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1997 3sfe to 5sfe Swap

32K views 40 replies 11 participants last post by  superkel 
#1 ·
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.

From my years in the celica game 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.
 

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#2 · (Edited)
here we are. Wiring harness is swapped over mostly sucessfully. I've been notified of a potential crank/cam sensor issue between a 94 5s and a 97 3s.... illustrations below.

Issue #1 - AC compressor plugs are different. Maybe can swap over 3s compressor? Don't know yet, need to investigate.


Issue #2 - Random plug available, not used on 5s, used on 3sfe. - This is likely the aforementioned Crank sensor


The wiring on the other side of that for the 3sfe goes down beside the crank pulley. this COULD be an issue. We'll see, but I don't know what it is.


There are some other harness length differences, but everything does plug up, it's just a little more stretched than it was before.

If I have to use the 5s ecu, I wonder how that would affect the transmission part of this car given that it's an automatic and I think the ECU has a hand in controlling that mess.

All unknowns, nothing unsolvable I don't think though. Curious that the 3sfe might have a crank position sensor though
 
#4 ·
That wiring down to crank pulley is for the crank position sensor, without this connected the rav's ecu wont be able to run the engine i wouldnt of thought, can you retro fit the sensor and timing plate etc maybe ?, i cant remember what's behind the bottom pulley for sensor to pick up on but normally there is something there for it to get the cranks position
 
#7 ·
So I've got everything sorted I think. As you can see here, the crank position sensor runs off the timing sprocket with the sensor integrated into the oil pump. Everything else had already swapped over and plugged up.


So, tonight with any luck I'll have the obd1 5s oil pump removed, the one from the 3sfe swapped in, and the oil pan back on. After that I'll swap over the AC compressor and begin trying to mount the 5s to the awd gear box, grinding the block where I need to to make it fit. Then a swap of exhaust manifold somewhere there to make sure I get that oxygen sensor... I think it'll work.

The only thing that'll stop me now is if the 3sfe ecu doesn't have enough fuel map to run the 5s because of the extra stroke. But I'd sure hope it would. We'll see what happens I guess.
 
#13 ·
it does now!

I actually have a fuel pressure issue with the fuel rail. The one on the 5s was a return system and the one from the rav was returnless I found. But that should be quick and simple and it should be back on the road this weekend or next. I'll have to give it a good shake down because I had to do a lot of "repairs" along the way. But I'm confident it'll all work out.
 
#14 ·
Ok,
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-faults-fixes/138233-1998-3s-fe-head-injector-differences.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?
 
#15 ·
Could it be in the fuel pump control circuit?
The ECM controls the Rav4 fuel pump. When the ECM sees the starter being active it turns on the circuit opening relay for several seconds, then the ECM looks for the NE signal from the crankshaft position sensor.
After the ECM sees the NE signal, it keeps the fuel pump on until the NE signal stops.
 
#16 ·
OK, so it now kind of runs, but still dies. I put straight fuel injector cleaner in the fuel line after the fuel filter and it is now restarting in the same day with some time between start attempts, but only barely idles and doesn't rev hardly. I do have a crank position sensor check engine light, but don't know why that would make it choke and die. It'll "idle" longer if I have my foot to the floor, but that's about it.

I'm right now thinking that either the injectors aren't working right with respect to fuel atomization, or they are flat not going to work because they might be spraying too much fuel. Perhaps the 5s injectors are totally different than the 3s injectors?

definitely getting closer.
 
#17 ·
I have been following your adventure with this transplant because I own a low mileage 5S-FE out of a 95 Camry I use to own. I also have the 94 Toyota Camry service manual because it was free and was usually close to my 95 Camry.

The 94 manual claims the California version of the 5S-Fe used the ECU pins #10, #20, #30, and #40 to fire the injectors, like my 99 Rav4 does.

But the non-California version does it differently, using pin #10 to fire injectors 1 and 3. While pin #20 fires injectors 2 and 4.

The manual does not say why, just the wire drawing showing the 2 pin-outs, Cal and non-cal.
 
#18 ·
I have a 1994 celica haynes manual showing injectors firing off of pin 12 and 25. The haynes manual for the 97 rav4 with the 3sfe shows that each injector has its own output. Pins 11,12,24, and 25. Very interesting indeed how that ended up.

i wonder how to fix this... This must mean that in the 5s it was expecting injectors to fire multiple times. But even with that said, those wires cross too. it's almost as if the duty cycle on the injectors is different, requiring different ECU signals.

Perhaps now that I have a 3s ecu trying to run the 5s, I should jumper each injector to each output to get the correct number of pulses? I'll be honest, I'm not really sure.

