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Troubleshooting MPFI injectors-83/84 turbo


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My 83 Turbowagon is nearing completion and I have this nagging problem that I cant figure out.

 

The car will crank over but will not start without flooding it out on fuel injector/carb cleaner.

 

I have tested the injectors themselves and when I apply a small amt of voltage to them they will click but I am not getting the signal to them from the car. I have gone thru my 83 factory service manual supplement (turbo specific book)'s flowcharts and am getting nowhere.

 

I am open to ANY suggestion. This car is kindof a basketcase that has taken me years to get to where I am now with interesting hurdles to cross such as:

 

No Fuel pump relay installed in car.

Wires to fuel pump itself cut.

 

If I connect the green connectors the fuel pump cycles on/off.

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Shawn,

 

Usually the injectors have voltage applied to them on one side of the coil. When it is the proper time to open, a ground connection is applied to the other side of the coil through the ECM. There may be some terminating resistors going to ground also that the current passes through.

 

Check to see if you have voltage at least getting to the injectors. If you do, then the problem may be due to the ECM. It is critical that the ECM sees the ignition is firing in order to open the injectors.

 

I will do some more research for you later when I get time.

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I not sure for subaru but most efi systems have a start plan, batch fire, release... You are saying your getting no signal at all from the pcm when cranking? I'll do some digging around for inputs for the fuel system but just to let you know your subaru most likely has a clear flood mode when starting at wot, the injectors won't open if the throdle is wide open test in cfm is worthless.

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I would say then that that means power is getting to the ECM but it would be good to check it out. Before you do, check for voltage getting to the injectors because that is what we really need to know. If you have 12 volts on both sides of the injector coils then that would mean that the grounding is getting to them from the ECM and it may need to be replaced.

 

The injector return leads appear to be going to pins 21, 22, 25, &30. The respective colors are wht, wht/blk, wht/red, wht/blu. Check to make sure pin 26 (fuel injection control) has voltage on it also. The green fusible link supplies power to these points.

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I would say then that that means power is getting to the ECM but it would be good to check it out. Before you do, check for voltage getting to the injectors because that is what we really need to know. If you have 12 volts on both sides of the injector coils then that would mean that the grounding is getting to them from the ECM and it may need to be replaced.

 

The injector return leads appear to be going to pins 21, 22, 25, &30. The respective colors are wht, wht/blk, wht/red, wht/blu. Check to make sure pin 26 (fuel injection control) has voltage on it also. The green fusible link supplies power to these points.

 

Cougar:

 

Im not understanding too well but its not your fault. Im a little wiring challenged sometimes and yet I can do the ej22 wiring harness conversion in a couple hours (most ppl take a full weekend to do it). Yes, thoughts of putting the 2.2 in here instead of figuring this out are VERY tempting.

 

I have 12 volts to the pin 26 one you referenced.

 

I have continuity between these pins and their respective injectors.

pins 21, 22, 25, &30.

 

Can you spell this out for me a little:

If you have 12 volts on both sides of the injector coils then that would mean that the grounding is getting to them from the ECM and it may need to be replaced.

 

Whats "both sides" mean?

 

I tried another ECU, in fact 2 others without success but I dont know them to be good. Im hoping a friend of mine will let me borrow her 84 Turbo coupe so I can do some comparison to a running one.

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Can you spell this out for me a little:

If you have 12 volts on both sides of the injector coils then that would mean that the grounding is getting to them from the ECM and it may need to be replaced.

 

Whats "both sides" mean?

 

During 'normal' operation, if you placed the ground lead to a DMM at a ground point on the body, and placed the other DMM lead at the injector, one side of the injector should read 12v, and the other side should read 0v (or very close to 0v). In this case, since cougar thinks the ECU isn't grounding the injectors, you would most likely read 12v on both sides of the injector.

 

This basically means that there is either a break in the wires going to the ECU, or there is a break in the traces/transistors inside the ECU. Since you said you checked continuity in the wires, and tried different ECUs... I'm not sure what else that leaves :confused:

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I am doing some troubleshooting of my own on an 88 ea82t. Can someone tell me if this is okay?

Key off, 12V on both wires to injector.

Key on, 12V on +red and 0V on -white.

Engine running, 12V (rapidly fluctauating) on both wires. (crap! I'm not sure if that's correct)

Injector resistance and resistor pack values are good.

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Shawn,

 

The resistance of the injector coil is low (2 to 12 ohms) so when you check the voltage on either side of the coil, with the meter reference lead to ground, you will see the same voltage, if no current is flowing through the injector coil. Voltage is tied to the coil at all times when the ignition is ON but current only flows through the circuit when the return side is grounded (through the ECM) and the injector then opens. The ECM decides when to make the ground connection and open the injector.

 

Looking at my info again it shows the the injector grounds are tied to pins 27, 31, 32.& 33 of the ECM connector. Check those points with a ohmmeter and with the ignition OFF to make sure they are grounded. Also check that pin 5 is grounded.

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Ive got 0 volts on both sides. :(

 

Assuming thats 0V W.R.T an actual ground, then there is a prob with the +side supply of the injectors - should be 12v "hot at all times". That taps straight off the line that supplies power to the ecs (ie its got nothing to do with the ecs at all).

Check that your ecs is getting +12V with the ignition switch off, should be a red wire. There should be a connection to that that goes to the + side of the injectors.

 

Sorry, no idea of pin #s, i'm looking at a crappy haynes manual. Have you got a wiring diagram? I can post a copy of this one if you'd like..

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The flucuating voltage is a good sign that the injectors are working. The return line is plused on and off to ground by the ECM to open the injectors.

 

 

 

I am doing some troubleshooting of my own on an 88 ea82t. Can someone tell me if this is okay?

Key off, 12V on both wires to injector.

Key on, 12V on +red and 0V on -white.

Engine running, 12V (rapidly fluctauating) on both wires. (crap! I'm not sure if that's correct)

Injector resistance and resistor pack values are good.

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As was stated by Naru the problem is most likely due to the fusible link. Provided the links are in the proper positions you need to check the green link. It ties to a wht/blk wire that supplies power to the injectors along with other things. The problem may just be a bad connection so check that.

Ive got 0 volts on both sides. :(
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