Logic Spark Outputs /FET Driver MS2 V3

[Breastfed]

Gents,
This is all just a bench test setup at the moment to iron out the bugs.

I'm using the Bosch "211" Ign driver with 4 COP's (2 wire) and I've built the circuit using the TC4427 as per the instructions on P72/188 (HW Guide 2014-08-30)
Spark output is set to "Going High" (same as it was before with the JB Perf 4Ch Driver using the BIP373 setup)

With the new mod's up and running OK I have an issue that needs a simple explanation that I fail to see at this moment.
The HW manual mentions .... "Coils do not receive a spurious signal pulse at power on"
NOTE: the old setup with the BIP373 does not produce a spark at power on.

Findings...
With the Scope or LED I can confirm that there is a signal at power on from both the Ignition logic output (TC4427) and also the Additional Inj drivers (JBPerf 4Ch INJ Driver)
The Scope also confirms the signal on the respective INJ & IGN signals from the 9S12C.

As is recommended the FP relay is also supplying power to the INJ and IGN circuits. As we know the FP is activated for a few seconds.
so here is my thoughts is it possible to add a slight delay of say 100 or 200 ms before the FP relay is activated would this not give the processor time to settle and avoid the Spurious signal, the idea of fuel (or is this the priming Pulse ?) and spark at power on makes me cautious with a supercharged engine or should I not be concerned ?

Breastfed

[dontz125]

The FP relay is activated by the MS, but not until it's ready to control everything. If the coils are powered by the FP relay, there is no chance of a spurious spark.

[ol boy]

This gets back to the old issues with wiring your ignition system on the same power rail as the MS unit. Spark output D (waste spark LS2 coils) would be in the wrong state long enough to dwell the coil trigger line and cause a little cough if there was enough air/fuel vapor floating around in the cylinder. As long as the ignition power line is feed from the FP relay you won't have any uncontrolled ignition events during power on.

[Breastfed]

Thanks for the replies,
I'll check this out with the scope a little closer, however from reading a few Posts regarding this the TC4427 (IGN) should not output any spurious signal but that's not the case ...what am I missing here

Breastfed

[racingmini_mtl]

You may get a very brief output pulse at power on from the TC4427 as that will be driven by the CPU pin which also has the very brief pulse. But if you power the coils from the FP relay as per the manual, that will not be an issue because that pulse will be before the FP output is activated by the code.

One of the first things done in the code is to set the CPU outputs to the correct value so that there is no unwanted side effect at power on. Then later on, the FP output is activated. So you will not get an unwanted spark or injector pulse but you still need to follow the wiring requirements.

Jean

[Breastfed]

Hi Jean
thanks for the reply, your info clears this up.

Breastfed