harness plugs ect.. and the just ran a wire directly from the computer, through the firewall, and spliced it to the single wire on the knock sensor. worked perfectly. Link to comment Share on other sites More sharing options...
TROGDOR! Posted February 18, 2006 Share Posted February 18, 2006 Yes, it is plug and play, just make sure you use the right MAF and electronics setup. In the US, 1985-1987 use the older style and 1987.5-1990 use the newer style. I'm running that setup in one of my RX's right now. http://www.ultimatesubaru.org/forum/showthread.php?t=40961 Link to comment Share on other sites More sharing options...
ausubaru92 Posted February 18, 2006 Author Share Posted February 18, 2006 Ok thanks guys I the vortex xt motor i have is an 88 but has the normal l series intake but it has the serpentine belt. Since this motor didnt come with alternator, power steering pump or air con, (i will use the ones of my current car) does this mean i will have to change the water pump, or just the pulley. Gannon. Link to comment Share on other sites More sharing options...
TROGDOR! Posted February 18, 2006 Share Posted February 18, 2006 Yes, change the water pump. The shaft length is different. Link to comment Share on other sites More sharing options...
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