Rav4 3sfe to 5sfe engine swap Options

[ricochet1490]

So, I bought my first Rav4 about a month or 2 ago. I've been in the celica world for a long time and I wanted a winter beater. As it turns out, the 3s decided that it was going to start Rod knocking like a beast. Needless to say, car needed work.

I had an old 5s just sitting on a pallet in the garage collecting dust. it came from a 94 celica, and it ran when it was pulled.

Now that I've got everything out of the Rav, and from what i'm told, the 5s block will need ground on the back to make space for the transfer case, but otherwise it should be pretty straight forward I think.

I haven't had time to research everything... but to be honest there isn't much out there on this particular swap because there aren't that many gains to be had. For me the gains are purely $$$.

if you guys see anything glaring, PM me and let me know if you would....

The Plan
1) swap wiring harness from 3sfe to 5sfe
2) "depending on how the ecu works out", swap over exhaust manifold because of OBD1/OBD2 differences in the model years
3) hook tranny and T-case to 5sfe ( grind block as needed, additionally brace as needed for missing mounting points)
4) repair subframe rust, mount engine and tranny to subframe - reinstall in car
5)hook everything back up including 3sfe ecu to run engine. ** Pray ecu can deal with extra stroke/air and change fuel delivery to accomodate**
6) ** pray that i don't need to swap injectors to do this to get engine to running** - Does anyone know if there is much in the way of difference between the injectors? basically I'm looking to run the 5sfe like a stroked 3sfe. Should work I'd think.

[ricochet1490]

Ok,
So I need some help.

So it's not driving yet. turns out it hasn't been quick and simple to solve this fueling issue... And I could really use the help because it's otherwise done.
So the current fuel systems is the 1994 5sfe fuel rail and injectors, modified with the fuel pressure regulator removed off the end of the rail and replaced with the "cap" that came from the injector rail off of the old 3sfe. I did this because the regulator on the Rav is in the tank. I assumed this would be good enough as I have started and ran the car. The issue is that the car doesn't stay running for very long, like maybe 15 to 30 seconds and it shuts off.

So in trying to solve this issue, I have come up with a couple theories and have done some research. This guy had a similar problem, but never got any answers. http://www.rav4world.com/forums/85-4-1-fau...ifferences.html
But the issue is similar.

The 5s has the 23250-74100 injector


The 3s came with the 74140 injector (Could either be because of Cali emissions or the Returnless Fuel System)


On the bench


So my theories of operation are this, keeping in mind that it does run, but very shortly. When it dies it will not restart for several days really. You cant get it restarted in the same day (why I think it's fueling)

1) the 74100 injectors don't like the fuel system being set up that way as a returnless (although you would think fuel pressure should be fuel pressure) The solution here would be to make the system a return style system with the old FPR installed back on the rail running a new line to the tank. Of course removing the FPR that is currently in the tank.

2) The 74100 injectors don't like the electrical signal being given to them by the ECU (maybe a high vs low impedence thing) and will run for a moment, but not enough to sustain. Maybe there is some sort of resistor that could be soldered in? Both injectors measure the same 14.3 Ohm's of resistance however.

3) It runs for a minute and dies out because of a bad Oxygen sensor in the exhaust header. There was a bad sensor in that header that I never got replaced before the 3s crapped out. If it is sending wrong or mixed signals this could be the issue. But again, why doesn't resetting the ECU fix that issue and give me another 30 seconds of running? I don't know which sensor it is, but could figure it out or just change them both.

Are there any theories?