BoatBanter.com - View Single Post - I still don't want the stuff in my boat tanks

X ` Man

On 1/3/12 9:21 AM, Happy John wrote:
On Mon, 02 Jan 2012 23:44:55 -0500, wrote:

On Mon, 02 Jan 2012 21:46:40 -0500, JustWait
wrote:

There is a moment in time when you first go to start your engine called
"key on, engine off" when the computer gets it's charge and looks at all
the sensors for their 0 (zero or null) reading. The IAC (idle air
control) for example is a small piston in the side of the intake which
bypasses the throttle body and makes micro adjustments to the air flow
to the intake while the gas pedal is off, and the throttle body is
closed. This is necessary with injected cars to allow for changes in
load from other equipment on the car, etc... The IAC has a capacity for
movement and that distance (the throw of the piston) is segmented into
256 units. When the vehicle enters that KOEO moment, the IAC closes all
the way and the computer notes where it bottomed out in along it's range
of motion of that 256. Let's say the piston bottoms out at positition 7,
the computer uses that setting as "zero" in it's calculations for the
remainder of the engine run... If there is **** and carbon in the IAC
for instance and it can't really zero out, the car will idle ****ty...

The idle control solenoid on a Mercury EFI 60 is just on or off. It
crosses to a Cummins diesel part if you look hard enough. It just
pulses the solenoid at idle.
That is the "paka paka" sound you hear when a Mercury is at idle. The
throttle body seems to be completely closed. I wore two of them out in
3000 hours of running, with a lot of that going slow. (manatees). I
took both of them apart and there was nothing unusual looking in
there, just wear between the plunger and the coil housing. I assume it
cocks and binds. A little squirt of oil made it better for a while but
you really need a new one to make it right. ($50 or so). The first
time it took me a while to figure it out, (pull the hose off and pinch
it down, the motor idles), the second time I just knew what it was,
the paka paka sound wasn't right and I just ordered a new one, changed
it on the lift.

I think my Yamaha works the same way but I have not really looked into
it. If anything I would like to see it idle down a little faster tho

Well, gosh. I don't hear any of those sounds. In fact, I have to ask my wife if the damn Yamaha is
running when I start it. I don't usually wear the hearing aids while boating.

It's not your bad hearing. My hearing is pretty good. I couldn't tell
when my Yamaha 150 was running at idle, either. If I buy another
outboard rig, it'll have a four-stroke Yamaha on it.