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My Name: Arfur Dent

Guru
Posts: 3410
Joined: Sat Jul 23, 2011 3:47 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (52)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 100000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
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A post in the tips for a petrol would be a great place to detail how anyone could make their own petrol injector tester. It would be good to see it in action with some results too.
You can add an avatar to your account - Avatar or change your vehicle details - Car Bio or even add a signature to your posts - Signature. But this is not all you can do in the User Control Panel :)
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My Name: Ozvtr

Moderator
Posts: 1043
Joined: Wed Jul 10, 2019 3:31 am
Model: C3 2002-2005, Original shape model
Year: 2003 (53)
Engine Size: 1.4 (8v)
Fuel Type: Petrol
Mileage: 80000
Trim Level: Other
Gearbox: Automatic PRND
DPF: No
LHD or RHD: RHD
Engine name: TU3 (75 PS)
Location: Brisbane, Australia.
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Thanks for the comments. I'm never sure if there is anyone out there.

I'm not having much luck so far!
Connected it up to a battery, the display on the controller came on (yeah). Hit the switch for the fuel pump...nothing!
Pulled the box apart and found one of the solder joints on the switch was cold and had broken away.
tester 001.jpg
Soldered it back. Pump now works. But it seems to froth the fluid up quite a lot. I'm using mineral turpentine, Less volatile than petrol and it seems to be what they use in the professional injector testers.
Hooked up the injectors to the controller, selected a mode, hit start...again nothing! The display says it's pulsing. I hooked up my multimeter and I get about 4 Volts AC and about 2 Volts DC when it's on and nothing when it's off. Hmmm. I assume it's putting out a square wave pulses but I was expecting about 12V. Multi meters will only display RMS of a sine wave, you're on your own as far as the voltage readings of any other shape waveform. So a 4 Volt reading of a square wave means the voltage is probably about 5V peak to peak. 5V!!??
Ok lets open this thing up and have a look at the circuit
tester 002.jpg
What the heck? Yep it has 5V out! Why? It didn't say anything in the instructions! Only that it requires 12V in.
While I guess it's possible, I don't know of any injectors that would run on 5V!?
This is the second generation of the injector controller. You can see the first generation working on Youtube. The complaint they had about the first version was that you needed to disconnect it from the battery to reset it. It "locked" into one mode. This version has a reset button, so you don't need to disconnect it from the battery to change modes.
All is not lost. I should be able to move the injector positive supply wire from where it is, to the battery input positive connection. The transistor is switching the negative side.
It's set up to do one injector at a time but I will be running 4! I looked a t the specifications of the transistor and it will handle 8 Amps. The wiring looks heavy enough so it's only the PCB tracks that might burn out. But I'll risk it. :D
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My Name: Ozvtr

Moderator
Posts: 1043
Joined: Wed Jul 10, 2019 3:31 am
Model: C3 2002-2005, Original shape model
Year: 2003 (53)
Engine Size: 1.4 (8v)
Fuel Type: Petrol
Mileage: 80000
Trim Level: Other
Gearbox: Automatic PRND
DPF: No
LHD or RHD: RHD
Engine name: TU3 (75 PS)
Location: Brisbane, Australia.
Has thanked: 44 times
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Did I do something wrong in a former life and now I'm being punished for it?
tester 001 (2).jpg
I modified the circuit to run from the battery voltage and I beefed up the wiring around the output transistor.
I only tested the modified circuit on one injector and the output transistor went faulty! It outputs about 4VDC with the remaining 8V pulsing on top. The output from the driver chip is OK, so it's just the transistor.
Could I have done something wrong? Anything is possible I guess but studying the circuit shows it's pretty simple.
Now I have to wait for a replacement transistor to come from China! $#@*&!
User avatar
My Name: Ozvtr

Moderator
Posts: 1043
Joined: Wed Jul 10, 2019 3:31 am
Model: C3 2002-2005, Original shape model
Year: 2003 (53)
Engine Size: 1.4 (8v)
Fuel Type: Petrol
Mileage: 80000
Trim Level: Other
Gearbox: Automatic PRND
DPF: No
LHD or RHD: RHD
Engine name: TU3 (75 PS)
Location: Brisbane, Australia.
Has thanked: 44 times
Been thanked: 300 times

