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Injectors not active

9K views 31 replies 10 participants last post by  walleraubree4 
#1 ·
hello mx6 people!

ive been peeking around this site for years, been avoiding it up until now.

figured if i have problems and serious questions, i should go to a mx6 specific site...

heres whats up, this is a copypasta from my original thread:

-------(first post)

After playing musical chairs with alternators, I finaly went back to the original with a bad volt reg...


Started, idled, died.


Found a blown main fuse (80), replaced, now fire.

Fuses under dash, all good

Main block fuses, fine

Spark, check

Fuel pump, check

Injectors, ?

Tried push start with a friend towing me, nope.

Could be a relay or a circut thingie somewhere somehow....


--------(second post)

took line off fuel filter and cranked, nice even flow of fuel came out...

so the pumps fine. but i already figured that.

took plugs out and cranked, all spark.

so its injectors, has to be.

both grounds on the injector harness, (egr side, and tb side,) are tight and clean.

--------(third post)

did some searching using the pmx626 thing (thanks ndm!)

so the EGI fuse on the under hood box is for the injector and fuel stuff huh?

hmm. mine isnt blown, but it isn't clean..

i swapped the EGI with the heater fuse since i don't even have a heater anymore.

different amp rating but whatever, still didn't start.

so i guess its not it? ill get a new one any way. shit ill get all new ones.

--------(fourth post)

replaced 30a EGI main block fuse.

replaced poor condition positive cable terminal.


--------(fifth post)


Replaced:

Alternator with good

Both yelow realys on the firewall

Black circuit thing with red dot

Still no start.


Injector plugs get 0.0 volts at crank.
 
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#2 ·
------(sixth post)

stopped by a really friendly mazda-nissan hole in the wall mechanic.

had a nice conversation, he actually CARES to solve this problem, just offering advice, no rushed "your not even paying just asking for help" type thing.


i got about 5-6 pages of wiring diagrams, showing relays and everything down to every detail.


when im back home i get to trace wires testing ohms and looking for crispy things..

there is a black relay, or at least a black cube with a green circuit board in side of it, sitting directly behind the ecu.


can anybody tell me what it is?


--------(seventh post)

$75 an hour if i took it in.

hmm no thanks.


1. why did the 80a fuse blow ( bad alternator maybe?) new alternator in now anyway

2. why are injectors not firing
a. main relay 1 replaced, relay 2 replaced, egi fuse replaced, main fuse replaced, fuel pump has power
b. black relay behind ecu still a mystery


relay # 1 and 2 both have current going to it, going out im not 100% certain yet.

if it wasn't going out it wouldn't make since, as i now have a total of 6 spares.

im beginning to think its the ecu, as thats where the injector drivers are im told.

------------

so there you are.

covered what happened, what ive replaced, and where i am now.

im well aware of the reputation this site gets, and i don't want to be chewed out my everyone and their brother.

if i worded, said, typed, or did anything wrong im sorry, and tell me how to fix it.

im looking forward to any help i can receive here, thanks so much in advance.
 
#3 ·
your injectors may have been over driven. Take off the clips and see if you get an ohm reading using a multimeter. If you do, should be between 11.5-13.*

When those check OK, take off the clips to your ECU and measure the injectors for resistance.
 
#4 ·
Will do zach, thanks


Also, I forgot to add that I've also swapped out all injectors with known good.
 
#5 ·
key in, cluster lights on



-----



----

(side note)

what is this?

 
#6 ·
i keep forgetting im not allowed to edit yet..

i should have joined 4 years ago....

that black relay is located behond the ecu fyi.


one of my diagrams i have says the injector wire out of the ecu is yellow, then yellow and black, is this correct?
 
#7 ·
#8 ·
2 weeks and counting. awesome...

getting power at both sides of plug when black probe is grounded...




should i be looking for anything here?




unplugged relays while on, both click when plugged back in, so they are good.

has to be ecu right?
 
#10 ·
ask and you shall receive



----


#1, 14 to 13.9

#2, 13.9

#3. 14 to 13.9

#4, 14 to 13.9
 
#11 ·
well they are good and they are getting power and injecting fuel. I wonder if your fuel pump is pumping too little fuel. Having fuel come out of your fuel line is one thing, having it come out at the correct flow is another.

did the fuel flow out of the hose or did it somewhat shoot out?
 
#12 ·
It was a calm torrent. A strong flow.

Def not a trickle.
 
