AFAIK the ECU reports 24* before Xede intercepts signal, subtracts 5.2* (-5.2 value) in the 45-50% load cell @ 7.5krpm and send the signal to fire ignition. 24-5.2= 18.8*

 

The pocketlogger should be showing what the ECU sees for timing, which would be after whatever the Xede is telling it to do.

 

Which is it? Can someone please shed some light on these two (conflicting) statements?

 

My statement is what I remember Shiv said but my memory could be wrong. From what I understand the XEDE intercepts the signal going to the engine and the ECU never sees what the XEDE is doing. AFIK OBD2 reports timing as sent by the ECU map not timing it sees.

 

yea I would think pocketlogger results would be exactly what your timing is, after the Xede has it's way with it.

 

That is the way I see it. The Xede intercepts the signals from the sensors, modifies them and sends them to the ECU. The OBD2 port reads the results that are coming from the ECU back to the engine. If that is NOT the way it is done, then the readings from the OBD2 port with an Xede installed become meaningless.

If there is some other calculation we need to do to get the "real" timing, then I need to know it before I continue to tune my timing from readings of the pocket logger.

 

So you are saying that my timing is not 24* as read by the OBD2 port, but rather 18.8*. Why are you using the 45-50% load cell only? Is that just an example?

 

If what Jorge T is saying is correct, then we should not see changes in the reading of the timing from the OBD2 port when we make changes in the Xede, but my logs show that there are changes. Here are three of them:

Stock timing



Shiv map 93 octane map with 93 timing with 4% fuel added



Shiv 93 octane map with 91 octane timing and 3% fuel added

 

The xede ulters the "known possition" of the crank. This happens BEFORE the signal enters the ecu, not after.

 

So please tell us if reading the timing from the OBD2 port is the "correct" timing? Or do we have to log the timing differently to get the correct timing?

 

You can test this by subtracting some timing and watching your logs to see if they change at the OBD2 port.

 

So I take it that what is stated above is correct...right?

 

Yes. Honestly I don't know where people get some of these ideas. What the hell would be the purpose of datalogging if the datalogger always showed constant timing?

 

LOL!!!

 

I said I may of remembered what Shiv said wrong... also with the XEDE you can take out not enough timing and end up with less overall timing due to ECU pulling timing from knock counts. So yes OBD2 logging will detect changes.