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Well I couldn't leave it alone could I?
The crazy readings I was getting from the circuit were bugging me.
Why was there a residual output voltage? Buggered transistor?
I removed the transistor...the residual is still there!! Well there is just the free-wheeling diode across the output. Remove the diode...residual gone!! $#@%! The transistor was OK but I destroyed it getting it off the PCB.
On virtually the first run the free-wheeling diode went "leaky" acting like a resistor. It's reverse biased to suppress negative surge voltages from the reactive load of the coils in the injectors. We can live without the diode.
So now I don't have a driver transistor and frankly I don't want to wait for one from China. What does my local electronics store have? The original was a darlington pair transistor. All that means is it has a high impedance input, so that there is no load on the little chip that's running the show. Hmmm a FET (Field Effect Transistor) would do as well. So I trundled down to the store and bought one (about 2 pound 50).
pcbmod.jpg
A long story short, I rebuild the PCB back to its original form. The 5V regulator is biased to output about 7V BUT it still wont drive the injectors. So I modify it back to running off battery volts (12V).
FINALLY, the injectors are clicking when I select modes on the injector controller!!!!!

So I put the injectors on the fuel rail, connect the harness to the injectors,connect the controller to the injector harness and connect the pump to the fuel rail. Connect the whole set up to the car battery and turn the pump on. After a few seconds the connection of the fuel tube to the outlet of the fuel pump starts spraying turpentine everywhere!!!!
spill.jpg
I took this pic after I had pulled the contraption apart and had cleaned up most of the mess!!
My postmortem revealed that the fuel pump had way too much pressure and volume for this little set-up!
So I added the fuel pressure gauge to the end of the fuel rail to monitor the pressure. I could only run the pump for a few seconds at a time before the system attained the correct pressure. The injectors are designed to run at 3 BAR. I estimate I took the system up to about 6 or 7 BAR before the joint gave out. OOPS I didn't think the pump was that powerful.
Wholesetup.jpg
Finally The thing begins to work the way I wanted it to (yeah). First up the injectors are not "atomizing" the liquid. It's being fired straight to the bottom of the measuring tubes (at great force I might add).
pattern.jpg
foaming.jpg
Second the injectors are well matched. Up to 50mls you can see they are within 1ml of each other. Oh, I must add these injectors are out of the "wrecker" C3 and as such are stock injectors. I am itching to see how the "cheap Chinese" injectors in my running car perform.
I don't know what the duty cycle of the driving pulses are so I don't know what the actual flow rate of the injectors is, but my setup gave a flow of about 13mls per minute.
levels.jpg
Well that was a bit of an anticlimax. It wasn't the pay off I was expecting for all the angst. It least it's working. I have a few more mods to make, like a fuel pressure regulator and a capacitor across the controller supply to stop the controller resetting when I turn the pump on/off.
But most of all I have to test the Chinese injectors now.
User avatar
My Name: Ozvtr

Moderator
Posts: 1043
Joined: Wed Jul 10, 2019 3:31 am
Model: C3 2002-2005, Original shape model
Year: 2003 (53)
Engine Size: 1.4 (8v)
Fuel Type: Petrol
Mileage: 80000
Trim Level: Other
Gearbox: Automatic PRND
DPF: No
LHD or RHD: RHD
Engine name: TU3 (75 PS)
Location: Brisbane, Australia.
Has thanked: 44 times
Been thanked: 300 times

