fuel injectors

[Elessee]

Having saved about $800 by replacing a heater core myself, I be feelin' my oats and decided to take on the injectors.

Top pic is the injector ports. Carbon is trying to close off all the ports. As much carbon as there is now, much of it in the ports' centers must have broken off and fallen into the manifold when the injectors were wiggled out of there.
Maybe the sheer force of injector spray is all that keeps the ports open.
There's no way these injectors can be spraying a nice conical pattern, even if they were immaculately clean internally.

The wetness around most of the 8 ports cannot be oil, or just oil. Some of it has to be fuel leaking past an injector O-ring.
Second pic is an attempt to show an intake valve with an inspection camera, snaked into an injector port. Not enough light to clearly illustrate how bad it is [Edit= found some more light, and replaced pic with this one] ...mountains of carbon all the way around the valve seat area. (Combustion chamber would be to the right.)

 

[chris2523]

wow. that is dirty.

 

[Elessee]

"...wow. that is dirty. "
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I thought so too, until a couple minutes ago. Actually, mine aint that bad inside, which is all I care about atm.

Search google for "intake valve cleaning" and the third link from the top is
"DIY-Intake Valve Cleaning - BMW 3-Series (E90 E92) Forum - E90Post.com"

That thread has lots of good pics. The guy's car has only 50K miles.
He pulled the intake manifold and then cleaned the intake valves through the ports' holes. Started by spraying Chemtool B-12 (what I was thinking) and let it soak for 30 min.

I think he practically filled the ports with cleaning fluid (see pics for why.. they are cruddy), turning the crank so each valve was closed in turn, to avoid filling the cylinders with all the crap. Then sucked it out with a vacuum attachment.
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If this were a Chevy small block, I'd probably have the heads off already, but I never worked on ford stuff. Exhaust valves, combustion chambers, cylinder ridges and piston crowns gotta be all carbon'ed up too.

But all I want to do is get these injectors working as they should, put it back together and pass smog. The wet crud outside has to be due to some fuel leaking up there, which can't be good. Going out to buy a set of injector O-rings and cleaning supplies now.

One weirdness is that cylinder 8 (driver's side, rear) is the only clean one. Not much exterior dirt, the injector port is clean, and the intake valve is clean. Wonder why..

 

[Elessee]

This is one way to get some solvent (Chemtool B-12 Fuel Treatment) into the injectors. At first, interior air prevents fluid entry, and some pressure is required.
Even after the interior "air bubble" has been displaced by fluid, it won't flow out by gravity, so some pressure is needed.
[Edit- Some of these injectors will flow by gravity alone, some won't and may be clogged.]

I tried a turkey baster stuck in the tubing, and it works.
With an eyedropper or pipette, put about 1 ml of fluid in the tube. Attach baster. Power the injector on, squeeze baster a little, and turn it off. Let it soak in there.
A fast on-off switching will sorta pump some fluid through. (edit- this happened only once, to one injector, and never again.)

Can't see it in the pic even against the white paper background, but after about 30 min, and another dose, the waste fluid at the bottom of the jar has acquired a definite brownish tint, while new fluid is water clear. So, at least something is happening.

This power supply is convenient, but any 12V DC source (battery) will do. Far as I know, there's just a simple coil inside (electromagnet)... no diodes.. no nothing. According to my research, an injector draws about 900ma (just less than an amp). My power supply shows 780 ma. So, whatever the power source, it must be able to supply at least that... roughly 12 watts per injector (1A x 12V = 12W)
[Edit- Not necessarily true for other cars. There are 2 basic types of coils, low and high resistance... low, around 5 ohms and high, around 16 ohms. These are "high".]
Solenoid duty cycle is unknown, but one YouTube cleaning vid shows constant activation and apparently no ill effects, and my guess is injectors are rated at 100%. (A 50% duty cycle means a device, like a coil or electric motor, can only be safely powered on for, say 1 minute, and then must be turned off (to cool) for 1 minute.)

At $200 a pop for these things, I gotta admit to being a bit nervous at first..

 

[Elessee]

There's no need for the turkey baster. Just close the tube with an index finger and squeeze tube with thumb and middle.
A spring-type hose clip provides a good seal at the hose connection to the injector. If using the 5/8"-exterior tubing, an appropriate spring clip is on the small (5/8") vacuum hose in front of the upper manifold (which must be removed to get this far anyway).

The injectors were put in an ultrasonic jewelry cleaner for about 30 minutes, with dish detergent and distilled water. Lots of exterior crud came off but I doubt it helped the insides.
Every ultrasonic cleaning method I saw energizes the injector to open it's port, cycled it open with a quick pulse circuit, and ran for like 30 minutes or more while submerged, and I didn't wanna mess with that.

This cleaning process was running ~ one ml. of cleaner through them, and soaking for a while. These injectors can hold about 1/2 ml. in the interior.

At first a few didn't drip at all by gravity alone, and needed slight pressure to flow while energized. After three cleanings, all dripped about one drop per second or two without pressure. I dunno if that means anything or not. The final cleaning showed much cleaner solvent collecting in the jar, but not perfectly water-clear.

I ran a primitive leak test using a bicycle pump and a hose, estimate about 15 psi. None of them showed air leakage under water. Since air molecules are very tiny, chances are none are dripping fuel under full pressure.. but it's just a guess.

Fuel rail and manifold O-rings are another story. Some pulled out easily, and some were really difficult. The "easy" ones are leakage suspects in my opinion, and all were at the manifold end of the injectors. Rebuild kit included the 2 O-rings, the pintle cap and the plastic washer @ $32 for 8 kits. No filter screen included, but visual inspection shows nothing wrong with these. Screen removal requires a tool similar to a small slide-hammer with a screw end, and will damage the pressed-in screen. There's little point in back-flushing unless the screens are removed.
That's it for these injectors, for now anyway..

Next is to clean the injector ports in the manifold, clean up the exterior manifold and valve covers, and reassemble everything. Solvent was sprayed into those ports and should soften some of that carbon around the valves by the time this thing gets running again.

odds and ends..
Solvent melted blue nitril gloves... eye protection at all times.. keep an extinguisher near by.
All the coils showed 16 ohms, and all drew 780 milliamps @ 12.6V. I saw one guy who tested / energized them with a little 9 volt battery, btw.
OEM injectors are Bosch E6TE-A2B and are #19s .. meaning they flow about 19 pounds of fuel per hour wide open @32PSI. Small compared to some, but times-8 and you can get some horsepower IF the engine can burn all that fuel. These are stock for four years (87-90?) in Mustangs and Marks and at least one BMW (?) or some other import. New $200, rebuilt's are $50.
Remove the protective plastic pintle cap (old ones will undoubtedly crack apart), and see a tiny little pin sticking out. That pin does not move. Protect that end of the injector at all times.
Solvent removed their black paint, but they have a weak magnetic attraction so I think it's a high nickle stainless steel alloy. I dunno about repainting mine or not... Not is most likely.

 

[Elessee]

First thing was to just turn the key to RUN and off, and to Run a few times, which activates the fuel pump and fills the rail. Then check the fuel rail for any leaks.
No leaks.
Started the engine and idled for a minute.. No coolant leaks.. no fuel leaks. The idle speed is much lower than before. I shut it down and will do a test-run tomorrow.

I read somewhere that the engine's computer has a persistent memory, and requires a few running cycles before it can readjust to any new operating conditions (like a massive, thorough tuneup). Anyone know something about this?