G'day

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.

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. 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 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.

Did I do something wrong in a former life and now I'm being punished for it? 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! $#@*&!

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).
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!!!!
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.
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).
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.
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.

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.
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).

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.
The other side of the multimeter I hooked to battery negative.
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;
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!!!
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.

Well summer is on the way and the air conditioning in the C3 is still leaking refrigerant @#$%!

When I did the cylinder head gasket I also replaced the aircon components in the engine bay. When I did the dash replacement I inspected the evaporator and decided the evaporator looked OK, No corrosion and plenty of oil. Meaning the thermal expansion valve in the evaporator looked good and having plenty of oil, it was unlikely to be stuck. So I left it in the air distribution box.
When I disassembled the "black" C3 I was sure that there was still refrigerant in the aircon system. Well, I was sure that there was pressure in the system. Of course I had no way of knowing how much refrigerant was actually in the system. This will become important in a moment.
Just to recap, since I got the car the aircon has leaked refrigerant. There was oil on the joints of the compressor seals and on the compressor in general. I pulled the compressor apart but it had a lot of corrosion and cleaning it up didn't seem to work. So I decided to change all (most) of aircon parts when I did the head gasket, as I believed that system in the black C3 was good (I.E. holding pressure).
In the engine bay, the aircon consists of one long high pressure (small diameter aluminium tube) that goes from the condenser in the front of the car, around the engine bay to the evaporator at the fire wall. The low pressure (large diameter) line that also goes from the evaporator at the fire wall to the compressor. A small high pressure line that goes from the compressor to the condenser. The compressor and the condenser. So that's everything except the evaporator in the cabin.
Ok, so at this point in time (after replacing the components and we are now in the present) the aircon is still leaking.
In the air conditioning system there is oil. This oil is to lubricate the compressor, which is basically a pump. A complicated pump that needs oil. When running, the air conditioning refrigerant picks up some of this oil and distributes it around the system. The theory is that if you have a refrigerant leak some of this oil comes out of the system with the refrigerant. Meaning that you just need to look for the residual oil if you have a refrigerant leak. But as I said...theoretically! If you have been following this (blog?) you will know that I had a leak in the "other" C3 and that the hole was substantial but no oil came out!!! Well an inspection of this aircon system showed no oil leaks either. OK, so what now? Well the next option is to pressurize the system and use soapy water to see if it forms any bubles. So I filled a spray bottle with a solution of dish washing liquid and water. Then squirted it around the aircon components. The only thing I could find was a tiny leak in the flexible hose of the low pressure line to the compressor. On inspection there was a small chunk of the rubber line that had been taken out. It looked like the spinning pulley of the compressor clutch had come in contact with the rubber line at some point and worn away some of the rubber. Remember this line is from the black C3 and this damage might have occured in the accident. The rubber lines run under the compressor but very close to the pulley. The leak was very tiny but there were bubbles forming there! So the line needs to come out.
Oh, boy! Pulling all this stuff out with the cylinder head off and the front bumper removed was easy, but now with the car in one piece? Well don't just stand there...get to it!
I removed the inlet manifold, coil pack, injector rail and all the ancillery bits associated with that stuff on the engine to gain access to the a/c lines at the firewall. Jacked the car up. Removed the driver side road wheel, wheel arch liner, bumper retaining fasteners, headlight and washer bottle retaining fasteners. Disconnected the low pressure line at the compressor and firewall. There were a couple of plastic clips holding the high and low pressure lines around the engine bay. It wasn't fun but with some finagling, I got the low pressure line out.
I had no choice but to put the original low pressure line back in. I inspected it and it seemed in a serviceable condition.
If you have been paying attention you will know that I actually pulled this line out at one stage, suspecting that it had a leak! I think (hope) that using the gas detector on the rubber lines may have been flawed and the rubber was giving a false positive indication of a leak. I postulate that the rubber is slightly permeable and the detector was too sensitive. Time will tell.
Putting it back into the car was no easier than getting the other one out. But I got it in.

