Firing the Injector

[kena]

Simple question, what signal tells the computer to fire an injector ?

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[CheapThrillB2]

the distributor......well the pick-up in the distributor

 

[almostclueless]

The computer opens the injectors based on it's programming and sensor inputs.

 

[kena]

But which wire gives the command signal ?

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[CheapThrillB2]

white and tan are the signa; wires from the computer

 

[kena]

Great !

My wiring diagram shows a "coil resistor" on the Tan/White wire. Can you tell me where this resistor is located ?

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[CheapThrillB2]

my schematics show nothing between the injectors and the computer

white/tan straight to computer
Red wire goes two places
1. Idle Speed Control Solenoid
2. Runs to a conjuction off the ee/fuel pump relays and other 12 volt references for other sensors

My book is a 1989 Shop Manual.....I assume this is for the 90 ranger in your sig?

 

[kena]

I misunderstood. I thought you were talking about the Tan/White wire from the distributor module to the computer.

I understand that the computer fires a bank of 3 injectors with the Tan wire and a separate bank of 3 injectors with the White wire.

The original question still remains:
What signal tells the computer to fire an injector ?

Somehow, the computer must know when to fire one of the banks of injectors.


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[CheapThrillB2]

whats your problem......r the inj not firing?

 

[CheapThrillB2]

Distibutor/TFI-IV

"On the closed bowl distributor, the pip sensor sends 2 parallel output signals. One signal goes to the externally mounted TFI-IV ign module for "STAART" and "Limited Stragety" mode operation. The other PIP signal goes to the ECA to allow the computer to calculate crankshaft position and RPM in order to control Timing and Fuel Injection."

 

[kena]

Correct. My injectors have refused to fire.

 

[kena]

In fact, they scoff at my meager attempts to troubleshoot the reason.
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[CheapThrillB2]

Do you have spark?

I had a EEC relay go bad. But i started diag the no pulse at the injectors before i realized i had no spark and no pulse at the same time. Ended up a bad EEC relay. But i have replaced several TFI (Ignition/Control Module) modules as well creating the same condition.

 

[kena]

Sadly, I do have spark. I even switched out the computer with a known good one. Fuel pressure is good too. All to no avail.
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