How do you "pulse" the injectors during cleaning???

cjpacitto · 07-01-2009, 06:11 PM

When cleaning fuel injectors, how do you go about making them "pulse"?

My car has 150k+++ miles on it and I don't believe the injectors have ever been cleaned. I currently have them out of the car to replace the air/oil separator (AOS) seals and associated vaccum hoses so it seems like a perfect time.

I have read the article on this on the "Tech Info Center" portion of this site. It referrs to using a 2 mV battery charger to do this. What is a 2 mV battery charger? This does not seem to be a standard automobile battery charger, is that correct? A quick google search did not turn up any real useful info.

Clark's Garage indicates that these are low resistance (3.5 ohm) injectors. As such, connecting them directly to a 12v battery would result in a roughly 3.4 amp current being drawn. I have been told that 3.4 amps will cause damage to the injector.

Does anyone have more specific info on what kind of arrangement should be used for this? I think I could use a resistor (maybe a small marker light bulb) in line between the battery and injector to reduce the amperage. However, I don't know how much amperage is acceptable through the injectors and don't want to learn by screwing one up.

Can anyone help?

Thanks,

SuperXRAY · 07-01-2009, 08:23 PM

Well, I'm not sure I even want to dwell into this, but it sounds like you need to just send them off to WitchHunter:

WitchHunter WebSite

If you are dead set on cleaning them yourself, you will need a pressure rig (my preference, anyways), new seals/hats, good injector cleaner, computer power supply, a momentary (normally open) switch, and the knowledge to not light your garage on fire.

Here are some photos from a 2004 Dodge Grand Caravan SXT that I recently worked on...we ended up replacing 5 of the 6 injectors, as the one in the last picture was the only one that had a good spray pattern. The rest simply shot a stream out. However, those injectors are $40/ea, as opposed to the huge price for the 944 injectors.

Air host Adapter:

All the injectors coupled. The 944 assembly is pretty much the same, except there's only 4!

After-cleaning spray pattern. I couldn't take one before, as the photographer wasn't home and timing the camera and the injector together is tricky:

Please note. These injectors WERE backflushed, but without pressure, which probably has minimal results. They all sprayed somewhat better after backflushing and forward pressure cleaning, but the van still only got 18-19 mpg. After replacing 5 of the 6 injectors with Borg-Warner Injectors, it got 23 mpg. They were hooked up to the 5v circuit on the power supply, which is good for showing failures and inconsistencies on some cars. I had to up it to 9v at 35psi so they would actually fire, which is what the van was rated to run at. Without a timing circuit to control the duty-cycle, I would not go over 9v unless it is for a VERY short amount time. Injectors fire in milliseconds, and 12v on a 944 injector will ruin it in just a couple seconds.

BTW, resistors in electronic circuits reduce voltage, not amps.

cjpacitto · 07-02-2009, 03:06 AM

Quote:

Originally Posted by SuperXRAY

BTW, resistors in electronic circuits reduce voltage, not amps.

Actually, it is both. V=ir so "total resistance" of the simple circuit will determine the amperage going through the entire circuit. Each individual resistor the current goes through will then reduce the voltage. You are right though. If designed right I can get both the voltage and current down at the injector.

I have seen Witchhunter before as well as some other cleaning services. This car is not a daily driver for me, it is a project car. The whole idea of the project is doing things myself. If I fail then I'll consider sending them out, but for now I plan on doing it myself.

914efi · 07-02-2009, 04:38 AM

I connected one of the wires I was using to bench power the injector to a threaded rod and then the other to a probe that I ran down the rod. As it bumps over the threads it 'pulses' the injector. Kind of crude, but works.

SuperXRAY · 07-02-2009, 09:19 AM

Quote:

Originally Posted by cjpacitto

Actually, it is both. V=ir so "total resistance" of the simple circuit will determine the amperage going through the entire circuit.

OK, have at it. I'm...anyways, good luck.

v2rocket_aka944 · 07-02-2009, 12:32 PM

12v drill battery with alligator clips works fine

no issues on my injectors since doing this to flush them with brake cleaner in 05

cjpacitto · 07-02-2009, 05:53 PM

Thanks V2!

My cordless drill is an 18v so I didn't want to try that. Instead I tried a 9v household battery (like from a smoke detector) and it worked great. I pulsed it on and off and it worked fine. I did not try holding it open for any length of time.

I tried adding a small marker light bulb in the circuit and the bulb lit but the injector did not open.

With some short pieces of 1/4" ID and 3/8" ID hose, and a couple quick connect compressor fittings I was able to flush the injector from both sides.

Does anyone know what the best solvent is to use? I have been using throttle body cleaner. Would there be any point to trying the "fuel additive" injector cleaner they sell at the auto parts store?

SuperXRAY · 07-02-2009, 08:02 PM

I used SeaFoam, but make sure you don't just leave it in there. I filled the fuel rail up with SeaFoam for the forward flush, and went from the highest injector to the lowest, because that's how the fluid flows.

Gravity, you know. Was quite easy. SeaFoam is pretty powerful stuff, so make sure you don't leave it for any length of time.

SolReaver · 07-03-2009, 08:49 AM

I would suggest a 9v little battery with the clip and the leads. 9v is low enough that you don,t have to worry about over powering the injector. Remember to replace those little seals and think about replacing the rubber lines WYAIT. a good soaking in carb cleaner overnight and blowing out with compressed air while pulsing should get most of the crustaceous buildup. WH is the way to go for a thourough cleaning (ultrasonic) and flow matching. A lot of so called injector problems are actually something else, so, check the FP, Bypass, signal, etc...IOW the usual suspects. Injectors can be swapped to determine if it is an injector or another component.