Hondata

I see the si is set to 1700 startup rpm with a taper down to idle of course. My question is could it be possible the car is running too much advance during the stratified lean injection (or whatever fancyness these ecu's do) causing a slight intermittent knocking noise?

Im trying to figure out on my 2018 civic si if it has piston slap/direct injection pump/emissions something/noise during the warm up cycle. Always has since 7 miles and now has 10k. Very minor but a heavy enough sound that I can pick out that makes me concerned.

My thought was to reduce rpm to 1100 at startup during all temps and see if its gone. Im more concerned about engine longevity as opposed to catalytic converter life.

Just looking for some professional information.

It literally almost sounds like the direct injection cam lobe is bouncing the pump actuator intermittently while engine is cold...or a very minor piston slap (although piston slap is usually very consistant)

Imagine a little guy under the plastic valve cover reaching up with a rubber mallet and hitting the underside of the valve cover randomly / sporadically.

They use split injection but it varies with load etc. I don't think it is the problem as it would be hard to get spark knock at that rpm and load.

The engines are noisy - mainly the injectors and fuel pump. You could compare to another vehicle to see if it is more than normal.

Check the knock count and see if it goes up at the same time.

Thank you for the quick feedback!....no knock count issues at all (there for a while I wondered if I would ever see counts increase or knock control for that matter) Your supplied maps are great.

I will try and find a vehicle to compare it to.

In the meantime can you give me your opinion on setting the startup cycle to not exceed 1100-1200 in cold weather (only down to 0 Fahrenheit possibility)

Im assuming the initial flare to 1700 is to get fuel moving and heat the converter for emissions.

Would I have less oil flow overall by limiting to 1100-1200 instead?

Again my only concern is engine protection (your response will not be held against you- just looking for your honest opinion)

If I can get away with this I will set up my next flash that way and forget about the noise for now. This would drastically make me a happier owner.

Here is a solid question only you may know the answer to.

Are either of the cams in a phase that is close to the max degree available ie: could the actuator be lightly bumping this mechanical stop?

Not like a failed actuator rattle but just on the edge of "bouncing" against the stop?

It is extremely random in its severity and consistancy. comes and goes as it pleases. But ALWAYS happens during first start when engine is in warm up cycle. almost like it builds pressure and "pops". Or as if the flywheel is bouncing off its mechanical stop intermittently.

Its odd. Thank you for the help.

Its quite enough a video wont pick it up over the other noises (like injectors) otherwise I would post one.