It has been 3 years since going WI with the AEM kit.
Only 1 year since adding a secondary nozzle to spray into the turbo.

Today I was checking the nozzles and was surprised by what I found.
The AEM nozzle was clean. The nozzle is SS where as the plunger is brass.

The M3 nozzle and plunger are all SS and use an external one way valve.
The inside of the nozzle and the plunger had a little layer like painted on rust stuff.
This is with distilled water.

I discovered this while recalibrating my flow rate in preparation to increase boost.
Total flow rate was lower than before.

CLR cleaned them up. Now back to calibration again.

 

Yep. I've seen this too.

Many grades of SS will form a slight rust coating or surface rust when exposed to water--this is probably not widely known. Ironically, the nozzles that exhibit this behavior are designed to be used with much harsher process chemicals (and not plain water).

 

Good to know. Never bothered to check mine after 2.5 years, I guess it's time. Any special way of using the CLR to clean things up? Just submerse the nozzle? Anyone have suggestions on how often to check/change the filter?

 

CLR or vinegar.
I used a cotton swab to clean inside the nozzle after removing the filter and plunger.
Then the same on the plunger along with a very pointed wood toothpick to clean the plunger grooves. Depends on your nozzle type.

I read that an ultrasonic cleaner works great.