We just installed my new engine, along with a new replacement harness, the engine will crank but will not start, its getting spark, the ecu is initiated, but does not seem to be getting fuel. This plug does not seem to go to anything and was not on the old harness. It is on the right side in front of the shock tower and near the air flow meter.

I took a picture of it to show you all. It was covered in blue tape when we unpackaged it.

We haven't had time to trace the circuits yet, we just wanted to know what this plugs to.

 

it plugs into the resistor pack for the fuel injectors.
If the car has LO impedance injectors then they use that resistor pack and add the resistance so that the ECU sees HI impedance.
You can't just have that disconnected.Th injectors will not see power.
(UNLESS someone bypassed it Before that connector and wired it to HI impedance injectors).
Is there any other Modifications done around that area?..and do you know what the injector impedance is?

 

That is kinda what we thought.

The car came with, and still has high impedance injectors. I bought the harness from Mazdatrix and told them it was for an '88 turbo.

Thanks!

Now, how do I get around it or do I have to find the right harness?

 

Only one harness is listed for '86-'88 turbos.

There must be something that is suppose to plug in that connector. We will look it up in the FSM.

Thanks.

 

That connector plugs INTO the resistor pack.
86-88 ran LO impedance
they changed around 87.5 to HI impedance with NO resistor pack and the harness omitted that connector.
NOW if you Have HI impedance injectors(best to double check).then you can either cut and splice that area of wiring OR get a old resistor pack and use the connector off it.
what you do is Gang all the wires together and it creates continuity to the injectors.

 

Actually, my car came with high impedance injectors, my old ones were the pink ones and I bought new ID high impedance ones. My old harness did not have that connector, and I have no resistor pack on the car. There must be a jump connector that I should have gotten with this harness.

 

You woudn't get a jump connector with the harness. Just do like styx said, connect all the pins (I don't like cutting harnesses, so I'd just use wires and connectors).

On a car with fuel inj. resistor, one of those wires would send 12V to one side of a resistor, and four would come out on the other side of the resistor to the injectors. The ECU supplies the ground to turn the injectors on.

See post #2, pic. #5 here:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/pictures-various-sensors-na-reference-671004/

 

Mazda superseded the harness so instead of an 86-87.5 harness and an 87.5-88 harness, when you order a new one, you get the 86-87.5 harness.

so the harness is meant for low impedance injectors, if you have the high impedance injectors still, find a used resistor pack, and cut the resistor off, and solder/crimp the wires together. in the future if you go to low impedance injectors, the resistor pack will be plug and play.

 

odd that mazdatrix would sell you the wrong harness without asking, considering they should know better than the early harness would NOT work.

find an old resistor pack and cut the connector off, cut and bunch up the wires and solder them all together and wrap the bundle. problem solved.

edit: or what ^ said.

 

I got a resistor pack,but you would only be using it for the connector.
If you want it let me know.cover shipping.

 

lol i was gonna say, listen to the parts guy!

i bought a new harness for mine in like 1999, so i ran into this. BTW the new harness is a work of art, its beautiful.

 

We made a one wire to 4 wire jumper, so it starts now.

Now, we have 2 other problems, the alternator froze up(one of those super-duper ones) and its only running on 1 rotor. we have good compression and spark, so, he thinks one of the injector plugs is not secure. Anyway, he told me I should be able to pick it up on Friday.

Thanks for all your help, that's what got it running for us.

 

not all that uncommon, have him check for a pushed in pin on the connector while he has it apart and test the injectors themselves to make sure one or more isn't stuck shut.

 

Are you driving it now? How is it running?

 

Runs Great!!!!...as near as I can tell. I can't really jump on it...gotta do the break in thing.

Changing to S5 turbo rotors gave me the most immediate improvement of not being so dead off boost. Other than that, it runs smooth and starts easy.

So, now I get to drive like other people my age drive for a couple thousand miles.