Injector not firing, Any test help

[StuartW]

Hi All i have lost combustion on no.5 cyl.

(See drag car link in sig)

 

I have a good spark, Have swapped coil packs etc etc. It has to be a "No fuel fault" I have just wired in a resistor pack and am running New 1200cc Prescision injectors.

 

I have succesfully continuity checked my wiring from injector + to each plug on resistor pack.

 

From ian C

 

"One wire is a 12v feed that has already run through the resistor pack, the other wire is switched to ground by the ECU to open the injector. The +12v wires will all be the same colour but the switched grounds will be different.

 

-Ian

 

Upon running and holding a DVM (Digital volt meter) on each injector i get a erratic 0.4 to 0.6V pulse (As expected) BUT nothing on my problem cylinder!

 

Is ther any more wiring or continuity tests i can perform?

 

I have done a continuity check on each injector whilst unplugged and they all read around 0.5-0.6 Ohms, As they should.

 

Regards

Stu

[Ian C]

Well either that injector isn't getting a voltage or it isn't getting switched to ground.

 

Voltage check:

Ignition on, position 2, car mobilised

Probe the +12v feed to the injector and battery negative for voltage. That should be a steady +12v on all 6 injectors.

 

If you don't see a voltage at #5 then your resistor pack may not be working on the output to that injector.

 

Ground check:

Engine running

Perform a continuity check between the ground wire coming off the injector connector and the battery negative. It should flicker. Digital multimeters don't respond fast enough for an actual reading but it'll either jump around the values or it'll stay rock solid on 'infinity' resistance. Check all six injectors this way, so you know what working ones should look like as well.

 

If you see infinity resistance then the wiring is interrupted between the injector plug and the ECU.

 

(you can disconnect the plug from the injector to perform these tests, easy then to just stick the probe up the plug, as it were)

[Lude]

had a problem on my 300zx with the injectors,

 

have you got a Noid light to test the injector?

 

 

for testing the injector, one of the prongs needs a power (not sure if its constant on the supra)

 

then the negative is from the ECU as youv mentioned.

 

 

just need to check its coming from the ECU, and not getting lost somewhere (split in the wire for example)

 

 

test with a noid light, their only a fiver

[MartinBattye]

backprobe the inj pin at the ecu.. if the ballast pack is ok and the injector is working then you will see 12v at the ecu pin.

[StuartW]

Thanks for replys.

 

I have done all of Ian c's tests and they come back good!

 

Going to google "Noid" light now.....

[Lude]

http://cgi.ebay.co.uk/Noid-light-Bosch-EFI_W0QQitemZ230446703937QQcmdZViewItemQQptZUK_Hand_Tools_Equipment?hash=item35a7b1a541

 

 

you just disconect the wire from the injector,

 

put the night light in the wire terminals,

 

 

it should flash rapidly when you turn the engine over.

 

if it does this, you know that there is negative from the ECU and also a posotive.

[StuartW]

OK, Made a noid light out of a test probe, Could not get it to flash on cranking, With all injector piggy tails removed.

Only constant illumination when connected to injector + and battery earth. Proves all resistor wiring ok?

 

At a loss with this test (Possibly wrong wattage bulb in test probe) Swapped the actual injectors around with a good one and still no good on original suspect cyl, BUT now with new plugs in the cyl that now relates to the original suspect injector still the plug is absolutely like new after a 30 second run.

 

Basically now Plugs 1,2 and 5 are clean and plugs 3,4 and 6 are black and sooted to shit. (As expected on base map)

 

Took inlet manifold off and spaced 1/2" away from cyl head, I can see ALL injectors venom squirting into inlet tract!

 

I have the Solaris ECU which i am sure Ryan mentioned changes the sparking system to wasted spark? and changed the way the Injectors work, Think he mentioned closed loop? Will do some reading up on solaris Tech.

 

Maybe that is why the Light test came up wrong. It cannot be wrong and that no injectors are getting any pulses as the engine fires up.

 

Gonna try now all new plugs and failing that wait for Ryans Input ...and double check injector wiring diagrams!

Edited April 1, 2010 by StuartW (see edit history)

[Ryan.G]

OK, Made a noid light out of a test probe, Could not get it to flash on cranking, With all injector piggy tails removed.

Only constant illumination when connected to injector + and battery earth. Proves all resistor wiring ok?

 

At a loss with this test (Possibly wrong wattage bulb in test probe) Swapped the actual injectors around with a good one and still no good on original suspect cyl, BUT now with new plugs in the cyl that now relates to the original suspect injector still the plug is absolutely like new after a 30 second run.

 

Basically now Plugs 1,2 and 5 are clean and plugs 3,4 and 6 are black and sooted to $#@!. (As expected on base map)

 

Took inlet manifold off and spaced 1/2" away from cyl head, I can see ALL injectors venom squirting into inlet tract!

 

I have the Solaris ECU which i am sure Ryan mentioned changes the sparking system to wasted spark? and changed the way the Injectors work, Think he mentioned closed loop? Will do some reading up on solaris Tech.

 

Maybe that is why the Light test came up wrong. It cannot be wrong and that no injectors are getting any pulses as the engine fires up.

 

Gonna try now all new plugs and failing that wait for Ryans Input ...and double check injector wiring diagrams!

 

Solaris/syvecs runs Seq ignition and seq injection chap. None of that crap wasted spark here

 

If they are new injectors then i would suggest getting a battery and hook the injector straight up to that and see if it clicks as they have a habit of sticking if not used for ages. If it doesn't click using a battery then give it a tap on the bench. Usually does the trick.

 

If it works on the battery then try again and if it still doesn't work then i will talk you through how to use the output testing on the S6 which will come in handy for testing each injector with the engine not running.

 

Ryan