Injector upgrade

[bmw444]

Hi
I have 1 280 150 130 injectors fitted to my car which need reconditioning and am looking to upgrade them. I have an "040" ECU as well (mid 80's 733i engine). For reasons of originality I don't want to upgrade the early Motronic to later 1.3 etc.
The original injectors are low impedance, 2.3 Ohm, 192 cc/min, 18lb.
I am looking for some more efficient spray pattern injectors and know people with later E30's have replaced their injectors with later design ones from an M50/52 engine. However these are all high impedance and may not work for me.
So I have a couple of questions.
Are there any later injectors which are similar spec to mine . ie low impedence , similar flow rate etc?
If not can I use high impedence injectors with my early Motronic type ECU ( which is 24 pin so no easy chip upgrade I believe)?
Thanks

[motormanmick]

Hi, from my understanding of electronics, low impedance injectors will draw more current on 12v than will high impedance injectors, amps/current is voltage divided by resistance/impedance (roughly) so 12v divided by 2.3 Ohm = 5amps abouts for low impedance injectors, for high impedance injectors 12v divided by 12 Ohm = 1amp, its quite a bit less current, so less drain on the system. So in theory, high impedance injectors should go straight on. Best injector for your car is probably Bosch 0-280-155-710, is disc type with 4 small holes instead of 1 for a better spray pattern and same size with same electrical connection type, is 18.25lb, just looks different. hope this is of some help, cheers.

[bmw444]

Thanks for the info morormanmick.
Has anyone here actually used a high impedence injector in place of a low impedence one?
Thanks
Chris

[bmw444]

Anyone tried this?
Thanks

[Brianmoooore]

You won't damage anything by fitting a high impedance injector in place of a low impedance one, but I can't guarantee that the ECU will drive them.

[Mikey_Boy]

Brian is spot on there - the drivers in the ECU will probably struggle. Best just to recondition the items you have??

[motormanmick]

Hi guys, not correct, Ohms is not a measure of power used, the injector driver will be doing less work to drive the higher impedance injector (12 Ohm). This is proved by this calculator http://www.ohmslawcalculator.com/ohms_l ... ulator.php
enter in 12 volts @ volts
2.3 @ resistance
results are current is 5.2 amps or 62 watts of work to drive the injector.
now feed in 12 volts @ volts
12 @ resistance
results are current is 1 amp or 12 watts of work (about 1 fifth of the effort of driving the 2.3 Ohm injector)
It will work. cheers

[Mikey_Boy]

Clearly you know more about this than any of us....

Away you go and good luck!

[motormanmick]

Sorry, not trying to be a pain in the butt, am an electrician for 37 yrs and specialized in electric motor and coil rewinding and injectors are only little coils, just trying to help bmw444, I did look at same option for my 318 m40 but decided to drop in an m50 instead.
Cheers

[Mikey_Boy]

Not doubting your knowledge at all fella - my guess would be that the ECU I would have trouble translating the differing resistances into the right injector pulse width - the maths will always give you the number - the interface between the maths and the code might not agree...

[gromgsxr]

normally low imp injectors are driven 2 common ways, either using external resistors to limit the strain on the injector drivers or by 'peak and hold' using high current to open the injectors and trailing off to low current to keep them open.