The ECU has the ability to see the signal from the MAP at different times. It's a feature called Map Sync. The signal is looked at at a very specific point in time near the closing of a valve and also has to be within RPM and throttle thresholds. It's odd to think about because on data monitors we see what looks like a more or less steady reading. There's a lot to it, but it does it.

 

Thanks for the reply. I understand that the ECU picks a specific time to read MAP for fueling and timing as does the ignition units on carbed models for timing but I did not know that they use those values to validate cam/cylinder phase.

 

You're welcome. It's a pretty cool process. Some smart people programming this stuff.

 

Did this enable Harley to eliminate the cam sensor that was on the early model first generation TC?

 

yes - i’ve seen this strategy used in several delphi EFI systems including the Yamaha MX825V EFI used on lawn and garden equipment.

I’ve also seen similar strategies in diesel

 

The cam sensor was eliminated on carbed bikes in 2001 and on Delphi EFI bikes (softails) at the same time. Magneti Marelli baggers still had them in 2001 but were gone when the baggers converted to Delphi in 2002. IIRC

 

Just to attempt to summarize and get all Ed Rumberger's info together is in bold. Directly below is my understanding which may or may not be true.

Obviously, below has to occur when the engine first turns over and does not throw a spark till compression stroke is established.
Then pretty much, the FI bike runs off of a MAP for the amount of fuel it adds and this is determined by TPS (throttle position sensor), MAP (manifold absolute pressure..vacuum) and Intake Temperature Sensor.
Interesting also that the Vehicle Speed Sensor is used as an input for idle speed control.
Obviously, I guess stock MAP is designed to maintain Stoichiometry 14.7-1 fuel to air ratio during a cruise, richer at cold startup or WOT by controlling on time of the fuel injector.
Oxygen sensors modify MAP at a learned fuzzy logic from operator habits and are not
an instant change to MAP reading like the MAP or TPS.


Ed Rumberger's summarized info from the above posts.

The two missing teeth on the 30 teeth flywheel tell the ECM TDC information of the pistons. (ever 12 degrees)
Because it is a 4 stroke cycle, it takes 720 degrees of flywheel rotation to complete.
In that 720 degrees, the piston is at TDC 2x (Compression & Exhaust)
Because there is no cam sensor, the ECM must find phase - it needs to know which one is compression so it can throw a spark.
On compression, the flywheel speed slows (ever so slightly, but the ECM can see it easily)

It also cross-checks with a signal from the MAP sensor and it has phase and can then throw a spark.
The ECU has the ability to see the signal from the MAP at different times. It's a feature called Map Sync.
The signal is looked at at a very specific point in time near the closing of a valve and also has to be within RPM and throttle thresholds.
It's odd to think about because on data monitors we see what looks like a more or less steady reading.

 

This brings up some questions What happens when the MAP does not match the what it should be and the software thinks that the phasing/timing is lost? Does it shut the motor down or simply adjust the phasing and go on? Does it throw a code when the error occurs? Say a valve sticks open?

 

It looks at other values and deltas.

There was a time when people were installing S&S easy start cams in stock compression bikes and they wouldn't fire - that was an issue.
However, with compression it will find sync and run. The caveat being that the read may be off - example installing a cam with a very incorrect map and the thing idles at 50kPa. That is a telltale that the flashed map and the cam profile are way off.

 

Well it’s running again. The problem was a combination of having the plugs out and a bad ground wire where it plugs into the ECM/U. The only one we hadn’t initially checked.
Thank you to everyone that helped me with figuring this out!