Fuel injector questions


Pix3L8

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Alright ladies and gentlemen, back again with another problem I could use your help with. I’m having difficulty finding the correct order to connect my fuel injector wiring harness to the injectors. “I HAVE seen the thread about it but I’m skeptical still”, last time I went messing around with my injector wiring I backfired the engine and caused a fire. Adding to everyone’s opinion that I should just dispose of the truck before it makes me go bankrupt at the ripe age of 22...sooo I want to make sure I get this perfect the first time. I know the 2.9 is a bank fire system and from my understanding the green and white wires go to one bank and the red and tan to the other? Correct? That being said what are the banks cylinders 1,2,3 and 4,5,6? I’ve found a few sources in the ford truck forums saying as much and on here I saw cylinder 2,4,1 and 6,5,3. What would be really helpful is a picture of someone’s harness on the truck so I could see which wire is going to which injector. Side note the truck body is an 89 the engine is an 87(if that matters at all) also from my understanding the wires going to each bank don’t matter particularly which injector they go to as long as it is in the correct bank right? I just went through and rebuilt the engine, ran it, caught it on fire, and then replaced the whole electrical and ignition system AGAIN, all of this was my own fault but before I turn that darn key again I want to be sure I have my fuel system wiring 100% correct
-Jon
 


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RonD

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Passenger side is Bank 1, drivers side Bank 2, of any "V" engine FYI
Ford numbers V6 cylinders like this:

3 6
2 5
1 4
Front

2.9l Batch Fire has:
1 2 4 injectors sharing one ground wire, Pin 58 on computer
3 5 6 injectors sharing the other ground wire, Pin 59 on computer

If you look here: https://www.justanswer.com/uploads/molurch/2006-12-01_235512_2.9Bronco2.jpg
You will see firing order for 2.9l, 1 4 2 5 3 6

1 4 2 then 5 3 6.........................so a madness to their method, lol, it may not matter much but I would stick with the pin 58(1 2 4) and 59(3 5 6) assignments


4.0l is different, it did do 1 2 3 on one wire and 4 5 6 on the other, so Bank Batch fire
 
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Pix3L8

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That just seems so odd to have 2 injectors on one side and a single injector on the other fire at the same time..although that’s the general consensus I got from my research it just seemed weird that’s why I posted.
 

RonD

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Batch fire is one step up from a carb setup

A carb used airflow passed the Jets to keep the intake full of air/fuel mix so an opening intake valve would suck in what it needed
There is a bit of waste as the fuel will coat the intake's internal passages, so it must add more fuel than needed to compensate for this, ain't much but ain't 0 either :)

Batch fire does the same thing, but a little less waste in coating passages, lower intake has the air/fuel mix and an opening intake valve sucks in what it needs
Fuel injection also has the advantage of better "on the fly" air/fuel adjustments, which even "feedback" carbs didn't have

Sequential injection is more efficient because there is less waste, you still get a coating on the head ports and back of intake valve, but less on the internal intake passages

Direct injection has the least waste, so much more efficient

I guess with newer computer software using Bank Batch fire would be better for Lean/Rich diagnoses on one Bank
But your computer will be using older software so I would stick with the designed injector wiring
 
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adsm08

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4.0l is different, it did do 1 2 3 on one wire and 4 5 6 on the other, so Bank Batch fire
At least some years split the batch the same way the 2.9 did.

I ran into that when I built the injector harness for my attempt at a SOHC swap.

I think I modeled my attempt off a non-California 94.
 

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Sequential injection is more efficient because there is less waste, you still get a coating on the head ports and back of intake valve, but less on the internal intake passages
On paper.

Batch fire systems generally get better MPG, which makes no sense at all, but has been reported as a real world observation by a few people here.

I am running one of each and don't really notice any differences. Over the summer my B2 (batch fire) was getting almost 19 MPG, while my Ranger was getting used as a lawn ornament.
 

