# How to test injector driver?



## cheapbird (Jul 18, 2004)

Hi all...

I've got a '92 that apparently has one injector not firing. Injectors have been replaced, valvetrain's mechanical has been ruled out.

So next to test is the wiring harness or the computer's #2 injector driver. The engine has a constant miss or stumble, and only one injector, when disconnected, does not impact engine performance at all. Any other injector causes the motor to stumble worse. (Plugs have been changed with no difference in symptoms.) Compression test to come depending on the outcome of the injector signal. I should add this has come about rather suddenly, the car was running fine and this started upon start-up after being parked for three hours.

Any ideas on a procedure to test if the injectors' harness is getting a signal?

Thanks, Keith


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## blownb310 (Jun 10, 2002)

cheapbird said:


> Hi all...
> 
> I've got a '92 that apparently has one injector not firing. Injectors have been replaced, valvetrain's mechanical has been ruled out.
> 
> ...


I use a diagnostic tool called a "logic probe" to test the pulse from the ecu. If you don't have one, the poor mans way to check it out would be to simply get another injector and swap it in. You probably simply need a replacement injector. I have replaced an injector in my wife's '90 in about 5 minutes. Unlike other Nissan models, changing injectors in the KA24E's is very easy! First pull the fuel pump fuse while it's running and wait for it to stall from lack of fuel pressure. This releases the pressure in the fuel rail. Then just remove the two 12mm headed bolts that hold the fuel rail down and gently pry up on the rail. They lift right out. It's really that easy. I've raided a few KA24E's in the junkyard and if you need a good used injector to test/repair you car with, send me a pm and I can send one to you for $20 shipped.


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## cheapbird (Jul 18, 2004)

blownb310 said:


> I use a diagnostic tool called a "logic probe" to test the pulse from the ecu.


Yeah, I've already replaced the whole set with a brand JY set that I pirated from a 240. (Some of the Stanza's originals were leaking) 
The "miss" seems to be in the same cylinder, and While I don't doubt it could happen, I think it would be a bit of a long-shot to put another bad one in the same "slot". Unfortunately, I think now I may have a burnt valve. Gotta do a leak-down test next. 

Thanks for the offer and info, I mainly work with Fords, and it amazes me how similar the Nissans are regarding EEC.

What I am finding out is, that I need a small O-scope to check computer signals...


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