REAL TIME-Injector wiring help!!! (1 Viewer)

[yodafrick]

So last Sunday I dove into the wiring harness cause my 87 4runner was running on three cylinders. No. 3 was firing but no change of misfire when I pulled the plugwire from the cap. After some research, I dove into my wiring harness and low and behold, the negative wires fell apart when I untaped the 4 into 2 connection. Had bad luck soldering so I put it all back together with butt connectors (I know, I know). Ran good for two days and then started misfiring again in the foggy, rainy weather we've had.

Fast forward to today. Tore it all apart again, soldered all the connections, positive and negative, put it all back together, and now one and three aren't firing. These are both connected to each other back to the computer (yellow wires). Wires look good, join is decent. I'm stuck. Could it still be the negative wires? Is there any way to check continuity or something? I don't want to just resolder everything and put it back together again only to find its still misfiring. Is there a way to test the injectors before I tape up the harness and bolt up the plenum? Gotta get to work tomorrow, any help will be appreciated.

 

[yodafrick]

I see the positive (blue for 2 and 4, yellow for 1 and 3) go to a resistor. Could this be shot? Rejoining wires and checking for bad wires again now.

 

[Bogo]

The FSM has injector testing criteria. Basically it boils down to hooking up power to them and seeing how much flows through in X period of time. you do need to collect the gas up so you can measure it, and keep sparks away so you don't ignite the gas.

 

[Bogo]

Continuity can be check with a DVM on the ohm setting if it doesn't have a continuity check. 0 ohms is a dead short. You can also use a battery, light bulb, and some wire.

 

[pappy]

I see the positive (blue for 2 and 4, yellow for 1 and 3) go to a resistor. Could this be shot? Rejoining wires and checking for bad wires again now.

I would double check. I believe 1&2 fire together, and 3&4 fire together. Ground is ground and I don't know why Toyota runs 4-to-2. When I repaired my harness I took the grounds 2-to-1 matching the wire colors.

 

[yodafrick]

Thanks all. It has been very wet here in the Northeast and when it cleared on Tuesday, she decided to run beautifully. I am leaning towards a hairline crack in the Napa cap I purchased. May just go OEM. Or possible wiring issues/dampness in or near the ECU. We'll see what happens when it rains again.

I did check continuity to and from all injectors and the resistor and all was well. Didn't hook a light up to the injectors yet that and swapping 1 and 3 for 2 and 4 (injectors) was my next step to see if the problem followed the injectors or stayed with the wiring.

I'll keep ya updated.

And yes 1 and 3 are butted together (yellow wires) and 2 and 4 are butted together (blue wires). Thanks again!