RonD

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Yes, it would make sense to use Bank Batch fire(123/456) when they switched to 2 upstream O2 sensors, so had Lean/Rich Bank diagnostics, which probably wouldn't work as well with the 124/356 wiring
 

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I always thought that multi port fuel injection was the best thing since sliced bread. I had an old carbureted 2.8l and that thing was a pig, the 2.9 was night and day difference in power. I didn’t realize how basic batch injection actually was . The fuel injection makes a big difference especially in the winter below freezing when I have to cold start the truck.
 

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ok guys update time. I got new injectors, dizzy and sensors installed, everything seems to be working great except I have no injector pulse. my harness was damaged In the fire so I picked up another harness from a pick and pull yard. I have perfect continuity throughout the harness so it should work, it also has the injector plugs labeled which is a huge help. RonD mentioned pin 58 and 59 on the ECM should ground out the injectors. If I want to test the wiring from the emc to the new harness that I just got (ignition off) will I have 0 ohms at the ECM pins? im trying to figure out if the default state of this system is to keep the injectors grounded until they fire or if they ground out to fire. im figuring if the new harness is good and the injectors are brand new (and yes I have fuel pressure at the rail) it must be a wiring issue somewhere between the injector harness and the ECM. My only other idea is it may be the harness going to the ICM on the back of the distributer, that was badly damaged and I bought new pigtails and had to DIY one together.
 

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IIRC it grounds out to fire.
 

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The computer will have NO ground on pins 58 and 59, if they were grounded all 6 injectors would open up as soon as you turned on the key, major flooding and hydro-lock

The computer grounds 58 and 59 based on the PIP signal from the TFI module, essentially the spark pulse
When you crank the engine over the sensor in the distributor sends out the timing pulse(PIP) to the TFI module so it can start/time Spark
TFI module passes on that PIP signal to the computer so it can time the injectors
Without the PIP signal neither the TFI module or computer would even know you wanted to start the engine, i.e. there is no connection between engine control systems and starter motor circuit

Spray fuel into the intake and try to start the engine, 50/50 test
If it starts and dies then yes your fuel delivery is not working
If it doesn't start then No Spark, so check TFI system first

The ground for the injectors is milliseconds long so can't be seen on a Volt Meter, or test light, you can get a NOID light, it plugs into the injector harness and will flash if the ground is pulsing while cranking the engine
 

Pix3L8

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The computer will have NO ground on pins 58 and 59, if they were grounded all 6 injectors would open up as soon as you turned on the key, major flooding and hydro-lock

The computer grounds 58 and 59 based on the PIP signal from the TFI module, essentially the spark pulse
When you crank the engine over the sensor in the distributor sends out the timing pulse(PIP) to the TFI module so it can start/time Spark
TFI module passes on that PIP signal to the computer so it can time the injectors
Without the PIP signal neither the TFI module or computer would even know you wanted to start the engine, i.e. there is no connection between engine control systems and starter motor circuit

Spray fuel into the intake and try to start the engine, 50/50 test
If it starts and dies then yes your fuel delivery is not working
If it doesn't start then No Spark, so check TFI system first

The ground for the injectors is milliseconds long so can't be seen on a Volt Meter, or test light, you can get a NOID light, it plugs into the injector harness and will flash if the ground is pulsing while cranking the engine
Awesome, I’ll do more investigating this weekend and report back
 

Pix3L8

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Ok report time, I got home and hooked up the new harnesses to the fuel injectors, and nothing. I have 12.10 volts at both wires going to each injector key on, fuel pressure at the rail and I’m still stumped. I’m going to go through my timing again and make sure I’m not 180 off because that’s the only thing I can think of. I have spark but it just kinda puffs and backfires through the intake when I add starting fluid but won’t start
 

Pix3L8

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Ok report time, I got home and hooked up the new harnesses to the fuel injectors, and nothing. I have 12.10 volts at both wires going to each injector key on, fuel pressure at the rail and I’m still stumped. I’m going to go through my timing again and make sure I’m not 180 off because that’s the only thing I can think of. I have spark but it just kinda puffs and backfires through the intake when I add starting fluid but won’t start
Update on my update, timing was 180 off and there was air in the fuel line. Got it “running” for now just going to figure out getting the timing all set to spec and go from there
 


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