Fuel Injectors question

[linkmrr]

That's a huge relief. Thank God I didn't listen to the idiots at autozone. There sitting in ISO heat + fuel injector cleaner which someone reputable told me to use.
AC delco 2173366 is factory correct? Or is there another I should use.

[crerus75]

I apologize in advance for the length of this post, but I want to put this information out there for others to use as well. Please bear with me.

I no longer have access to an injector part number database, as I no longer do fuel injection for a living. Also, GM and Rochester/Delco/Delphi used more than one part number for the same injector for our cars. If they appear to be the original injectors I wouldn't get too concerned about it, as you can go nuts trying to verify part numbers with GM. Check to make sure all the part numbers are the same and call it a day.

Check the coil resistance to make sure none of them have shorted internally, as this was a common problem with Multec 1 injectors. IIRC, resistance across the injector terminals should be in the 12 ohm range (double check this number in the service manual, or maybe someone can chime in). Anything close is probably OK (11.8, 12.2, etc.) Anything way low (about 9 ohms or less) is a sign that the winding insulation is breaking down and the injector will eventually fail. Way high usually means corrosion at the injector terminal causing excess resistance.

Double check the injector terminals for corrosion even if the resistance is within spec. This is not a problem with most injectors I've seen, but some cars (older Nissans, esp. 300ZX) are notorious for corroding injector terminals. Probably crappy seals on the engine wiring harness. Nevertheless, check to make sure no corrosion and use some silicone dielectric compound on each injector terminal when reconnecting the wiring harness. I use dielectric compound on every connection on the engine, including all the sensors. All it does is help keep moisture out.

Don't immerse the injectors completely if you're cleaning them. You need to keep any debris out of the inlet screens, and if you dunk them in a container of your favorite cleaner, all the gunk that's been growing on the outside of the injector since the car left the factory could get washed into the inlet. If you don't have injector cleaning equipment, the best thing you can do is to cap off the inlet somehow. Probably the best thing you can do is to seal the opening with a small square of duct tape. This allows you to remove the upper oring and clean the entire injector body without anything falling into the inlet.

MAKE SURE WHATEVER YOU USE TO CAP OFF THE INJECTOR IS SPOTLESS! I cannot stress how important cleanliness is when dealing with the inlet side of the injector, especially since you have no way to flow test the injector later. Clean the grime off the outside of each injector with a toothbrush and whatever cleaner you like. Simple Green works OK. Make sure whatever you use doesn't dissolve the glue on the duct tape, because if the tape falls off you no longer have any protection from contamination. Make sure you remove the orings and clean the oring grooves very well. Sand and grit get trapped here. Rinse off any cleaner and blow off with compressed air. Blow out the injector terminal very well. Do NOT blow air into the fuel inlet or through the injector! If you don't have compressed air, buy a roll of those blue shop paper towels. They seem to have less lint than regular paper towels.

To clean the pintle (outlet side), stand the injectors up in about a half-inch of Techron for a few minutes. Do not immerse the injectors in Techron! You want only enough to clean the pintle. This will not clean hard deposits, if there are any, but will remove the worst of the fuel varnish and carbon if there is any. Scrub GENTLY with a soft-bristled toothbrush. I don't know what cleaner you're using, but if it dissolves petroleum products (oil, etc.) it will probably work OK to remove any deposits on the pintle. Don't run out and buy Techron if what you're using is working for you.

Replace the orings with new ones before reinstalling. DON'T REUSE ORINGS! They roll on and off fairly easily, and they're available from almost any parts store. Buy enough for 9 injectors because you can nick or scratch an oring if you've never done this before. Make sure you've cleaned the fuel rail and the intake manifold before you reinstall the orings, otherwise all the crap on top of the engine will just fall into the intake and/or the fuel rail. Neither scenario is very good for the health of your engine.

I know I've given you a lot (too much?) to think about. Cleaning injectors is not a black art, nor is it difficult. The biggest mistake people (including some "professionals" who should know better) make is lack of cleanliness. It doesn't take much grit or debris to plug an inlet filter. From the moment you take the injectors out to the moment you put them back in, your most important job is to protect the injector inlet from debris. Short of smashing them with a hammer, nothing you do to the injectors while they're out of the car has the potential to cause as many problems as debris contamination.

(For those of you wondering, this applies to the entire fuel system-- one of the leading causes of fuel pump failure AFTER the pump has already been replaced is not due to a bad pump from the parts store, it's due to debris getting in the tank when you remove the sending unit to replace the pump.)

If you're wondering, places that do this sort of thing for a living keep their working environments well-lit and spotless, or at least they should. That means working surfaces that are non-porous and do not hide dirt, lint-free rags instead of paper towels, climate-controlled test conditions, filtered and dried shop air, etc. Cleaning injectors is not difficult but it IS meticulous. When you send an injector to a professional, you're paying them for their attention to detail, not for black magic. You're also paying them for their experience-- I was sometimes able to spot an injector that wasn't flowing right just by the sound the pintle made as it was cycling. It took hundreds of injectors for me to be able to do that.

[Philly9c1]

Originally Posted by Marky Dissod

$85 apiece?
FUNK DAT!

Bosch 'design 3' 28 lb/hr @ 43.5psi [LT4] Injectors $25 per inj
Bosch 'design 3' 25.8lb @ 43.5psi Injectors $24 per inj

Did u order from this website? If so, were they any good

[Carlton]

Originally Posted by crerus75

lots of good info

Thanks for that. Should you cycle the injector eletrically while cleaning them? Some people say yes, others say you can burn out the coils if you put voltage on them too long.

Originally Posted by Philly9c1

Did u order from this website? If so, were they any good

Got a set of their units on my Corvette, very happy with them. They don't 100% match the multec flows at all duty cycles, but it is within the ECM's ability to correct for (BLM will be off somewhat at lower rpm).

Lots of info on them at corvetteforum (eg. http://forums.corvetteforum.com/c4-t...up-within.html )

[crerus75]

Should you cycle the injector eletrically while cleaning them?

You won't burn out a saturated (high impedance) injector by cycling it unless you leave it powered on for a while (a LONG while). They are current-limited due to their relatively high resistance. For low impedance injectors, you can run a ballast resistor in line or run them at a reduced voltage.

Every commercial injector cleaning machine that I've seen cycles the injectors. This allows the cleaning solution to enter the valve area and the injector barrel.

[Marky Dissod]

Originally Posted by Philly9c1

Did u order from this website? If so, were they any good?

My only regret?
For those that can't/don't have the option of reprogramming, lesser options seem necessary, but I REALLY should've paid the extra $1 per injector.
Working just fine, even without reprogramming.