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Injector Knocking?

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preachermic

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Bostic, NC
I seem to have a knocking coming from my #4 injector. You can feel the vibration on the injector line. This seems to be only at idle or slightly above. When I use my GMTDScan software and turn that injector off the sound goes away. Would this be a good indication of a bad injector? My truck seems to run fine.
 
Would think so, try swapping that injector to another cyl and see if knock follows you could do for free. May also get you a feel for what your up against for Injector swap if you're a virgin. Good time to pick up injector socket nonetheless. We all should have one.
 
Injectors went in middle of February this year(2009) Truck runs good even at idle just rattling on the one injector. RPM's smooth, fuel equal on all injectors according to GMTD Scantech. Injector noise stops at about 800 - 900 rpm.
 
preachermic said:
Injectors went in middle of February this year(2009) Truck runs good even at idle just rattling on the one injector. RPM's smooth, fuel equal on all injectors according to GMTD Scantech. Injector noise stops at about 800 - 900 rpm.
Click to expand...

You getting a really really faint tink tink tink tink?

Becuase I get the same thing from turbo side 2nd one back(4? lol?)... I don't have scanner to shut down to confirm, but will be replaceing all injectors in a few months.
 
Yeah Matt, that's it. Sounds like a hollow tin can ringing. I've got a 3 foot long screwdriver I use as a stethascope and it is the only one that sounds like that.
 
I rebuilt the injectors myself that I was running before and had no problems. Then I started doubting my work and had another set "professionally" rebuilt and this is where I am at now.
 
pull the thing and poptest it.I bet the opening press is way to high.
now what is the reason you doubt your work?
just changing the nozzles,without pop test and matching shims wont do.
maybe you introduced a speck of dirt while installing them(can happen to anyone)
 
You could just have air in the line. Stupid question, but have you tried cracking the line while it is running to bleed off any air? I have heard it will tick with air trapped inside. Just a thought, good luck.
 
HMMMMM

All the lines will have the pulse feel to them.

Do this, with the engine running,wearing gloves, lay your hand palm down firmly on the metal turbo cover shield and see if the clinking sound goes away.

What I suspect is that the noise you are hearing is the injector closing sound (Clink) that is magnafied through the tubo tin cover.

These engine do this and when the squirts are new it can be quite anoying.

I passed up on a new GMC daully because I thought the sound was not right.

Some dont do it but most will.

Usually a faulty injector will make a hard knocking sound and not just a clinking noise.

Check it out.

MGW
 
Thanks Missy! When I pressed down on the heat shield the sound did diminish somewhat. So I started pressing and wiggling on the lines and suddenly the sound would go away. That got me to looking and one of the clamps had slipped and the line going to the supposedly noisy injector was touching the valve cover at one point. Shifted it slightly and suddenly no more noise. I really love all you folk here for your willingness to help when anyone has a problem. I give thanks for each and everyone of you each day.
Peace and Blessings - Mike
 
Argh, I've looked for rubbing, but never pressed down...outside me goes to the truck.... I think i'll install that starter brace now too
 
preachermic said:
Yeah Matt, that's it. Sounds like a hollow tin can ringing. I've got a 3 foot long screwdriver I use as a stethascope and it is the only one that sounds like that.
Click to expand...

I have that funny sound too. If I put a folded large towel over the turbo it is not audible. MGW is correct in her conclusion. I really hear it if I am along side a building or in an alley. I have lived with it for a long time. Oh, and I don't leave the towel there, diagnosis only---
 
I love it when a plan comes together.

So glad to hear that the issue was a simple little thing.

My 94 Burb makes a HELLUVA clatter sound with the higher pop pressure squirts in it.

The noise is the injector slamming shut as the pressure drops off at the end of the cycle.

When the turbo housing is clean and free of carbon and everything is spiffy these can be quite noisy.

MGW
 
For what it's worth, once I got the sound taken care of I took about 4" of 3/8" fuel line and split it and put it on all my injector lines and now all of the pinging and whatever is gone. With that along with the GL4 chip I put in a week ago my engine sounds totally tight. I pulled up to a friends place this afternoon and he asked: "What did you do to your truck? It sounds totally different."
 
:It would really be helpfull if some one would diagnose a sound properly ,saying knocking if it is really pinging makes quite a diff in what prob to look for.:nono:
But maybe i was asleep at the wheel.:rolleyes5:
 
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