WBX fuel injector balance testing at home

[crazyvwvanman]

My recently installed wbx is running a little off. I decided to do a tuneup and check a few things. One thing I wanted to check was the fuel injectors, to see that they each sprayed a nice mist and all sprayed the same amount. I used some plastic graduated beakers I got on Ebay.

1. remove the screw on each side of the engine which holds the injector pairs in the manifold. Pull out the injector pairs.
2. pull the center wire out of the distributor cap and set the loose end on engine metal
3. remove distributor cap, rotate engine till the pulley timing marks line up AND the rotor points to the #1 mark of the distributor edge.
4. loosen the 13mm nut that holds down the distributor clamp bracket to the block. Leave the nut on just a couple threads.
5. lift up the distributor slightly and make sure the rotor now turns with your fingers.
6. turn on the key but don't crank the starter.
7. rotate the rotor by hand and you should hear the fuel pump run and see the injectors spray for each 1/4 turn of the rotor. there should also be a spark from the loose wire end for each 1/4 turn. careful!
8. place a test tube under each injector on one side of the engine
9. use a finger to quickly turn the rotor, counting full turns as you go. I did 30 turns, then stop.
10. look at the 2 test tubes and see how much fuel is in each
11. do the other injector pair the same way, same number of rotor turns
12. compare the 4 test tubes, hopefully the same amount of fuel is in each

13. turn the rotor till it points at the mark on the distributor edge
14. push the distributor back down into place while rocking the rotor to make sure it engages fully into place. tighten the 13mm nut
15. put back the injectors and screws
16. put back the dizzy cap and center lead

Mark

[the joker]

good plan well thoughtout decent amount results..... but it also has to do with the uniform spray pattern bently has a procedure check it out


I personal don't deal with fuel inj my westy has a single factory carb set up
keeps thing real simple no ecu no multi fuel line to maintain no injectors to worry about good luck and always keep a fire ext handy

[crazyvwvanman]

Yep.

[crazyvwvanman]

Reminder of thread with a way to test the Digifant injector spray.
This also tests the distributor hall, ignition coil, FI relays, ECU

The test showed 30 finger tip rotations of the distributor sprayed about 2ml of fuel per injector. If anyone does the same test please share the amount of fuel measured.

Mark

[DanHoug]

i like the simplicity of your test and that all components are worked.

i've gone to a test rig for cleaning (naptha/Coleman fuel) and patterning activated by an inexpensive buzz box where i spliced on 4 injector leads and the drivers of the box handle 4 at once just fine. my volume measurements are meaningless to your query but info offered as a curiousity of process.

_________________
-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[SyncroHead]

[SyncroHead]

I completed the fuel injector testing with Mark’s (crazyvwvanman) procedure outlined above. I’ll add that this procedure is a genius-level Vanagon hack. It allows the testing with:
- No use of starter motor or having the engine turn over at all
- Precise and repeatable measurement of the number of injection pulses, instead of by a clock attempting to crank the engine for XX seconds
- No disruption of any of the system adjustments including timing
- The fuel spray is tightly contained in a cylinder sized almost as if it were meant to have a Vanagon fuel injector inserted. No jar or other cumbersome container.
- Completely do-able with just one person
- Easy to repeat testing if desired

To reduce the error potentially induced by reading the level of the cylinder, I did exactly 2X (60) the number of rotor turns compared to Mark’s initial testing (30).

I used these graduated cylinders from Ebay, FOUR for just $15 including shipping. I’d intended to buy plastic ones for the durability, but these really nice glass ones were so cheap, I couldn’t turn them down.
https://www.ebay.com/itm/KIMBLE-10-ML-GRADUATED-CY...2749.l2649

To hold them in place and protect them while doing the test, I made a pair of jigs to hold them in place using some cutting board material and mirror mounting clips.

With 4 of them in two pairs I was able to test all four injectors simultaneously. My initial test showed little or no flow to cylinder #2 and thought I may have found reason for my van’s drivability issues. Turns out I just had not attached the in injector’s electrical connector completely. A retest using only this cylinder was very easy and confirmed OK flow.

Here’s Mark’s procedure with some photos and comments:


1. Remove the screw on each side of the engine which holds the injector pairs in the manifold. Pull out the injector pairs.
Jim: It looked pretty dirty and I didn’t want to risk getting debris in the injector hole, so I’d recommend blowing these out with air first if you can.

2. Pull the center wire out of the distributor cap and set the loose end on engine metal

Jim: I didn't have a good way to hold this wire to ground, so I installed a stud into an open threaded hole on the top of the cylinder #3, and wrapped some wire around it and bent the end of the wire so it formed a “post” to attach the coil wire.

3. Remove distributor cap, rotate engine till the pulley timing marks line up AND the rotor points to the #1 mark of the distributor edge.

4. Loosen the 13mm nut that holds down the distributor clamp bracket to the block. Leave the nut on just a couple threads.

5. Lift up the distributor slightly and make sure the rotor now turns with your fingers.

6. Turn on the key but don't crank the starter.

7. Rotate the rotor by hand and you should hear the fuel pump run and see the injectors spray for each 1/4 turn of the rotor. there should also be a spark from the loose wire end for each 1/4 turn. careful!
Jim: My coil wire was securely grounded, so no sparks.

