archemitis Posted February 24, 2004 Share Posted February 24, 2004 i tried my damdest to get mpfi to work in my hatch, without using tens of thousands of miles of useless wires, and guage stuff i would never use. this porche dude, i have read this thing a hundred times, but i must have missed this inportant part. http://www.etischer.com/914xt.html "It took a bit of trouble shooting to get the engine to start. If I remember the efi computer got its signal from the distributer. When I hooked up only the coil to the distributer I got spark. When both the computer and coil were connected, I got injector signals, but no spark. I put a 100 ohm resistor in series with the wire to the computer, and that solved my problem ( I got both spark and fuel injection and motor started). I guess the computer put too much of a load on the distributer wire, or the computer put out a voltage to the coil that masked the distributer signal. Perhaps Im missing a diode somewhere" this is exactly what was happening to me. but now, do i dare take out a motor that runs, with a carb, to swap in mpfi with a legacy turbo and big fat fmic? does this sound right to you guys? should i put all my faith in a 100 ohm resistor? please say yes. i want a fast hatch. Quote Link to comment Share on other sites More sharing options...
archemitis Posted February 24, 2004 Author Share Posted February 24, 2004 i am confident some one that has actualy done the swap, and is still coming here will read this sometime. *bump* Quote Link to comment Share on other sites More sharing options...
TomRhere Posted February 25, 2004 Share Posted February 25, 2004 I too, am wondering on this subject. I have the wiring diagrams for the ER-27 MPFI engine. It shows a diode wired in between the circuits for the fuel pump relay, and the ignition relay. I failed to get the diode out of the XT-6 when I was scrapping it, mainly 'cause I didn't know it was there. So now I be pondering what to do. I know that a diode is a one-way gate for electrical flow, and a resistor lessens the amount of electrical flow. That may not be an exact statement, but sums it up closely. Quote Link to comment Share on other sites More sharing options...
MilesFox Posted February 26, 2004 Share Posted February 26, 2004 tom, my legacy harness lso has the diode, on the schematics it says"diode (mpfi) i think one from a turbo harness should work, might want to study up on the diodes electrical properties to make the comparison. it only connects to one wire off the ecu, then to the alt circuit fuse or relay somewhere, its a yellow wire from the alt circuit, and a green wire from the ecu Quote Link to comment Share on other sites More sharing options...
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