I know... another thread.

I’m looking to see if anyone may know where I should start looking for problems in my harness.. I recently reinstalled my motor with a single and removal of nearly everything.. I had some trouble with my primary injectors not firing, and got lucky and made them work. I’m NOT satisfied that they are safe like this, or that they are even working right… so if you have any time, or experience with the wiring harness and primary injectors (Thanks already to clayne and those that helped me before) let me know if you have any ideas… I’ve dug through all the manuals and just can’t seem to find a relation between the wires, harness and function of the injectors..

Ok: Procedures went like this:

Tried to start car. Nothing.
Checked Spark = Good
Checked Fuel = Bad
Tested voltage to injector via testlight grounded to chassis = good
Tested injector function via 9V battery = good
Tried to start again = Nothing. No fuel still.

Went back to injector plugs after realizing that grounding injector to chassis didn’t tell me **** about the harness. Used test light on injector plug with neg side of plug as ground. With key on = nothing.
Decided to ground both injectors to chassis to determine if car will start aside from the f’d up harness = FLOODED.

With both injectors grounded to the same post, the car violently flooded. Removed ground..Decided to crank car with ground off (But both injector grounds still together) to try to unflood car = car fired RIGHT UP.

I’m lost now. To my understanding, what I have now going on is: 2 injectors using 1 driver to function.. Sound right? Why would tying the injector grounds together (while still connected to the harness) fire the car up? (I haven’t removed the t to see if it still fires though) If one injector ground was bad, I would still have initially been getting fuel from one injector, but I had NOTHING. If both were bad, then tying them together would have done nothing..

Sorry, no picture, but this should describe it. Both injectors (Primary) are still hooked to the harness. Both power and ground wires on both plugs on the harness remain INTACT. 1 wire is tied between the grounds (colored wires) on the harness. Kind of like a ‘H’ pipe on a Mustang..

If someone can help me determine where to look, and WHAT to look for it would be great! I redid the harness before installation, removing ONLY the sequential solenoids. Each individual wire is wrapped at the end and taped to the bulk of the harness. I triple checked it. Only one wire is broken… It’s a black wire with a red stripe and it goes on the back of the waterpump housing.. It’s the lower plug (There are 2) Other than that the harness is good aside from the wires I cut for the PFC which, by color, don’t match the injector wires in question.Sorry to confuse you if I did!

 

If clayne tried to help to no avail, then I doubt others would supercede him.

His knowledge base is well up there.

 

Agreed. No question about that!

Just trying to see if anyone has any other input... maybe even the man himself missed something

Doubt it, but it's worth a shot!

 

Justin....i just had an epiphany, lol. We found out that the FRONT rotor had no ground to the injector....we also tested the FRONT rotor for spark and looked for fuel comin out of the hole....but remember when i said it looked like you had a small amount of fuel mist coming from the v-band when u turned it over? we never checked the rear rotor for **** when it came to fuel. Its possible that you were trying to start it off of one injector, and it just didnt want to....or i could be runnin on 3 hours of sleep and not know wtf im talkin about, lol

-Zach

 

Zach,

Honestly? I'm positive there wasn't fuel in the rear either. I checked the DP several times and there was never anything.. Even one injector would have at least put gas in there.. I'm sure there's something wrong. Just not sure what, or how. We could always pull the patch and see it it's all just a fluke... but I doubt it. Can't hurt to try though.

 

so only one ground is working correctly?

You have a break in one of the grounds?

Did I read that correctly?

 

Well, it would *seem* that there is a break.. I used a test light in the harness and got nothing with the key in the on position. When I used the chassis as ground, instead of the harness, the light lit up. That's where I decided that the injector wasn't getting power, due to a broken ground.

I think my theory is flawed though... not sure where..

With the key in the ON position, and a test light in the injector plug (Positive pin for light and neg for ground) will I see a signal? Or is it only when there should be pulse? Or am I right in thinking that if I ground the plug to the chassis, and the light works there is a break in the ground wire for the injector somewhere in the harness? Jeeze this sucks.

 

have you check for continuity of the wires?

check at the injector harness and at the ecu plugs (prolly need to use wires to extend probe ends). The correct pin on the ecu and the harness should be zero.

If they are infact a closed circuit make sure it's not closed with anyother wires. just quickly check all the other pins to make sure the resistance isn't zero.

They should have a common ground to the ecu if i remember correctly. I don't have my fsm up here so i can't look at the diagram.

should be 4 signals for all of the injectors and one ground.

One of the solenoids terminals have ground hooked through it. I noticed that while i was cutting them off. Make sure u have the ground wired back up and is a close circuit to the ecu.

sound like your ecu ground is messed

 

you should only see a light when the injectors are firing. They do not fire when the key is on the on position. That would cause them to be open and just allow the presurized fuel to dump in your engine.

Duty cycle is just how much of the time they are open. You could say when the car is off it should be zero.

they are just solenoids

 

Yeah... Just reallized that was kind of a pointless test.. But oh well.


Thanks for the help.. I'm currently in the FSM amd looking for ideas.. I checked the connection at the ECU and all *looked* good...

Would the voltage check in the PFC tell me anything? I'm pretty new to the ECU..

Thanks!

 

When I get back from lunch Ill look through the Electrical Manual, but, for right now, why dont you take the harness out of the car and test it for shorts, and continuity on the injector wires...

I guess you could do that while its in the car, but with our cars its just as easy to pull the harness, or the engine for that matter hahahahahah

 

Yeah... I guess so. I'm going to re-test all the connections... I guess I might just yank it.. AGAIN.. goddamn car..

 

make sure you check to see that the fuel pump is grounded and that your feed line is on the feed line and same with the return. also check the feed and return on the FPR. when i did my motor swap those lines were crossed.
good luck

 

Thanks. Got that all under control.

 

make sure the ground is to the correct spot

 

here is the other end

If you make sure your wires do that u should be ok

 

i currently have similar problems it seems when i tried to start the car nothing happened it just cranked im guessing that one of the primary injectors got stuck open and flooded my engine with fuel. it sucks then after try to start it i leave it key (ON) position and i could hear a slight buzzing noise from under the uim i hope its just a stuck and cloked injector ?????????

good luck on yours mate .

 

Water thermo-SWITCH (not sensor). Pretty typical for this to break off. In some cases your fans will run 100% of the time without this connected so I would just resplice and solder it.

Now as far as:



I cleared this up with an electrical engineer friend.

Mazda has 12-14V on the B/Y side. The ECU provides access to ground through LG/B, LG/R for the primaries.

The hot side is present in B/Y, which receives battery voltage from the EGI relay.

That's why grounding them to the chassis resulted in 100% open.

http://www.rx7city.com/Manuals/93%20..._EMISSIONS.pdf

F-238, F-239

So technically you just provided another source of Bv to the other injector, not ground.

 

This could be an ecu problem, not switching the injectors.
You could do with an oscilloscope or take it to a shop where they could check it using a scope may be the best option.

 

dammit... Doublepost..

 

Ok, so does it look potentially harmful? Not that I won't fix it, but will it be ok to run like this while I do another harness?

 

From what it looks like you are fine there, Im wondering if B/Y was severed from your secondaries though, seeing that one of your primaries isn't working.....

 

God I hope not.

 

Not that I can see..

It's the same source of voltage anyways.

Now if your lg/r or lg/b were to be tied together, that would be bad, as one of the injectors would be actuated at completely wrong times.

 

jd, b/y is hot, use a multi-meter on the harnesses out of all injectors.

You will be able to tell if your secondaries will have any issues.