Hey there,

so, I've fbeen doing my injectors today. The hoses were removed quickly after knowing the best way to get them off. So I built myself a "test bed" with my "injector cleaner" from Liqui Moly.

I used two glass yoghurt pots, one with a car tire valve, and a hose from the bottom. The other with a hole in the top for the injector to sit in. The fluid was in the first glass. After pressurizing the top, it would force the fluid through the hose into the injector. The injector had a plug on top wired to the battery. A "pulse" of the car ECU was simulated via simply touching the battery terminal.

So, first off: the cleaning agent/fluid is not as "thin" as petrol. It is about a middle thing between water and petrol... I didn't expect to get a "squirt" like the injectors would on petrol. Instead all injectors work and have the same style "jet":

1st: when initially started, it squirts once like a normal injector would
2nd: when the fluid reaches the injector the vaporisation turns to a "jet" or spout
3rd: the pressure I had was around 1 Bar (lowest 0.5 Bar)

Here is a quick video of how the result looked ALL the time... All 12 injectors had the same "pattern" (this is as said all the cleaning fluid stuff):


I'll be trying this later on again (in a few days time) with pure petrol, as the cleaner is currently still in the injectors. As they are all even from their jet-look, I assume they will all work perfectly on petrol with a higher pressure... Just got to see how I can make more pressure...

 

Fuel injector cleaning rig.

Right?

 

all well and good , BUT how much liquid does each injector flow CC in,say 1 minute time, accurate ly? using the same Pulse width time.

they should flow within 3% of each other!

OK just say the engine cylinder only needs 20cc per minute to idle properly(just say for example).
the injectors need to flow 300cc per minute at full throttle!

so you would not need more than 20cc idle,runs perfect,up to cruise 100cc, still runs very good(everybody is happy right), but a full output engine needs the 300cc!

what if 10 injectors flow 300, one flow 280cc, and one flows 225cc, all with same fuel pressure, . and PW.
question ;what cylinder would start to run lean and introduce possible detonation?

while cruisin the Autobahn at 120+ for 15 minutes!

 

Well Ron, that is something I would have to pay a lot of cash for I won't be attempting any land speed records So I don't need to spend €120/piece for metering flow and volume... And that isn't including setting them up, that is just for a flow chart.

As the injectors are 28 years old and have only seen 78k miles of use, I doubt they are worn. My main goal was simply to find out if they are leaky or blocked and if they need some major servicing.

I'll see tomorrow how they perform on petrol and how the pattern is. Should be a useable one...

And I'll be going 130, tops - kph that is! Irresponsible to go faster in such a beautiful car with all the work I am investing. If I want to go faster, I can still use my XJ8... It'll do about the same vmax with less fuel consumption and more safety

 

Daim, lower pressure will reduce atomisation, as will the higher SG liquid.

I would not use a 12v battery to pulse the injectors without a large resistor in series with the wiring. At 12v the injectors will draw 4amps (48watts) and will get hot. You could use a 4ohm 100watt resistor this will drop current to 1.7amps. Or use a 2x1.5 volt batteries in series this will draw 1amp.

Did you replace the filter baskets before running the cleaning.

 

found an old pic of my injector flow bench, Asnu/Ram, made in Australia, 1995.

anything that you feel OK with go with it, but thats not the best way, you can fudge/B crap most things in car modifing, but you should NEVER BS the engine!

 

I removed the baskets before doing so. The cleaning agent is pure so no possible impurities could get in the injectors. Once the fuel is tried, I'll fit some new filters.

I didn't use the injectors long at a time. Maybe a total of a few seconds. Not really enough time to get hot (in my opinion). I might simply do the 1.5V batteries instead. That seems a little easier to do. I was always under the impression, that a 12V car battery would do as long as you don't over do it with the connection duration...

 

That is the thing Ron, I'm not modifing this car at all. It is staying as original when it comes to it's engine set up as it can be... I could always buy 12 new injectors but I'd be paying more than EUR 1200 for them. Or I can have them charted for the same cash. Or I can clean them and refit for a fraction because they all work...

I have my limits to where I want to go. As I am going easy cruise classic car style, there is no need to meter the flow to be equal and get spot on the same flow rates in all the injectors, especially because not all cylinders draw in the same amount of air due to restrictions in the intake manfold with it's unequal length runners...

If I were going for a racecar setup or like Warrjon a larger displacement motor, I'd be tweaking the hell out of everything here...