Or perhaps put 1 and 3 on pin 12 and 2 and 4 on pin 25 like the 5s wiring diagram says....
 
#20 ·
At first I would think that you are seeing the difference of batch firing injectors and/or sequential injectors. BUT given the pin wiring colors, I would wonder if they are both batch fire ecu with completely different injector drivers in the ecu? Either way, I would match the ecu and engine if possible.
 
#22 ·
this got me thinking a lot and doing some more looking. I think it looks like the 3s is a sequential injection, the 5s as a batch injection. But the more I've researched today it shouldn't really matter if it's sequential or batch fire if the quantity of fuel is the same. and this is where it gets weird.
Everything here says not enough fuel.
Larger engine 2.0 -> 2.2L, so 50cc additional air volume per cylinder
Smaller injectors, computer is set to run a pulse width for a 250cc injector, the 5s injectors are 220cc. when you do the relationship simple math of injector size vs displacement and assuming the same pulse width, I need 20% more fuel than what I'm getting today to make stoich.

But when I pull the plugs, they are coated black and smell of fuel because it's not firing and when it does run the tail pipe smells rich.

so which is it? Not enough fuel or too much? perhaps not enough fuel to allow combustion, that eventually just builds up and causes the plugs to foul?

In which case it seems the easiest thing to do to match the 3sfe ecu pulse width would be to find a similar injector, that fits the hole, that has the same resistance, and a volume of closer to 250-275cc. Effectively get the right ratio of cylinder displacement to injector size to match what was factory.

Thoughts?
 
#21 ·
I think your 5sfe drawing has an extra wire that doesn't belong, it is not on the ones I have here.
Firing the injectors in pairs makes a little sense but all 4 would not work.
With the 1-3-4-2 firing order #1 would be at the top of the compression stroke and #3 would be just starting its compression stroke when the injectors fired as will #4 and #2 in their turn.
Maybe 2 and 3 get better fuel distribution from the early injection.

I think you are trying to use the 3s-fe ecu.
If so, to pair up the injectors you will need some to add some resistors.
 
#24 ·
Well, it runs and drives!

As it turns out, it really is that easy. The 5s will run on the 3s wiring and ECU.

None of the things that we were talking about ended up being an issue. The issue was that the engine had skipped time when I first started it up after I installed it and I didn't know it.
Compression test yielded a 50psi result and when inspected the belt was about 4 teeth off. The tensioner spring was weak and couldn't keep tension on the belt. Now that we have a new spring installed and the timing issue resolved it purrs like a kitten.

I have a vacuum leak somewhere, it's idling a little high. But a trip around the neighborhood and all is well.

thank-you to everyone who provided insight and information!
 
#41 ·
Well, it runs and drives!

As it turns out, it really is that easy. The 5s will run on the 3s wiring and ECU.

None of the things that we were talking about ended up being an issue. The issue was that the engine had skipped time when I first started it up after I installed it and I didn't know it.
Compression test yielded a 50psi result and when inspected the belt was about 4 teeth off. The tensioner spring was weak and couldn't keep tension on the belt. Now that we have a new spring installed and the timing issue resolved it purrs like a kitten.

I have a vacuum leak somewhere, it's idling a little high. But a trip around the neighborhood and all is well.

thank-you to everyone who provided insight and information!

Can i add to your headache?. i am in australia. i have a 96 rav4 manual, but i now have a 5sfe out of a 91 cilica. just what do i need to do to make this conversion work.......reading all the posts is getting confussing to me. any help wpould be appreciated.

kel.
 
#25 ·
How is the 5S doing in your Rav4?

How is the power and fuel mileage?

That is great news that it will run with the 3S ECU and wiring harness.
 
#26 ·
5s is running good! I actually like the torque better than in the 3s.
If I ever did it again, I would use the 3s intake manifold. That's been the biggest issue is making all that work.

Fuel economy isn't bad. With it out of alignment and the tranny showing a P0770? I think it is, (torque converter not locking up), I'm getting 23 or 24mpg. So should be better when I solve that tranny issue. Car needed major maintenance when I bought it...
 
#27 ·
If I ever install my 5s, I would want it to look like a 3s. Using the 3s intake it would no longer announce it is 2200cc, a bonus in my book. And while I would really like a little more torque, like you said this swap only makes sense if you already have a 5s.
My 3s has 190,000 miles on it and I've had it for the last 30,000 miles.
My 5s has 135,016 miles on it, but I've owned and pampered it, for the last 60,000 miles.

I really like my Rav4 and hope you have a lot of fun with yours.
Thanks for all the information!
 
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