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I haven't used the washer system yet. If you do it, then you need to atomize the water through a nozzle of some kind so it is not just water in liquid form blasting into the intake.
My truck will knock under a specific range of load, typically at low speeds in higher gears which is the way I like to accelerate in gears. I can just let off the throttle slightly to keep it from knocking to the point where it could damage the engine.
I hardly ever use the washers anyway which makes them the obvious choice as a supply of water. I intend to use some alcohol with the water when it is injected.
Since my truck has just over 126k miles on it now, it's safe to assume there is some carbon accumulated in the combustion chambers. A simple injection setup will allow me to see if there are any results. That being said there are some things that need to be understood. Slight spark knock is a good indication that you are running as much timing advance as you can which is actually OK, but when you get into heavier spark knock you can do real damage to the engine so be careful and avoid introducing a lot of water without any spray pattern into the intake. Also make sure you are injecting the water in such a way that it is evenly distributed between the cylinders and you do NOT inject enough to cause a liquid lock or you can destroy your engine.
My intention is to make a very small orfice in a piece of steel or aluminum and insert it into the hose going to my vacuum fitting so it can not be ingested into the engine.
Most cars have a means of adjusting the timing advance to reduce or eliminate spark knock, by changing the ignition signal or changing the computers signal to the ignition coils. The days of just adjusting the distributor are mostly gone but if you have a distributor then just move it slightly in the direction of rotation to retard the timing.
A good way to check to see if you might be able to stop the knocking is to try higher octane fuel, or a different brand of fuel. That may be the best solution, but the approach needs to be systematic. Good EGR volume is critical to stopping spark knock.
Your plugs should be fairly fresh and I would (and have) used some fuel system cleaner. One of the best is BG 44k which has been recommended by Mercedes for a long time, but I have reservations about believing that any cleaner can really remove all carbon deposits from an engine.
Even a weak oxygen sensor can cause spark knock and sometimes it takes several different things to get it resolved. Maybe just be patient and see how mine goes before jumping into it with consequences that I would not like to thing I was responsible for causing with my recommendations. Mass quantities of water injected in the wrong place could cause problems with the various sensors involved in air flow measurement so it is best to introduce water downstream of those same sensors.
Mom has a phrase that says "yard by yard, life is hard, inch by inch it's a cinch". Basically start with a little and gradually increase the volume instead of starting with a flood and wrecking your engine or other parts.
regards
Mech
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