well a simpler way of checking the connections at the injector without removing anything is backprobe the injector wires at the ECU with the key on, they should all read near 12v, if one is low or reading no voltage then there is a faulty connection or dead injector.

applying a quick sharp intermittent ground should give an audible "tick" from the injector.

 

heh but I dont think you'd hear it without exposing the injectors? or are they loud enough to be audible even With the UIM installed?

hah I gotta remember which oneso f the wires on the ECU are the ones for the injectors

I know the 4 grey and red / diff colors are some of them. hah

 

i just run the test wire to the engine bay and ground it up there, you can hear the injectors click with everything totally assembled.

 

Nat,

No need to pull the engine. Even though you still have all the emission and sequential stuff you can still get to all 4 of the injectors with a little effort and patience. I would recommend pulling the UIM off and disconnecting the secondary rail from the LIM. This can be done in 10-15 mins even with all the sequential stuff. Once you have the rail lifted a couple inches up away from the LIM, jumper the FP termninal and one of the GND terminals in the diagnostics box above the positive battery terminal(Black 1"x1" box). Turn the key to on position but dont try to start the car, this will keep the fuel pump running and pressurize the fuel system. The reason to do all of this is to see if one of the secondary injectors are leaking externally all the time. I have had several leaks from cleaned injectors. Start with this before digging in deaper and tackling the primary rail.

 

As a side note, has anyone found stock sized fuel injectors somewhere that work as good as the Mazda OEM`s do?

 

side feed injectors are quite uncommon, even stock injectors for these cars are quite large. denso is the manufacturer and i doubt you will find anything as adequate without changing the rails/injectors to top feed.

 

If you want to hear the injectors with the car on, a mechanic's stethoscope works very well. You can clearly hear the injectors while the car is running, and hear when the secondarys turn on as well. It takes a little working to get the probe on the injector body, but it isn't too hard.

I'd advise any serious mechanic to have a stethoscope. I've diagnosed many squeaks, ticks, and other things using it.

 

There is no possible way this is correct .. .if it is i'm getting one asoon as I get out of work .
Northern Industrial Mechanics Stethoscope | Automotive Diagnostics| Northern Tool + Equipment

are those mechanical stethoscopes THIS CHEAP ? 3.99 ?? somethings gotta be wrong here .

 

yes, it is just a tube to amplify noise to go to your ears.