Hi, I am having a discrepancy between the rev counter in my Optimiser display, and what my Tacho displays.  in order to resolve the discrepancy, I consulted Carl Allison's Sport 1100i schematic, and determined that pin 24 is the Tacho output.
 
1) Is this correct?
2) What frequency should I be seeing for the 10V output wave, and what is the conversion factor (freq/rpm) ?

I suspect that the Tacho is experiencing either a grounding or +12V issue, but I need someplace to start from to determine what I should be seeing.  MyECU switches are set to 1,2,4 off, 3 on.

Thanks for any help.

Yes it is pin 24.
The Optimiser will be the correct reading.
What sort of discrepancy are you seeing?

The optimiser reading is ~500 and the Tacho is reading 1000 at idle.  The Tacho becomes unreliable  after that, showing as much as 9000 with 2500-3000 on the optimiser.  If the optimiser is the accurate reading, then I can check the frequency at pin 24 and do the math myself.  I have a scope so I can check the square wave at the pin and at the input to the Tacho and see if there is a problem in the wiring.

Thanks for the confirmation.

Which Optimiser are we talking about, the Android Optimiser?

Is this a new symptom?

Can you check function with the OEM ECU?

I haven't checked with the Android Optimiser, I have the Optimiser plugged into the MyECU port.  I don't have an OEM ECU, I sent it to you when I bought my MKIV  MyECU, but I have the MKIV, and I can just plug it in to check.  So, here is my plan:
1) I will check to see what the Android Optimiser says.
2) If there is still a discrepancy, I will plug in the MKIV ECU and check.

I will let you know tomorrow how things went.

Well, things went quicker than expected.  Using the Android Optimiser, the RPM readings are virtually identical, so my plugin Optimiser must have a "hitch in its gitalong".  I was hoping to just use Autotune to get the map updated, but it looks like I will have to log a run or two with the Android Optimiser, and edit the map by hand, instead.  Oh, well...

Thanks for the help!

I don't think I've ever connected an Optimiser to a Mk VII.

The MKVII has some changes, including running at twice the speed as the previous versions. This will give you the 2x difference you are seeing as the Optimiser doesn't know of these improvements.

You should only use the latest ECUController ( v168 ) with the MKVII. v168 will work with the older ECU.

The Android Optimiser will do all you need for auto tuning automatically, just after the ride.

OK, now I'm confused.  I just re-read the Android Optimiser manual, and there is no mention of Autotune.  How do I accomplish that? 

Modification:  I re-read page 7, and now I understand.  Android Optimiser makes suggestions after a ride, and I have to accept those suggestions, then save the new map to the ECU, right?  (It's not your English, it's my focusing on the word Autotune rather than just reading and understanding.)

First log a ride. You should see the map populated with numbers that are suggestions. Then go into edit map and select suggestions. This can be done after replaying a log also.

Got it!  Thanks again for all your help!