8. Place a test tube under each injector on one side of the engine
Jim: I did both sides simultaneously.

Jim: With the test jigs inserted below the fuel injectors, the spring tension in the fuel lines holds them in place very nicely. The space between the injectors is almost exactly the space between the cylinders when jigged close together.

9. Use a finger to quickly turn the rotor, counting full turns as you go. I did 30 turns, then stop.
Jim: I did 60 turns to be easily comparable to Mark’s 30 turns.

10. Look at the 2 test tubes and see how much fuel is in each
Jim: Initial test:

Jim: After finding injector #2 connector was not properly connected...
Re-test . with just cylinder #2

11. Do the other injector pair the same way, same number of rotor turns

12. Compare the 4 test tubes, hopefully the same amount of fuel is in each

Jim’s Results:
Cyl 1: 4.8ml
Cyl 2: 4.8ml
Cyl 3: 4.7ml
Cyl 4: 4.7ml
Sorry, the cylinder side facing the camera has the graduations marked from top to bottom, so reading from this side one needs to count back from 10ml. The other side has the graduations marked from bottom to top.

Next up for testing, the Marco Mansi injectors:

Photo before I realized I'd put the injector holding brackets on upside-down:

Of course the new fuel lines won’t make a difference, that was just maintenance, but I wanted to see how the Marco injectors performed. While the original injectors all provided a decent “spray” and none were squirting, the Marco injectors did appear to have a finer mist. Can’t exactly measure this, but I can measure the flow.

Here’s the cylinders after the Marco injector testing, with same 60 rotor turns.

Cyl 1: 5.7ml
Cyl 2: 5.8ml
Cyl 3: 5.5ml
Cyl 4: 5.8ml


Observations:
The Marco injectors I tested definitely showed more fuel flow than the originals. I have no way of knowing how many miles are on the original injectors. They are the green color injectors without the VW part number on them, so they are NOT original from the factory.

The average of the Marco injectors (5.7ml) was 20% greater than the average of the original injectors (4.75ml). Oddly, the Marco injectors showed greater variability from one injector to another. If I were really dedicated, I would have run this test several times with each set of injectors, but seems I’m more of a slacker.

The Marco injectors with the new fuel lines and fuel rails.

Results:
My van still has a drivability ("missing") issue, especially when cold and mostly around 2,000-3,000 RPM, and an idle stability issue. The installation of the Marco injectors has seemed to increase power, but I look forward to the day when I track down and solve the "missing" issue. This post is NOT about the issues with my van, so I'm not soliciting any advice on that here.

I want to recommend crazyvwvanman's procedure, amplify on it a bit, add some pics, and relay my experiences.

Thanks Mark!!

Hope this is useful!

Jim Davis
_________________
"A Vanagon? It's not a car or a van. It's a hobby!"

Check out:
www.VANAVATION.com
www.SyncroSafari.org and
www.Vanagons.org

[4Gears4Tires]

In order to cheaply clean the idunnoprobably30 fuel injectors I had laying about, I created a small rig to easily clean them all. I took a wheel valve stem, removed the shrader valve, and drilled a small hole the size of a carb cleaner red tube in the cap. I super glued the red tube to the cap and then screwed the cap back on the valve stem.

Important to note: The valve stem is a tight fit over injectors, but it is not permanent for high pressure. Wear a face mask!

Then, with some stacking of items so that the injector is at the same height as a can of carb cleaner, I inserted the red tube into the can, with the valve stem over an injector. Using a jump pack for power, I connected 1 alligator clip to ground and 1 to power. I attached ground to the injector and left power unclipped on the injector side. Then, (and this took some practice) I quickly tapped power to the injector while pushing down on the carb cleaner top. If you go out of sync, it blows apart. If you get it synced up, you will see the pattern go from ugly to pretty with 5-10 bursts. It's important to tap power quickly because injectors are not built to hold sustained power, they will burn out.

This is also a great way to see which injectors are straight dead. They won't click.

Is this as good as an ultrasonic bath and whatever else real injector refurbishing services do? Probably not. But it was effective for what I had laying around.
_________________
'87 Syncro
Ferric Oxyhydroxide Superleggera Edition

[Sodo]

Cool test.

Here's a test tool I made for cleaning Subaru EJ25 injectors.
I pressurize the tube with my mouth and blow carb cleaner thru the injector.
Note a 9v battery can operate the solenoid valve (on Subaru injectors).
_________________


'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[DigiMatrix]

I do see one fault in the op's test when comparing one set of readings to another. The amount of time the injectors pulse is a function of RPM, ect, iat, acceleration, etc.. Rotating the distributor at different rates will give different flow rates as does performing the test at different ambient temperatures. For ensuring equal flow rates between 4 injectors the method is fine. However testing at different times isn't. Might I suggest putting 2x Marco injectors and 2x original and then perform the test. This way the results will be apples to apples.

[DigiMatrix]

Another thought to simplify the OP's method. Get spare Distributor, unplug the Hall sensor on the one in engine block and connect it to the spare. No need to mess with timing marks or lift the existing distributor. Follow all other steps, but you can rotate the distributor gear if you like. Once done, re-connect the Hall plug to the original distributor - timing is still intact to the value set before the test.
_________________
_________________
'91 Syncro Westfalia
soon to be 2.5 liter stroker WBX 10:1 comp
Digifant ECU with knock sensor and custom
cylinder selective knock control by me