Question Regarding Fuel Injectors

[Papasmithnc]

Looking at the difficulty of replacing an injector even without removing the plenum and such, I want to make sure that I have accurately identified the right injector that has failed.

In pursuit of that and as suggested I bought a mechanic's stethoscope. I tried using this diagnostic method but, with all the ambient noises of the engine, I could not hear clearly the clicking of the injector firing. Maybe I am not putting it in the right place but, I think I am.

Looking for another solution, I was at Advance Auto and they have this 20 some dollar kit that will let you know if the injector is firing. My understanding is, this will tell you if there is an electrical problem, for example bad coil, that will prevent the injector from firing. My concern is, will this tell you if the injector is just plugged up?

Basically I need some direction as to how to make sure I have identified which injector(s) need replacing.

Thanks,Dave in NC

[SteveTheTech]

Hey there I am on the way out the door, I will elaborate in a little while, unless someone beats me to it

You need to do a resistance check on all the injectors.





http://www.nicoclub.com/FSM/J30/1994_J30/ec.pdf

page 121

Good luck

[gr8scott72]

Hey there I am on the way out the door, I will elaborate in a little while, unless someone beats me to it

You need to do a resistance check on all the injectors.





page 121

Good luck

Seems easier to check the resistance right at the injector.

Even before you ohm the injectors out, just start unpluging them one at a time with the engine running. When the idle does NOT change as you unplug one, that is probably the bad one.

You can also check with this method by just unplugging the coil pack harness one at a time. It will do the same thing and they are easier to get to.

[SteveTheTech]

That would work it's some of them are a pain to get to and this will check the integrity of the sub harness as well, and make sure the connectors are not damaged.

Either way works just fine.

[driverdriver]

remove the engine cover and do an ohm test on each injector. If the injectors are in the 10-14 ohm range they're good. If they are above or below, they're bad.

[coolyun_98]

There are some rare cases that the lower injector o-ring might be leaking gasoline to the cylinder. If so, even if the injectors themselves are in working condition, you will get lower fuel pressure and a rough running engine.

[GerryO]

An injector or harness connection that has failed totally electrically (infinite resistance reading) should cause the CEL to turn ON. A bad/open injector coil will probably work intermittently for a while, before it fails completely.

Removing the connectors and using a mulimeter to check the resistance of each injector is pretty easy and disconnecting and reconnecting the coil packs one at a time with the engine running will indicate which cylinder is the problem.

Whatever has gotten past the fuel filter without clogging it, would probably clog more than one injector.

Is your CEL ON and have your pulled any codes (which is more difficult than checking the resistance of all six injectors)?