Rav4 3sfe to 5sfe engine swap Options

[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?

[Bitter]

30 or so cc won't make it not run, they're the same impedance, check fuel pressure.

[ricochet1490]

You thinking too much or too little?

[Bitter]

Could be either, should be around 40-50 PSI to have a running car. A little more or less than spec will still let it idle.

[ricochet1490]

Could be either, should be around 40-50 PSI to have a running car. A little more or less than spec will still let it idle.

Yeah that's what I figured too. It was a running and driving 3sfe when it was pulled. So I have to assume fuel pump/regulator have to be good enough. ****ty part is there isn't a fuel pressure gauge at my local parts store that fits imports. So it'll be a few days before I can confirm.

[njccmd2002]

why not get aftermarket fuel regulator. there are cheap prices out there to be had. even a used one.

If you are worried about an in tank regulator, check smaays v6 thread, he built and in tank pressure regulator. go back to the basics, reinstall the injectors the way it needs to be and do the in tank regulator.... if this does not work, have you tried a new ecu,

maybe ecu overheats, and then shuts, off. seen to many ecus react that way.... Triy to get a spare ECU


http://www.6gc.net/forums/index.php?showtopic=92362



that is smaays pic

[JasonTX]

i'm a little confused on the ac and injector issues? .maybe i missed something but could you not just swap oilpumps and use the 3s manifolds, fuel rail and ac compressor?

[ricochet1490]

Update.
Fuel pressure and spark timing check out. Fuel pressure holding at a constant 50psi.

Jason to answer your question, almost. The AC compressor had different plugs. And because I'm using the 3s wiring harness, I needed to swap compressor. Changed the oil pump fine. Changed the exhaust manifold fine. In hind sight I should have changed the intake manifold as well. Would have made things easier. But the injectors aren't compatible with the 5s head. So I would have had to keep those anyway.

Plugs are getting coated with fuel. Dry plugs in, no fire.

There is spark because my timing light is flashing, but maybe it isn't strong enough?
My passing theory now is that 4 months of the engine being out have meant an exposed fuel system where maybe the ethanol has attracted water and has fallen out of solution.

[Bitter]

Check compression I guess. And check spark AT the plug lead, not just the inductive pickup on the timing light.

[ricochet1490]

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.

[njccmd2002]

crank sensor light? i would check into that. make sure no short in wires, or sensor good

[ricochet1490]

So I think it has something to do with injector wiring and firing of said injectors. again, I have 3s wiring and ecu, with 5s components. I find it interesting that there seems to be all injectors on the 5s wired to both pin 12 and 25? There are bridged terminals right at the pin. Maybe I'm reading that wrong, but I don't know what to do about this now.

for anyone curious..
3sfe injector wiring using 11,12,24,25


5sfe injector wiring using only pin 12 and 25


This post has been edited by ricochet1490: Aug 19, 2016 - 6:55 PM

[Bitter]

Both look like batch fire in pairs?

[ricochet1490]

well, you just gave me something to look up. the 3s ecu is trying to fire it sequentially, 11,12,24,25, 1 pin for each injector. The 5s ecu was firing in batch, all 4 fired off of 12 and all 4 fired off of 25.

this probably is coming down now to a fuel quantity issue based on the quantity of pulses.

This is going to take some thought i think. if the injector volumes are different, then simply just splicing each injector into each output isn't the answer. I wonder if I could piggy back the 5s ecu to handle the fueling, ignition etc, and the 3s ecu to handle the rest of the car functions like tranny, gauges etc.

[ricochet1490]

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? perhaps not enough fuel to allow combustion, that eventually just builds up and causes the plugs to foul?

[Bitter]

when you get it running try to spray some carb spray into the air intake, if it smooths out a little then it is lean, if it stalls it then it's rich.

[Pez]

I was just a passer by, reading your thread. I worked in a shop specializing in toyotas and lexus for 4 years and worked on a lot of these engines. If the car runs and simply dies with no struggle (ex. no shaking, stuttering, choking) after a short time of running then i can almost gaurentee that its crank position sensor related. Check to make sure you have RPM on the tach while its running, no RPM = no crank signal, the computer runs initially off open loop where it doesn't look for crank signal, but after a short period of time it switches to closed loop and cannot run without crank signal. The check engine light for CKP confirms this. There is no need to change injectors, fuel pump, spark plugs, those things would have very diffrent symptoms. Check your wiring, your connections, and ecu pinout in relation to your CKP and i think you will find your issue. Most cars do not run long or even start with CKP problems. Best of Luck, jeff

This post has been edited by Pez: Aug 23, 2016 - 12:55 PM

[njccmd2002]

^^ posted the crank sensor idea 5 posts ago, he did not listen. lol... but maybe he checked it already

[ricochet1490]

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!

[Bitter]

Haha wow, I thought I said timing a while back?