#13 ·
I'm not confindent about the injecting fuel.

After multiple crankings and pulling plugs nothing smells like fuel.

Not even moist.


Ill tripple check that though. I even cranked with a plug out. No mist or anything fuel related.
 
#15 ·
Here's a simple, perhaps even dumb, question.

Is your timing belt good? Are the cams turning when you crank it?
 
#16 ·
Lol yea belt is fine.


Let's just assume the injectors arnt working.

I know for a fact.


Every relay is good. Maybe not EVERY but tbhats what I'm trying to narrow down.

Fuel pump is good, circute opening relay is good.


Both sides of injector harness plug get +12.


So what else controls the injector pulse, just the ecu right?
 
#18 ·
Goin to a yard in less then an hour.

Pickin up:

Ecu

Ignition control module


Let's wait and pray gentlemen
 
#19 · (Edited)
well after 154 views on this thread, and only one reply that actually helped....

i should have named the thread something different, i named crank but no start on the other place...

too many people fixated on the injectors, not what was CAUSING them to not fire.

picked up a 60$ ecu out of a 89 626 5speed.

whats missing in this picture?



THE CAR MAYBE?????

AHAHAHAHAHAHAHHAHAAHAHAHAHAHAHA

YESSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


bad alt < main fuse < relay #1 and #2 < ECU

what a chain of events
 
#21 ·
Indeed.

I'm just happy it moves
 
#23 · (Edited)
Lol

Yea I specifically haven't posted too many in depth pics of the car on this forum cause I know how people loooove to flame. I just don't wanna deal with it.

not in a "you guys are a-holes" way. i don't mean it to come off negative.

more of a,

i don't want to cause the situation to begin to happen. if that makes sense.
 
#25 ·
Oh of course.

: )
 
#27 ·
I don't know if the injectors power passes through the fuel pump relay.
But I would say no due to the fact that the factory workshop manual say to pull the fuel pump relay and turn the engine over to drain fuel pressure.

Are you sure the relay is bad?

There is a yellow two prong plug next to the drivers strut tower, it is beside a single prong green plug, if you jump the two sides of the yellow connector (connect one to the other) the fuel pump comes on without the engine running.
The green plug is the test connector, ground it to the frame and you can pull the engine codes with the check engine light in the cluster.

How many pins are on the relay?

Relays are actually quite simple.
-They use 12v positive and Ground signals to pass (Normally opened) or turn off (Normally closed) a current, it can be negative or positive.
IN current 12V+-> Relay ----->OUT current 12V+
Signal in 12+---->_____<----Signal in Ground

The above relay would be passing a 12V+ current (IN-OUT)
It would be normally opened (needs 12v+ and ground signal to pass current)
Only one signal needs to be switched, the other signal and supply (in) current would be constant.
So if the above N.O. relay was for the headlights, 12V+ leaves the battery, passes through a fuse and goes to the in 12v+ current side of the relay. The ground signal going to the relay is permanent on. The 12V+ signal to activate the relay comes from the headlight switch.


Check the female prongs the relay plugs into using a multimeter.
How many wires run to the fuel pump?
If it's one than + is switched by the relay.
Check the female prongs voltage with the key off for a 12V+ prong ----> current in
Check for a ground signal with the key off ----> ground signal in.
Check for a positive signal with the key on ----> 12+ signal in.
The remaining prong will go to the fuel pump ----> Current out

By a 4pin 40amp 12V Normally Opened universal relay, get some male and female spade connectors.
Take 4 pieces of 18" wire and crimp 1 male and 1 female spade connector one each wire.
Plug the male end into the factory relay socket the relay sat in and the female prong on the universal relay.
The pinout will be:
Relay 30 <----> Current in (Factory socket)
Relay 87 <----> Current out (Factory socket)
Relay 86 <----> 12V+ signal in (Factory socket)
Relay 85 <----> Ground signal in (Factory socket)

Tie wrap the wires so the spade connectors don't come loose and secure the universal relay somewhere out of the way.

To trouble shoot your issue you can jump factory socket current in and current out, bypass the fuel relay and see if the car runs properly.

To add to the info in the dead thread you posted in. The injectors are batch fired 1+3 and 2+4 the ecu activates them, RPM+TPS+VAF+02 signals to the ecu decide the amount they inject but the hall sensors in the distributor dictates when they fire, the other signals have default maps to compensate for failed or bad signals but without the hall sensor signals in the distributor the ecu wont inject fuel or run spark.
 
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