Error in TSRM on page FI-50?

[Steven]

Is it possible the Toyota Service and Repair manual has a booboo? It's my Bible and I'm starting to lose faith....and I'm getting very confused tracing my present injection problem.

The injector pairing on the ECU outputs, as shown on FI-50, does not match the pairing shown on wiring diagram page 8. These are both for 7MGTE ie. turbo.

My hardcopy manual says exactly the same as the Cygnus X1 online manual, so no help there. Maybe there has been a factory error note issued...anyone know?

On FI-50 it shows ECU pin 10 going to injectors 1, 6; then ECU pin 20 to injectors 2,3; then ECU pin 30 going to injectors 4, 5.

On Wiring Appendix p8, it shows Pin 10: 1,4; then Pin 20: 2,6; then Pin 30: 3, 5.

If the firing order (as given on TSRM EM-3) is 1-5-3-6-2-4 then the FI-50 page makes nonsense in terms of injection sequence, but the wiring diagram makes sense - the way that the wiring diagram shows it, pairs of cylinders immediately adjacent in firing sequence get the squirt together.

Anybody have some firsthand info on this? Thanks!

 

[shaeff]

here's how i have my injectors wired, if that's what you're looking for-

1 & 4 are the same colors - (yellow and white/blue)
2 & 5 are the same - (black and white/red)
3 & 6 are the same - (white and red)

the pairs can be switched, like between 1 and 4, 2 and 5, and 3 and 6.

-shaeff

 

[suprarich]

here's how i have my injectors wired, if that's what you're looking for-

1 & 4 are the same colors - (yellow and white/blue)
2 & 5 are the same - (black and white/red)
3 & 6 are the same - (white and red)

the pairs can be switched, like between 1 and 4, 2 and 5, and 3 and 6.

-shaeff

Shaeff- that needs to be in the FAQ as a sticky because in the last 3 months I think I have answered that exact same wiring order like 10 times to various folks.

 

[Steven]

Oh Lordy! Shaef, Suprarich, thanks, but this gets worse and worse...

The injectors as I found them on my engine were exactly as Shaef listed them. Both wiring diagrams in the manual say our observed order is wrong, though they don't agree with each other... or our observed wiring.

The reason the observed order on my car (and now yours) looks wrong to me is two of the injector pairs squirt into adjacent cylinders in the firing sequence but one (the 2,5 pair) does not. Shouldn't the sequence be the same for all pairs?

The way the wiring diagram in Appendix p8 has it, all pairs DO squirt to adjacently fired cylinders.

I have to ask, "Does it matter?" Some engine fueling systems fire all injectors together, once a revolution. Or so I recall. Maybe any cylinder doesn't care where in the cycle it is injected? It all gets gulped anyway....

I haven't put the scope on the Supra to see if they all fire together or whether they are sequenced. I can't recall anything in the manual about either case. Certainly the general setup of wiring is consistent with a sequenced injection.

I tried switching injector harness to 5 and 6 so that I match the Appendix p8, but I can't tell if it runs better or worse.

This is because I seem to have a dead ECU output on pin 20, so it's running on four cylinders no matter what. Which is the present result of my labors, and the whole reason I have been sorting through all this crap in the manual instead of doing my Christmas shopping.

I'm now trying to source a used ECU for this 1990 Turbo. Suggestions are welcome for that too.

Sorry for raising three issues in one post.

 

[3p141592654]

Are you sure its the ECU? If you had an open circuit or broken wire in one of the three EFI resistor networks in series with the injectors then you would also get a dead injector bank.

Maybe you already tested it, but with the ignition on, you should see 12V on the red, black, and yellow wires at the injectors. If you don't, then look at the EFI resistor pack and wiring.

http://www.cygnusx1.net/supra/Library/TEWD/MK3/manual.aspx?Section=Main&Page=46

 

[chriso]

Oh Lordy here also....I wired mine exactly how the TSRM shows a few months back when I was having trouble starting a fresh rebuild. I labeled the plugs exactly as I had taken them off of the old engine and then put them back on my new engine the same way. I thought I had a couple of the plugs switched due to my idling issues. When I looked through the TSRM I discovered the "mixup" and switched a couple of plugs around. My idling is pretty good so I never thought there was an issue after that.

 

[Steven]

So, Chriso, what is your setup now? Which TSRM diagram did you use?

BTW, I note that the link 3p141592654 gave to the TEWD On-Line shows the same injector pairing and wire color coding as the Appendix in the TSRM.

I'm headed out now to check those series resistors 3p141592654 pointed out, now that the plugs are disconnected from BOTH injectors in the pair that has failed. That should simplify things.

It's about 35 degrees F here in Toronto near mid-day, so I figure my fingers should work for about 15 minutes. Snap-fit connectors get to be a real problem in this weather.

 

[Steven]

To wrap this up...

Once the wiring made sense (no thanks to the TSRM) tracing the problem was straightforward, and it turned out to be the solenoid resistor, as 3p suggested. With a little help from Adrenaline Phil and his parts bins, I was back running all six cylinders a couple of days before Christmas.

The correct injector pairing for my 1990T is that given by Shaeff, above. Changing from it does NOT work well.

I remain puzzled by the two other injector pairings in my TSRM. It is the first time I've found an error in the TSRM. My faith is shaken.

 

[Nick M]

The TSRM is traslated from Japanese, and not everything is correct. There are typos. 4Runners show 1.8 quarts on a drain and fill for the transmission for example, or something like that. And it actually takes 3.

You need the factory EWD to go with the repair manual. The fold out wiring diaram at the back is incorrect. It shows 87 models through 91, even though they changed.

The injectors are grounded in pairs. We are not blessed with sequential injection. If the US government did not require it, Toyota would not do it.

 

[Steven]

Nick, I have the electrical wiring hardcopy. It is the same as the foldouts in the TSRM and the same as the online wiring manual. It is wrong.

Are you saying the TSRM got printed with 1987 model info through all following years? OK, but how could the engine be changed?

Yes, the injectors are grounded in pairs. But what would be the point of that if they are all opened and closed at the same time?

Please expand on your comments a bit, for the thick-skulled this time of night.

 

[Nick M]

My 91 EWD does not match the fold out in the back of the 91 repair manual. It isn't way wrong either, but there are chasis differences. Since the car rarely needs repair, I don't have them out often to compare what all is different.

The injectors do not all open and close at the same time. They go in pairs, just like they are wired. The ECU does not drive the injectors, it provides the ground path.

 

[shaeff]

for what it's worth, i have my injectors wired as i listed, and my car runs great.

-shaeff