Well it's not that your missing the rear O2 sensor that's for sure. I drove mine 5 miles to the muffler shop without any O2 sensors. My guess is (and its just a guess) is you wired something important (like maybe the ECU) to your starter circuit.

 

I did double check those. I beefed them all up during the swap, so I should be good to go. I am getting 12v where I should be when key is at IG2. It's when I go to ST2 that things fire up for only a second.

Thanks man. No sig update until it drives!

I am hoping to make Martinez as well. Guess we'll see.

I have been scouring these FSM's for most of the afternoon. My head is spinning.

I think my problem might be from the circuit opening relay. There are a few differences there between the 3.4 and the 3.0. This relay also relates to the fuel pump.

It also seems like I may have the power to related engine components (injectors, coils... etc) wired in such a way that the ECM doesn't dictate when they are off and on.

Definitely getting closer... I think. Man I hope I am getting closer.

Anyone have any recommendations on a OBDII scanner or software? I have access to a laptop, although it's a few years old. I think I need to "see" what's going on, and not just get error codes. Although, error codes might be better than nothing at this point.

 

I only have four wires for the OBDII plug:

From the ECM (marked SDL).
From ground point at DS intake manifold.
From ground point at body.
7.5a power supply.

Seems the OBDII plug has pins for such things as airbags, ABS... etc.

Any guesses as to what an OBDII scanner will do without the rest of the inputs?

For those who have done the swap before, how many leads to the OBDII plug did you end up with when you were done?

 

Yeah, these work good and sometmes you'll see therm in the "for sale" section:
http://www.urdusa.com/product_info.p...s_id=840100000

https://www.yotatech.com/forums/f107/
http://www.tacomaterritory.com/forum...splay.php?f=10
http://customtacos.com/forum/forumdisplay.php?f=44
http://www.ultimateyota.com/index.ph...=26&board=49.0

 

I'm pretty sure mine only has 4.

 

Well, at least I can't be to far off.

Thanks for the OBDII links as well.

I have traced my issue down to the circuit opening relay. The 3.0 uses this relay in a very different manner than the 3.4. In fact, one is a 5 pin relay (3.0) and the other is a 4 pin relay (3.4). I am tempted to just install a standard 4 pin relay to see if that would work, but have read some relays attached to the ECM have electronic protection from spikes when the power clicks off to prevent the ECM from getting damaged.

So, just to be safe, I'll look for this 3.4 relay through salvage or even call the dealership. Who knows... maybe it will be cheap.

 

There is a relay included as part of the ORS wiring harness, but I have no idea what it does.

You're right about some relays having a diode to protect from spikes, see Quenching Diodes about halfway down this link:
http://www.bcae1.com/relays.htm

 

On my 7M swap i took the circuit opening relay out altogether and just wired the fuel pump to a switch on the dash. I think its much simpler, fewer connections to get wrong or break. I'm not sure how the 3.4 EWD looks but you can see for the 7M the EFI main is actuated by the ECU (B-O wire) which in turn actuates the COR along with other things (B-R wire), which is supposed to power the fuel pump.

http://www.cygnusx1.net/Supra/Librar...px?S=Main&P=49

So for me the EFI main only powers the ISC valve, the O2 sensor, and the +12V to the ECU, not the COR.

Short of the long, you dont HAVE to have the COR working for the rest of the stuff to function normally. IMO its overkill to have a relay dedicated just for the fuel pump.


If you try wiring the fuel pump directly and it still doesn't work I'll give you my cell # and talk the wiring over with you from my experience. Don't put the time to make it pretty, just splice in a wire to power and leave the pump running constant and start it like that. I chased demons around for months getting my electric stuff to work right, everything seems to be fine on mine now. Fuel pump stuff was part of the reason I got an adjustable FPR, so i can see exactly whats going on inside the fuel lines at all times.

I'm going home early today to try out my newly installed stock injectors, hopefully dropping the 550cc injector headache will make it run better.

 

You don't know what it does... but I assume you are using it? By that I mean to ask, this mystery relay was tied into the ORS adapter, and then you just plugged the adapter in to your harnesses. Is that correct?

