HPDI ECM Peak Voltage

[jrchandler]

I have a ZV200TLRC. I checked the ECM peak voltage output (using a DVA adapter) going to the coils as shown in the manual on page 8-15 and got 16 volts. The manual says it should be 270 v when cranking. The pulser coil tested ok with all readings 3.8 to 4 volts when cranking. Is 270 volts correct? Does this mean my ECM is bad? Seems unlikely but this thing just does not like cold starts.

[Keithbaja]

DVA from ECM 160 min. 260 DVA above 1,500 rpms. Don't test
with ECM disconnected or damage to ECM could occur....

[99yam40]

DVA from ECM 160 min. 260 DVA above 1,500 rpms. Don't test
with ECM disconnected or damage to ECM could occur....

does that mean do not disconnect the wires from ECU to the coils?
Only check circuits loaded?

I am suprized those motors use Capacitance discharge ignition with ECUs, I would have thought they would have used the 12V like cars

[jrchandler]

The positive side of the coil is supplied 12 v from the distribution block. The negative side is switched on/off by the ecm. How is the ecm providing a high voltage spike on the negative side?

[99yam40]

maybe the building and collapsing magnetic field in the coil itself creates voltage spikes that can be read with a peak reading meter.
I have no idea

where does the manual say to hook up the meter leads to?

[jrchandler]

The 2 pin test harness goes inline on the coil power input.

[99yam40]

so that should be across the 12 volt + & - wires from the ECU to the coil ?
you did have the coil also tied in like Keith mentioned, right?

[jrchandler]

I’ve tried it coil hooked up and without the coil. Shows 16 volts using a DVA adapter either way. Which would be right if it’s pulsing straight battery voltage. But the manual says it should be 270.

[99yam40]

Sorry, but I am of no help on if or how it would read that high.
I have found problems with service manuals before,
but if others see that also in other manuals then you would think it would be correct

is this motor not sparking any plugs?

[jrchandler]

I am getting a spark on all plugs. I’m having trouble with cold starts. Ecm peak voltage is in the troubleshooting guide for hard starting.

[99yam40]

getting spark on all plugs means you need to check on extra fuel for cold starts maybe.

a shop might use a KV tester to be sure the plugs are getting the proper voltage

[boscoe99]

does that mean do not disconnect the wires from ECU to the coils?
Only check circuits loaded?

I am suprized those motors use Capacitance discharge ignition with ECUs, I would have thought they would have used the 12V like cars

They use a transistorized ignition system. Like most modern cars do.

[boscoe99]

I am getting a spark on all plugs. I’m having trouble with cold starts. Ecm peak voltage is in the troubleshooting guide for hard starting.

ECM is not tested if there is good spark.

[boscoe99]

[99yam40]

They use a transistorized ignition system. Like most modern cars do.

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?