Engine Swap 99 into 90 Legacy! Still can't make it work! TPS

[Sh0ck3d]

I have got a serious problem. Have been working on swapping a 99 Impreza 2.2l into my 1990 Legacy 2.2l for about 8 months now. Started out very straightforward, but went south fairly rapidly. After months of sitting I am getting frustrated.

The ONLY problem with the swap has to do with the TPS. The TPS on the old motor has 4 wires, one being an "idle wire." The new motor has a 3 wire TPS, missing that idle wire. My 1990 ECU will not allow the car to run without that missing wire -- as far as I can tell. Is there ANY WAY to fool my ECU, take a TPS off another engine, ground or power this wire, etc?

The TPS sensor connects in a different way to both motors (different shape/depth connection); one is also spring loaded the other is not.

If no one knows.... Does anyone know of a shop that might be able to solve this in Seattle, WA or the surrounding area? Closer to Tacoma the better....

--

Also to note: I tried swapping the entire old intake manifold w/ TB, but this would not physically fit on the new motor.

I also tried swapping just the throttle body so I could get the old TPS on the new engine, but then I am missing sensors that are on the throttle body on the new motor. On the old legacy engine, these sensors on the throttle body are actually part of the main intake manifold, and not removable.

[vrg3]

Do you want to try the comparator thing? I can draw up a circuit for you to try.

[Matt Monson]

Yeah,
I think consulting with VRG is really your solution. I did my best at solving this my first go around with the problem...

[tris91ricer]

Pacific Import Auto is in Tacoma, as well as Frantic Four, but I don't know who all you've called yet. Could you solve this with just a new ECU?