That is a very helpful link. I have learned more about auto electronics during this project then I expected. Mind you, I still have a long way to go.

 

The 3.4 EWD shows the IG2 switch powering up the EFI relay. The EFI relay then sends power to the circuit opening relay which powers the fuel pump. The ECM seems to control the ground for the circuit opening relay... and in turn controls the fuel pump power.

At least... that's the conclusion I draw from this:



Where on the 3.0 the IG2 powers up the EFI relay, which in turn powers up the circuit opening relay... and then goes on to the AFM. The 3.0 circuit opening relay also powers the fuel pump.

At least... that's the conclusion I draw from this:



So, I just need to tie the FC lead (G-Y) from the 3.4 ECM to the fuel pump lead on the 3.0 (L). But if the FC on the ECM is just a ground switch, I'd need to power the fuel pump in some way... so maybe I'm back to getting the COR from a 3.4.

I may ask you to PM me your cell. I thought about wiring the fuel pump with a switch... at least for a test. Is there a problem if the fuel pump is running and the engine isn't? My guess the pump would just route the excess fuel back to the tank when the engine isn't running.

 

There is absolutely nothing wrong with the fuel pump running with the engine off, it actually is supposed to run for a half second before you crank to build up the pressure in the line. The FPR bypasses all unused fuel back to the tank. I'll study those diagrams some when i have a minute, but do try a quick hard-wire to the pump just to make sure thats not the cause of your problems. Can you normally hear the pump running at all with the engine off? It should be running in the IG position before you switch to start. My pump is external and therefore very easy to hear.

Instead of doing a switch you can also splice the fuel pump into the EFI main output which simply takes the COR out of the equation, that way its still tied to the ignition and does not require a manual switch.

 

Thanks for the response.

I am sure you are busy, and haven't really looked of the EWD's I posted yet... but I think the FC pin on the 3.4 ECM only controls the ground point of the COR. I don't think it will power up the fuel pump. Maybe I need to hard wire the 12v to the fuel pump, and then tie the FC pin to the ground for the fuel pump.

I called Toyota out of curiosity for a price on a new circuit control relay for a '96. Pretty cheap, only $330.

Almost as much as my headers.

 

Yes, it is a part of the ORS conversion harness so of course it has to be used. All I had to do was figure out some place to mount it with a screw, it was already all wired up, loomed and ready to go. Parts of the ORS harness plug into the ECU and parts plug into the body harness (and tranny in my case), its like a big multiheaded octopus that you don't dare mess with lol.

Yeah that relay link is a great learning tool.

 

OMG Reminds me of my neighbors Lexus, a headlight burned out and a replacement was over $500.

 

Thats so expensive mine 96 t100 cor was only $70 new

 

Well, I bet that relay takes the place of the 3.0 COR. Did it look like a "fancy" relay, or just your standard, run of the mill 4 point relay? I wonder if I couldn't add a diode to the ECM line side to protect form excess volts. I may make it to a salvage yard today and pic through some 4Runners... might be an easy thing to grab.

 

I'm kinda thinking the part they quoted must have been more than a relay. Maybe it was the whole junction block or something. The "tech" wasn't able to specifically find a "circuit opening relay", but evidently this part served the same purpose.

Except his part emptied the cost a lot more. Maybe Toyota designs their seats to be used only by persons with a thin wallet, so they price their parts to improve customer comfort.

 

That is how Tall Brian's 88 is setup. When I was re-doing it, I wondered what the heck that noise was, engine off key to on position. I mentioned it to him and he had heard it too.

Just saying what I heard. I have never seen that before.

 

Well... sounds like a have a few options then.

1. Hardwire the pump to a switch or through IG2.
2. Integrate the 3.4 COR with my 3.0 body harness.
3. Have the 3.4 ECM control the fuel pump directly, and eliminate related relays.

 

IIRC it was just a standard relay. Yeah, you could add a diode to any relay or you should be able to find them already made. I found a bunch of them on ebay once. They were about $4 each, they just have a diode across the back.