Board logo

zetec injector voltage
mrwibble - 14/12/11 at 10:23 PM

Hi,

i'm planning to refurb my bosch 0280 155 820 beige injectors, i was planning to not only bath them in carb cleaner over night, but try and cycle them with a pipe full of cleaner gravity feeding the injectors.

not being big on electronics, im not sure whether i'll need to add a resistor in line, these are 14.5 ohm high impedance if my research is correct. also i assume they must be 12v as they're driven from a dc car battery, can i do any harm with a 9v battery? just easier to attach croc clips.

oh, and what happens if i get the polarity the wrong way?

thanks for any replies.

Ed

[Edited on 14/12/11 by mrwibble]

SeaBass - 14/12/11 at 10:48 PM

DO NOT energise them for long... A few quick blasts with a momentary switch or they may be damaged. 12v is fine.

I presume your changing the orings, pintle caps and filter baskets.

[Edited on 14/12/11 by SeaBass]

MikeRJ - 15/12/11 at 09:30 AM

A PP3 type 9v battery won't power an injector for very long, if at all, as it simply isn't capable of sourcing the amount of current required. A stack of AA's would be ok. No resistor is required in this case.

You can power a high impedance injector for quite a while (say 10 seconds or so) without damage provided there is some fluid flowing through it, especially at 9v where the power dissipation is well under half the normal amount (obviously they can be powered indefinitely with a continuous flow of petrol through them)

If the cleaning fluid is flammable, remember you will get a spark when you connect and disconnect the injector.

mrwibble - 15/12/11 at 09:33 AM

thanks guys, was planning on a trip to maplins for a little rocker switch to reduce the need for flailing around too much.

SeaBass - 15/12/11 at 09:40 AM

quote:
Originally posted by MikeRJ
(obviously they can be powered indefinitely with a continuous flow of petrol through them)


Sorry Mike - that's absolute cack... They are never on constantly when in use. They have a defined maximum duty cycle.

"Tuners" exceeding the duty cycle can and do damage injectors causing a lean out and expensive damage.

mark chandler - 15/12/11 at 02:12 PM

I triggered mine for cleaning with a 240v to 12v step down transformer and one diode, this is what you get with cheap battery chargers.

It then cycles the injector for ~40% of the time at providing the equivilent at 50hz so equivilent of 1500rpm.

I then used an injection fuel pump directly on the back of the injector to force fuel through (same power source so not running at full pressure), suspended the injector to be cleaned in the top of a big jar, 1/2 filled with paint thinners and sucked the cleaning fluid from the bottom via an old filter.

After a couple of minutes the patterns improved so I swapped out.

Incase the thinners were a bit strong I then replaced with petrol and repeated.

Regards Mark

mrwibble - 16/12/11 at 10:35 AM

so the gravity fed model was a bit of a flop. with 8 AAs driving a push button switch, i got a distinct click every time i fired it but not more than a dribble from the 2 injectors i tried, I guess there was just no where near enough pressure.

anyone know the formula for pressure of a fluid in a cylinder - if i had a tall enough pipe perhaps i'd get a better result?

otherwise i'll need to find a fuel pump from somewhere.

Ed.

MikeRJ - 16/12/11 at 12:46 PM

quote:
Originally posted by SeaBass
quote:
Originally posted by MikeRJ
(obviously they can be powered indefinitely with a continuous flow of petrol through them)


Sorry Mike - that's absolute cack... They are never on constantly when in use. They have a defined maximum duty cycle.

"Tuners" exceeding the duty cycle can and do damage injectors causing a lean out and expensive damage.


Sorry but that is utter cack, you clearly misunderstand the cause and effect of engine damage caused by high duty cycles.

Typically a system should be designed to use no more than about 80% duty cycle, but this can easily be exceeded, especially if you start winding the boost up on turbocharged cars. However, once you reach 100% you no longer have any control over the fuelling, any further demand from the engine can not be met so you get a lean condition. The leaning out is what causes the engine damage, the injectors themselves will be fine.

You absolutely will not hurt a high impedance injector running at 100% duty as long as there is sufficient fuel flowing through it. A low impedance injector definitely will be damaged if you apply a constant 12v, irrespective of fuel flow.

Nick Jones - 17/12/11 at 04:28 PM

High impedance injectors are in the range 12 - 16 ohms. At 12.6 v (typical batt voltage) and 12 ohms you get 1.05A / 13W drawn, which should be no problem at all. Different story with low impedance type though.

Regarding cleaning, see:
http://www.youtube.com/watch?v=VFJlTfHyrUk

There are many other like this - just google DIY injector cleaning.

Cheers

Nick

pjay - 18/12/11 at 08:15 AM

Another method that might be worth considering:

http://www.audi-sport.net/vb/a3-s3-forum-8l-chassis/119767-*-diy-injector-cleaning-how-*-pic-heavy.html

I've only cleaned one set of injectors using so far using this method and just fitted them so early days but engine runs nicely.