Fuel Injector Cleaner

If you happen to own a shitty BMW with dirty fuel injectors, here is my proven low cost solution.

There are two parts to be sourced, an ultrasonic cleaner and a 5 pin automotive relay with pin 87a (the NC contact). Wire as per diagram below (or any way you wish) 



The ultrasonic cleaner can be bought from lots of eBay stores. A small one (750mL) will cost around $45, this being about half the price of a single injector.
Here is a link to one such item
https://www.ebay.com.au/itm/Stainless-Steel-Industry-Digital-Ultrasonic-Cleaner-Heated-Cleaning-Tank-Machine/153018030767?hash=item23a095daafmQs0PeWemkoLj07vSqTpdfg&var=452828480841

I used kerosene in the ultrasonic bath but there are many other chemical choices, diesel, degreaser, carby cleaner etc. Probably best to not use highly inflammable liquid (petrol)

Before attempting an injector clean check its coil resistance which should be around 15 ohms - 20 ohms.
I did each injector separately and they all came good in about 1/2 hour although one took 2 hours.
As they come clean you will see a plume of gunk slowly leaving the injector much the same as an oil spill from a large ship at sea but not quite as dramatic.

If you purchase a larger cleaning unit you can immerse whole carburettors for cleaning. I found that the staining from petrol does not come off but that jets clean up nicely.

The injectors on the K100 are rubber mounted (O ring ?) between the cylinder head and the fuel rail. Probably not a bad idea to replace these 30 year old items during re -assembly

While not in use as an injector cleaner you can use it to clean your false teeth (or maybe at the same time if you are a bogan)  

Note: If cleaning your false teeth you probably should use an alternative cleaning solution, not kero, degreaser etc.