keithbrents

Ok so I did a rebuild on my 94 22re..I didn't do a great job labeling plugs and what not..so my question is are the fuel injectors assigned to a certain plug or does it matter

Sorry in advance if it's been covered, I did a lazy search with no luck

Terrys87

iTrader: (1)

The Injectors can go in any cylinder you want, the electrical connectors have to go to the correct cylinder. The way the harness is set up, it is almost impossible to get the connector on the wrong cylinder.

scope103

Actually, the injectors all open at the same time; they are not synchronized to the individual cylinders. http://www.cygnusx1.net/Media/Supra/...taTech/h22.pdf So while it is difficult to hook them up in a different order (as Terrys87 points out) , you can if you want and it will still run fine.

It's a curious setup, but Toyota uses this same setup on lots of different engines.

keithbrents

Thanks Terry87..I'm pretty sure they are correct, I started thinking about it after I got them connected. Thanks again

keithbrents

And thank you Scope..that gives me even more piece of mind!!

Terrys87

iTrader: (1)

Thanks Scope... I have often wondered about the way Toyota does their injection system. Looks to me like it would fire the injectors on all 4 strokes of the motor and would put raw fuel on the Exhaust stroke, there by dumping raw fuel into the exhaust system. Maybe it does not do that, but the way Toyota has 2 injectors sharing the same circuit as on Pins #10 and #20. I am guessing the 3.0 has 3 injectors on one Pin. It works how they have it, just dont fully understand how.

scope103

The fuel won't dump directly into the exhaust system no matter when the injector opens. The injector is on the atmosphere side of the intake valve, and the fuel can only enter the cylinder when that valve opens on the intake stroke. For what it's worth, the diagram in the link I posted shows the injectors (all of them) opening once per crank revolution, or only on 2 of four strokes. So half of the cylinders get additional fuel on the intake stroke (plus some more on the power stroke, that just sits there), and the other half get it on the exhaust stroke and have to wait a bit for the intake valve to open.

I have no idea why it's done this way (my guess is the limited processing power of '80s vintage ECMs). But it's worth remembering that liquid fuel won't burn. It has to evaporate. The big reason fuel injection is so superior to carburetion is that the fuel is sprayed through a ~40psi pressure drop, rather than dribbled through a 2-3psi pressure drop. The better atomization allows the fuel to evaporate more quickly, rather than coating the inside of the intake manifold for a bunch of milliseconds. Having the fuel vapor "hang out" in the intake manifold for a tiny bit probably doesn't hurt at all.

Terrys87

iTrader: (1)

That does make a lot more sense to me . Basically it is hanging out in the Intake until the valve opens and pulls the mixture in so as when the injector is firing really does not depend on which stroke it is on. Pulses are small enough to have enough mixture sitting in the Intake ready to go and waiting on the valve. Thanks.

wallytoo

iTrader: (1)

this feature allows one to test whether a single injector isn't firing by switching connectors. if the problem remains at the same cylinder/injector, you've narrowed the search. if switching moves the problem to a different cylinder/injector, the problem is probably in the wiring between the splice and the connector.