The low pressure line;
Inspection of the low pressure line flexible joint showed a small nick in the surface of the rubber down to, what looked like, another layer of the the rubber hose. It seemed to be leaking where this layer was exposed.
Did changing the line stop the leak? Well initially I didn't think so. The pressure seemed to be going down, indicating a leak (still). However, I didn't seem to get a full charge into the system and there is a thing called vapor pressure. Basically, vapor pressure means as the outside temperature goes up and down so does the pressure inside the system. As the outside temperature got cooler the pressure in the system went down too. Making it look like the system was leaking. I am still skeptical that I have found the (only) leak! But I will give it a couple of days and see what has happened. As the saying goes; a watch pot never boils!

Now most air conditioning system tend to leak. They are not engineered to leak, meaning that they shouldn't leak at all, but they can develop leaks anyway. Typically, an acceptable leak (worst case) requires the system to be "topped up" every "couple of years". Considering the lifespan of an average car and the cost of "topping up" Vs repairing the system, topping it up seems to be acceptable. However with the price of refrigerant going up, topping up a "leaky" system over the lifespan of the car might not make economic sense. Better to just get it repaired. Then there is the Global Warming Potential of the refrigerant to think about too.

It's a bit quiet on the forum ATM.

Yeah! My starter solenoid arrived from Latvia, half way around the world! Yes, I don't get out much. It cost me about 40 euros, that's about 80 Aussie bucks (or dollarydoos).
Some of you are thinking that I could probably have bought a whole second hand starter! But where would the fun be in that?

I have pulled the starter apart...well as far as I can at the moment. The planetary gearbox is sealed up in the motor casing and I can't find a way to get in. But I'll keep persisting.
On ebay I found the solenoid, the armature (the spinny bit of the motor) and the carbon brushes for sale. If one thing were to go wrong the starter is economical to fix, but buying more than 2 bits might not be worth it. A new aftermarket starter might be more economical.
I will probably update the starter teardown that I did with some new pics. I'll either replace or supplement the pics.

I have replaced the schrader valves in the airconditioning service ports. They look like bicycle tyre valves and allow refrigerant in and seal off the system. I found a dribble of oil and dye down the sides of the service ports indicating that the schrader valves were not properly sealing. Both you and I are getting a bit tired of hearing this! I have fully filled the system, so we will see what happens? Oh, if you are worried about me leaking R134a into the atmosphere and contributing to global warming...I'm not. I'll just say there are alternatives to R134a.

Engine seems to be "drinking" small quantities of coolant. The level in the expansion tank seems to be going down, very slowly but it's noticeable. It's possible that the head or block are warped. The engine seemed OK and didn't show any signs of over heating. If one spark plug comes out cleaner than the others when I do the next service, it's possible the new head gasket is leaking and coolant is getting into a cylinder. Hmmm another thing to keep an eye on?

Other than that the little car is running well and the auto gearbox is behaving itself. When fully charged, the aircon does quite well against the Aussie sun! Let's see how long it lasts?

Just a quick update.
The coolant level is not going down! I don't know what happened but the level is now remaining static!
Engine is still VERY "tappety" on start up but sounds fine when warmed up. I have checked the inlet and exhaust valve clearances and they are in spec. Seems to be around the No1 inlet valve but its hard to tell.
The aircon is working fine...so far. I set the climate control to 21'C and it's quite comfortable against the 36' or so, outside temperatures.
Unfortunately there is no way to test how much refrigerant is in the system. The usual way you can tell if the aircon is low on refrigerant is if the compressor becomes noisy and/or you can here the system "hissing" in behind the dash. The system can still produce cold air right up to the end. Typically the system pressure gets too low and the compressor won't kick in. Still seems to be OK so far.
Oh! I need to adjust the accessory drive belt tensioner as the belt sequels when I turn the aircon on! It's the old school manual type tensioner.
When coming off the highway onto the off ramp, the change down from 4th to 3rd is a bit clunky! Around town it's fine. 3rd gear is way too tall for the 1.4i engine. In 3rd around town the engine is doing 3K RPM but 4th drops the revs down to 1.5K and the response is too "boggy".

Nope! Compressor has become noisy so I checked the line pressures. They were down. Yep still leaking! But I have some sort-of good news, I found the leak. It's in the "low side" line. It's the crimped join between the fixed lined to the compressor and the flexible line back to the evaporator. It's not broken, the crimped area is not forming a seal. That's bubbles from a dish washing liquid and water mixture. The gas detector found it and the bubbles confirmed it. Now, how do I fix it?



Well summer is here! Actually it was only 37' in the shade!