HPDI ECM Peak Voltage

[Keithbaja]

The specs I gave you are correct. Outboard ignition system are nothing like a car motor.. The coils don't get 12vdc !! They get a hell of a lot mor e to make a better spark. Were burning oil & gas. Ain't gonna happen with a car spark. Boat mechanics can work on cars.. Car mechs should not touch a boat. I've seen that problem for many,many years. Hear it all the time that inboard or I/O is just like my truck motor. So I can work on it.... NOT !!

[99yam40]

well Keith if this is true, maybe you can explain what generates the higher voltage that the ECU sends to the ignition coils on these HPDI motors

[boscoe99]

OK, but why would the service manual give peak voltage readings to the ignition coils so high for cranking and 1500?
is the service manual wrong?

That would be my guess.

[boscoe99]

The specs I gave you are correct. Outboard ignition system are nothing like a car motor.. The coils don't get 12vdc !! They get a hell of a lot mor e to make a better spark. Were burning oil & gas. Ain't gonna happen with a car spark. Boat mechanics can work on cars.. Car mechs should not touch a boat. I've seen that problem for many,many years. Hear it all the time that inboard or I/O is just like my truck motor. So I can work on it.... NOT !!

In all Yam two strokes except for the HPDI models you would be correct.

[99yam40]

this makes me think the ECU pulses the ground several times instead of just closing the circuit to ground/negative giving a longer spark duration.

Boscoe can you look in some manuals to see what the voltage tests calls for on these HPDI motors to compare to his manual?

Just a thought, but maybe he has the wrong service manual or maybe it covers more models that the HPDI also
Maybe the OP will tell what manual he is using

[boscoe99]

this makes me think the ECU pulses the ground several times instead of just closing the circuit to ground/negative giving a longer spark duration. I read it that the ECU simply removes the ground. Tells a transistor to open. Similar to points opening. At which time the coil does its magic.

Boscoe can you look in some manuals to see what the voltage tests calls for on these HPDI motors to compare to his manual? I looked at the manual for the OP's motor and several others. They have the same garbage. Or it is me not understanding.

Just a thought, but maybe he has the wrong service manual or maybe it covers more models that the HPDI also
Maybe the OP will tell what manual he is using

If the OP has spark, then I think he should be looking for a fuel issue.

[jrchandler]

Thanks for the help everyone. I’m using manual 68F-28197-1F-11 which says it is for a VZ200C. I’ll move my focus to the fuel system.

[99yam40]

If the OP has spark, then I think he should be looking for a fuel issue.

agree,

as far as the statement of " longer duration of discharge" goes I was thinking the discharge of a cap into a coil would be a longer duration than the collapsing magnetic field of the coil when you turned off the 12 volts to the coil, since the cap discharge had to build up the magnetic field and then collapse also
so maybe it pulsed the transistor off and on to extend the spark for a millisecond or 2
just a thought that was floating around in my head

[boscoe99]

CDI THEORY
The CDI system can instantly discharge a high voltage charge to the primary side of the ignition coil. Electron flow from the
capacitor is at the speed of light. The advantage of this speed is that there is little time for the ignition coil secondary lead to
bleed off any of this voltage-to-ground. Because of this high voltage and fast discharge rate, there is less tendency for the
spark plug to foul. The system is even able to jump the spark gap on spark plugs that are partially fouled.

Transistor Con*****ed Ignition (TCI)
A full-transistor ignition system has a longer discharge duration used to burn the fuel in an extremely short period. This system
is not as quick in building up a secondary voltage as a CDI system, however, the discharge duration is 5 to 10 times
longer, with excellent starting and igniting ability.
TCI systems differ from CDI systems in several respects. For one, a CDI system generates its own source voltage; a TCI
system does not; therefore, it must rely on the engine battery voltage. Current flow from the battery is first directed
through the primary winding of the ignition coil; then, to the TCI unit (inside the ECU), then to ground. This current flow
causes a magnetic field to build in the ignition coil primary.
Projections on the flywheel pass the pulser coil (crank position sensor) generating a signal to the ECU. The ECU uses this signal
to determine ignition and injector timing. The signal from the pulser coil will cause the ECU to turn off the transistor and open
the primary circuit to the ignition coil. The opening of the circuit causes the magnetic field in the coil to collapse resulting in a
momentary build-up of voltage in the primary windings.Through mutual induction, a voltage is created in the secondary windings
of the coil (approximately 25,000 to 40,000 volts). This higher voltage is used to fire the spark plug.

[Keithbaja]

Thank you Bosco, I just wrote what the CDI Bible read. Never have worked on a HPDI ignition system yet. Only w/p and filters (lots of filters) only a few around Monterey bay ca. Just don't sea them here. Mercury used that system in the 70's and 80's. Can u share your source of info ?? You are a asset here.

[99yam40]

bad info in service manuals and then people telling him the same thing makes for a difficult troubleshooting process.
but as Boscoe mentioned if it has good spark, no need to chase that rabbit.

OP just realize that the ECU needs good info for it to send out the proper signals to cold start properly.
verifying the rail pressure is in spec like the ECU thinks it is would be good along with the things that tell it the motor is cold starting

[Keithbaja]

I agree if he has spark he should check for fuel pressure. And those motors have a boat load of filters. I think it wins the most filter award.

[jrchandler]

When checking the injector drivers, all were in the 80 v range except cylinders 3 and 5 which were both in the 30s. Still investigating.

[jrchandler]

I switched the injector drivers and the injectors with voltage in the 30s moved to cylinders 2 and 6. I’m thinking I have a bad injector driver. Anything else it could be?