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Well, I pulled the cheap Chinese Injectors (I think we've had enough of that joke now), the cheap injectors out of my C3 and put them in my injector tester.
I don't know whether to be happy or sad about the results.
levels 001.jpg
To make the picture clear, at the 50mls mark these injectors had a variance of about 3mls. When I did the flow test I got a flow rate of about 14mls per minute. To recap, the genuine injectors had a variance of about 1ml and the flow rate was 13mls per minute.
That puts the variance of the genuine at about 2% error and the cheap injectors at 6%. The engine ECU would probably average them out to 1% and 3%, respectively, across all 4 cylinders. As 2 of the cylinders were high and 2 were low, in both the tests.
So what does that mean? Well, it means the genuine and the cheap injectors were very close. Not perfect but (I would say) within any tolerances that might exist.
However the flow rate comes out about 8%. That's not as good, but, I am assuming that the genuine injectors are putting out the correct flow. That could skew the long term fuel trims and could send you on a "wild goose chase" if there was some OTHER problem with the engine?
Does this mean the engine would run differently on the cheap injectors? NO! The engine ECU would compensate. However the ECU would "say" it is using less fuel than the theoretical optimal amount for perfect components. Because each squirt of the injectors as actually putting in more fuel than the optimum perfect injector. So the ECU just "thinks" it needs to put less fuel in. The ECU still puts in the correct amount because it's monitoring the combustion products. It just "thinks" that amount is less than optimal.
Now I must point out that one of the cheap injectors (of the batches that I had bought) did fail. It developed misfires at highway speeds. So there may be a problem with reliability.
I am not going to recommend what the reader does if they need to replace their fuel injectors. But, with the cheap injectors being about 5 pound and genuine being about 50 pound I know what I would do (particularly seeing as I have a fuel injector tester LOL).
User avatar
My Name: Ozvtr

Moderator
Posts: 1043
Joined: Wed Jul 10, 2019 3:31 am
Model: C3 2002-2005, Original shape model
Year: 2003 (53)
Engine Size: 1.4 (8v)
Fuel Type: Petrol
Mileage: 80000
Trim Level: Other
Gearbox: Automatic PRND
DPF: No
LHD or RHD: RHD
Engine name: TU3 (75 PS)
Location: Brisbane, Australia.
Has thanked: 44 times
Been thanked: 300 times

Post

I don't know if you have seen my post over in the tips n hints area, but I've had a bit of trouble with the starter in my 1.4 petrol C3. It's been balking on start up and I thought it might be the carbon brushes in the motor. I did a tear down of the starter but I didn't really find anything wrong with it.
Well...now it stopped working all together.
So what did I think was wrong? well I suspected that the electrical contacts in the solenoid were burnt out, because, well there's not much left to fail! You might be tempted to think its a bad battery or the like but if I left the head lights on and attempted to start the engine, the lights remained bright, indicating no current was flowing through the motor.
As the solenoid is energized, it does two things, it pushes the pinion gear onto the flywheel/flexplate and also pushes a set of contacts to provide battery voltage to the actual starter motor. These contacts have a lot of current flowing through them and so they can get damaged. Oh by the way the contacts are buried inside the solenoid and cant be serviced.
I connected my multimeter to the point between the solenoid and the actual motor. There is a bit of exposed braid there to make it's easy to connect to.
starter1 018.jpg
The other side of the multimeter I hooked to battery negative.
negative pole.jpg
When I attempted to start the engine I could hear the solenoid kick in but there was only about 5 Volts across the motor. What was happening is the contact inside the solenoid had high resistance and was dropping about 7 Volts. This only left about 5 Volts across the motor, not enough to power it!
Here is a diagram of what's going on;
circuit.jpg
circuit.jpg (26.92 KiB) Viewed 23 times
Well to repair the starter will require a new solenoid. Hmp! Ebay here I come.
Meanwhile I'll dig out the starter from the "black wrecker C3".
WTF!! It's been changed too!!!
starter1 020.jpg
The OEM starter out of my C3 is on the left (Valeo) and the aftermarket starter (OEX) from the black C3 is on the right.
I have had three C3's and now all three have had bung starters!
Oh and if you saw the post, I warned that the locating dowel might not be supplied with an aftermarket starter. Guess what was missing from the starter out of the black C3? Yup, the dowel pin! It's so hard to get good help these days.

Well, anticlimactically, I put the aftermarket starter in and it worked.