I know one of my injectors is bad and I have everything I need to replace it. I have the instructions for replacing an injector, but I don't know how to figure out which one it is. It has not thrown a code and might still be slightly working. Please let me know how I can determine which injector to replace.

Thanks in advance

 

well i'm going to assume you've got 2 maximas b/c your username is 99 SE Limited but this part of the forum is for 89-94 maximas... so i'm guessing you have one of those too. but on any gasoline engine, you pull the spark plug wires one at a time until you find whichever spark plug wire does NOT cause the car to run any worse. If you pull 1, 2, 3, 4 ,and 6 and the engine stumbles worse, but you pull 5 and it runs the same... then injector 5 is your problematic injector. and just in case it wasn't clear, you put each wire back on before pulling another one off.

 

they have a thing that lights up when they are good and dont when they're bad.

 

Noid light.

 

An automotive stethoscope is what I use to diagnose faulty injectors. Then I pull the plug on the suspected one to confirm it.

 

The light on Mymaxs head must be out...

Like the first responder said, pull the spark plugs. Quick, easy, tells the story.

Just make sure you're not grounded so you don't get a good jolt if the insulator is bad.

You can also use a stethoscope to listen for the tell-tale "clicks" that an injector should make, but I've always had difficulty telling the difference between a working injector and the sound of a nearby injector spilling over.

 

lolz at the shock from bad insulators. at least then you know to get new wires soon too.
but im gonna ditto the plug wire method. easy simple and sometimes fun (BZZZT!!!)

 

yeah i noticed once that it's easier to shock oneself when pulling wires from the cap rather than from the plugs... on a car where it was not possible to run the engine while pulling the wires off the plugs b/c you had to take other parts off to get to the plugs. it kinda hurt after the fifteenth time or so

so def pull from the plug itself.

 

Thanks for the help. That makes sense and doesn't sound hard at all. And yes I have a 1991 Maxima and a 1999 Maxima, the 3rd gen is for winter driving.

 

Waiting for it, makes my day

At full rpm it takes full control of your clasped fist, u stay glued for the full thrill. Now u can figure out the cause of my full lobotomy...

 

Yes, that seems to be the manly way of doing it. But after I accidentally pulled to coil wire to the distributor on mine a few weeks ago (tracking down my own bad injector) I invested a few bucks in an insulated spark plug connector tool thingy. It also works for pulling from the distributer.

It was kind of cool wathing the lighting flash between my hand and various other metal parts nearby when I pulled the coil wire.

 

are you going to replace them all or just the one that is bad?

 

I think I just have one bad one. I have a parts car with six working injectors so if more than one needs replacing I will have extra.

So I pull the plugs with the car running or with the car off?

I also was reading that even with my parts car I will need to buy new gaskets and possibly new tubing also. I am guessing those parts are fairly inexpensive?

Thanks

 

I just bought the gaskets and o-rings and egr gasket from my local dealer last week. The lower intake gasket (Metal) was about $10.50, the upper plenum gasket (not metal) was about $8, the o-rings were about $3 for 2 sets (4 o-rings) and the egr gasket (I don't think I really needed this one) was about $3.

I didn't separate the throtle body from the upper plenum so I didn't replace those. I also didn't repalce the AAC valve gasket, since it seemed to be in perfect shape.

And your other question.. yes, you pull the spark plug wires lose (I did this at the distributer) and whichever one you can pull without the engine sounding worse is the one that is missing. Also, as mentioned above, you can use something as a stethascope to listen to the injectors. I use a 2 foot piece of fuel hose and stick one end in my ear and hold the other against each injector. If the injector is working, it will be a loud clear ticking sound. If it's not working, you may still hear a tick but it's more faint and is really coming through the fuel rail from another injector. It's pretty clear when you are listening to a good one.

 

Why didn't anyone suggest pulling the injector harness on the right side of the engine and checking resistance for the front three injectors, then pulling the individual plugs on the back three cylinders. It's actually pretty hard to tell a difference in engine performance when pulling plugs off while the engine is running. Plus if you pull the plugs while the engine is running the sparks can damage your ignition. Oh, and sticking fuel lines in your ear to hear if the injector is "clicking" only makes you look like a retard.

In other words, pulling out plugs while the car is running is dumb as hell. I personally can't believe so many people are recomending that you do that!!

The proper way to check for bad injectors is this: 3 screws will allow you to check the distributor for corrosion. Sand the corrosion off the little metal prongs and put the cap back on. Then, check each spark plug wire for resistance. Then, put the leads of a DMM on the prongs for each injector...the ones that don't read 10-14 ohms are bad. You might have more than one and not even know it. You can also check the injector wires to see if there's a bad connection.

 

you can always shut the engine off each time you pull a plug and then restart and examine how it runs

 

true...but that's so ANNOYING!

 

that's why most people don't do car work to the letter. they just wing it and refer to the book when they are totally lost.

 

noid light method. it WAS mentioned

 

Noid light only shows that a pulse (hopefully) signal is getting to the injector. It does not tell you anything beyond that.

 

what i did was simply clean all my injector terminals. then nearly a month later, bought some lucas fuel additive. put about HALF of it in my tank after filling up from dead empty. the next day, took her on I-95, and as soon as i got off i-95, clear as a whistle. no noticeable misfire.

that was nearly 3 weeks ago. still runnin smooth, as a matter of fact, better after i slapped the Short Ram on.

 

you are supposed to put the fuel additive into an empty tank tho so it mixes better.

 

Guess you then cannot be the same guy asking for help with a crappy performing motor after short ram installation ................... and then also don't even have the common decency to reply to/interact in your own thread

 

it was a mere vaccum leak. sorry.

but that thread was gettin a little off topic so i decided not to.

thanks man

 

I can believe that maybe pulling plug wires and sparking all over the place might not be a good idea, but are you saying that every mechanic (or do-it-wourselfer) who has used a piece of hose or an automotive stethoscope (a glorified piece of hose) for this purpose is a "retard"? I think this is pretty common practice for finding vacuum leaks and non-working injectors among other things that could be identified by the sound or absence of sound.