 

So, day two of "check the injectors".

I decided to modify my setup like Jigjag suggested. Worked quite well until my spare FPR decided to start peeing fuel out of it. Was an "old" one anyway (probably old enough to be f**ked in the first place!) from my "donor car".

Lacking a T connector, I used a brand new crank case ventilation activation tube That worked well. I still used the battery as a direct connection. Works well. I could use a small battery (or 2x 1.5V) but the car battery works and I couldn't be arsed to go out and buy some batteries

So then, here the set up in video form:


As it was running at 2.5 bar (the pressure regulator used was a 2.5 bar one from the return side of the fuel system), the jet turned into a spray and that looked nice.


ALL injectors worked perfectly and simply spray a great pattern. I even managed to get a burst picture of the spray:



So I am happy, that no drips or blocks are in the injectors. Everything works perfectly. I guess leaving the injectors in the cleaning agent over night didn't do much harm. Might even have cleaned them up even better

 

fair enough, but for what its worth , i would not have even wasted the time!

just put them in and run some good fuel they would probably clean up on there own!

at least good enough for your needs.

 

I wanted to make sure, that they all worked, as I did have some "issues" on idle with a lumpy engine... I assume it is ignition based but I can't say much, as the engine hasn't ran now for a long time

At least I know all injectors work. With my luck, had I just fitted them without checking, they wouldn't work properly... Better to check whilst apart than to check later when it is all assembled

 

That spray pattern look a bit wide and offset, with a void in the middle. The pattern from these injectors should be almost a stream.

 

like warron said, now if you had 6 injectors on the machine , all flowing you could measure the CC amount, and see the patterns one against the other!

you can adjust rpm and pulse width from idle 500rpm + strokes, all the way to 10000rpm + strokes.

you can also adjust fuel pressure, and visually see the pattern may change shape!

OK that said some times odd things can happen , like pushing fuel pressure VERY high!

some injectors can go Static at hi rpm, static is a phenomenom when needle cant close because of hi stroke volume, and press. so needle may lock 1/2 open and 1/2 closed, in middle travel, engine instantly goes super lean, and PUFF the Magic Dragon!

how do i know that, been there done that!

i played with that machine for 15 yrs, if i had a serious money engine i would sure have them cleaned and BALANCED with a spec sheet of results of tests!

sometime its possible that an injector cant be brought into calibration, and test tech finds another that tests out within 3% or closer if possible!

like i said you dont have to do it, it becomes a nerd thing!

some times trying to hard to be perfect, or just put them in and run it with a fuel cleaner, and see what happens, OR you get really out there and start to measure exhaust AF ratio at different load and rpms!

its only an engine , there are many more out there!!!??LOL.

sorry im ranting.

 

The glass does actually make it look weird... Reflection and co.

 

I cleaned mine in a very similar manner. I used acetone. On first try there was a very observable difference in spray pattern. It was obvious which were plugged. After running a 1/2 pint or so through they cleared up and all patterns looked alike. I was happy with that. After all these cars are made for highway use and have to absorb some imperfections. Normal drivers are not going to get there injectors removed and cleaned with out drivability symptoms.
BTW I did the acetone spray runs outdoors and still made sure I had a fire extinguisher handy. Kind of dangerous.

 

Hi Daim

When I cleaned my Injectors they were spraying a much thicker Stream of Fuel than yours, maybe even twice as much as yours.

They all seemed to be about the same and I was happy with that but although I didn't think to make a comment at the time.

Your Spray pattern seemed so fine (Thin) in comparison to mine, where the juice was really gushing out.

 

Technically, a fine spray is what is wanted, as it allows forma better mixture. The larger thendroplets, the worse they will ignite and can cause punktual hotspots... And they canncause burnt pistons.

I have, in the meanwhile, had a Bosch service check the spray pattern. Next to new 'Fast wie neu' as the bloke said...

 

Yes, but that would require different injectors, These ones should spray a thicker stream, indicating they are still not clean reducing the fuel quantity they supply.

You need to modify your test setup (lower voltage) to allow the injectors to open for longer, and spray them for 10-20 seconds at a time.

 

Well, as said, the "Bosch Service" (Bosch Dienst) said that was fine... They only do Bosch things all day...

I'll test one injector with the said 2x 1.5 V battery later on. It isn't mega urgent, as the engine won't run yet for a while