Commanded timing doesn't log accurately

[SVT_Z06]

My commanded timing doesn't match my logs. Commanding 19.99 and it shows 19.50. I have the latest version, 3.0.37.

[mowton]

Have you verified that none of the add/subtracts like IAT, ECT, etc. are in play....Also each cell covers at least 100-200 rpms so you may be on one side or the other depending on the g/cyl. And lastly to get the accurate g/cyl that the PCM is using, you need to develop the g/cyl airmass parameter from the Dynamic Airflow parameter......([2320.234]*120/8)/[12].

Ed M

[ElecTech]

And lastly to get the accurate g/cyl that the PCM is using, you need to develop the g/cyl airmass parameter from the Dynamic Airflow parameter......([2320.234]*120/8)/[12].

Ed M

What not use the Cylinder Airmass PID?

[mowton]

What not use the Cylinder Airmass PID?

Because they are based on MAF airflow which isn't always equal to the the exact amount of air actually entering the cylinder. This is especially true during acceleration and deceleration where the manifold is acting as a "spomge or a spring", absorbing some of the reported MAF airflow. At this time, and at some lesser level all the time, the pcm is "filtering" the MAF airflow with VE data, and the Dynamic Airflow is the resultant value. So developing the Cylinder charge from that starting point makes more sense to me as that is what the PCM is doing as well.

Ed M

[SVT_Z06]

spark.PNG

Hi. Thanks sooo much for responding.

I confirmed that no tables are subtracting spark and I think I set up the spark advance properly. I'm also having trouble getting it to show 'Last' instead of average.

[mowton]

Hi. Thanks sooo much for responding.

I confirmed that no tables are subtracting spark and I think I set up the spark advance properly. I'm also having trouble getting it to show 'Last' instead of average.

First off you are only talking about .5 degrees difference and there is rounding and as I said the table only represents the value at that exact RPM and g /cyl. Make sure the RPM and g/cy table values match your tune editor table.

Last Value only works during live scanning in 3.0, just the way it has been implemented.

Ed M

[SVT_Z06]

I'm a bit confused. I created a math parameter with that data, but I'm not sure how to graph it. I put it in my Charter vs. Time section and I'm seeing values like 78.1 to 80.1 at wot. Should this be grams/second?

[mowton]

Because I'm and idiot....I typed it wrong....sorry

([2320.234]*(120/8))/[12.56]

Ed M

[SVT_Z06]

Because I'm and idiot....I typed it wrong....sorry

([2320.234]*(120/8))/[12.56]

Ed M

No worries at all. Thanks. I guess I need a little direction as to what to do with this data and what I can log it against. In the chart vs time, I can see it rise at wot. Also, should it be in grams per second? I changed it to lb/min and other units, and those numbers stay the same (77.2 - 79.17, etc.)

[mowton]

Do you have Dynamic Airflow and RPM in your channel table and using the same in you math parameter?

Ed M

[SVT_Z06]

Yes, they are. What kind of values am I looking for? Units? Will I be logging in a 'Graph' layout? If so, what would be the 'Label', 'Column Axis' and 'Row Axis'?

[mowton]

Yes, they are. What kind of values am I looking for? Units? Will I be logging in a 'Graph' layout? If so, what would be the 'Label', 'Column Axis' and 'Row Axis'?

You wouldn't normally log the values of DCA (g/cyl) in a table. It is used more as an axis parameter to develop tables for say Spark, DFCO etc. Things that are referenced to the grams per cylinder parameter so the Label (DCA) is what you call in your Math Parameter.

Ed M

[drj8787]

While searching for info on knock retard I seen this thread and thought it may have some info to offer me. Could you take a look at this screenshot and this thread of mine on ls1tech? I don't know what hes asking me to do.
http://ls1tech.com/forums/pcm-diagno...ck-retard.html

I made a new graph for knock retard I used cyl air mass as a axis so it matched the editor then I seen this thread and what you said

mowton


Have you verified that none of the add/subtracts like IAT, ECT, etc. are in play....Also each cell covers at least 100-200 rpms so you may be on one side or the other depending on the g/cyl. And lastly to get the accurate g/cyl that the PCM is using, you need to develop the g/cyl airmass parameter from the Dynamic Airflow parameter......([2320.234]*120/8)/[12].

Ed M

and that is where I think it starts applying to me and what I'm trying to do. the table and lay out I'm posting here and not attached with the others I posted in other thread

[SVT_Z06]

([2320.72]) appears to be my Dynamic Airflow parameter available. not [2320.234]. This selects Air Fuel Ratio as the 'Unit' which is strange.

Now you got me curious to get the accurate G/Cyl. I'm guessing the Cylinder Airmass PID isn't accurate? What do I need to do to get accurate G/Cyl? Right now, my formula is this: ([2320.234]*120/8))[12.56] and I tried ([2320.72]*120/8))[12.56] and it doesn't appear to log the correct units. I guess I'm looking for 0.XX values?

[mowton]

([2320.72]) appears to be my Dynamic Airflow parameter available. not [2320.234]. This selects Air Fuel Ratio as the 'Unit' which is strange.

Now you got me curious to get the accurate G/Cyl. I'm guessing the Cylinder Airmass PID isn't accurate? What do I need to do to get accurate G/Cyl? Right now, my formula is this: ([2320.234]*120/8))[12.56] and I tried ([2320.72]*120/8))[12.56] and it doesn't appear to log the correct units. I guess I'm looking for 0.XX values?

Yes another fopar on me..... .72 is lb/hr (i use g/sec or .71) for dynamic air. Not sure what I was thinking when I typed it. Sorry. .234 is 14.7 AFR???????

([2320.71]*(120/8))/[12.56]

as copied from my Math Parameter

Unit will be X.XXX or 0-1.36 at the most.

Ed M

[mowton]

While searching for info on knock retard I seen this thread and thought it may have some info to offer me. Could you take a look at this screenshot and this thread of mine on ls1tech? I don't know what hes asking me to do.
http://ls1tech.com/forums/pcm-diagno...ck-retard.html

I made a new graph for knock retard I used cyl air mass as a axis so it matched the editor then I seen this thread and what you said
and that is where I think it starts applying to me and what I'm trying to do. the table and lay out I'm posting here and not attached with the others I posted in other thread

Jared, I would be glad to help out. First lets think what do we want to do. He is asking you to log the Knock retard levels against the same X/Y axis as the Editor Spark Advance so you can identify the amount of knock and what the PCM was commanding as far as advance. If you look at the Spark and Retard pre-configured Graphs, they are referenced to RPM and MAP....not RPM and G/Cyl as the Editor Spark table is. As I stated, the g/cyl (along with RPM) parameter will point you to where the PCM was accessing the spark advance. Logging the Spark Knock against the same RPM and g/cyl will lead to the spot that the Spark advance may be "adjusted" to reduce the spark knoc......I use the word may because you need to make sure the knock is real and not a function of excessive valve train, mechanical contact or exhaust (headers) noise resulting in false knock. Further to that, I am stating that the g/cyl derived from the Dynamic Airflow is a more accurate rendering of what the PCM is calculating so you are better to use that.

I have posted a screen shot to help in the explanation and I will copy this response as well for you or any others that might be interested.

Let me know if you have any other questions

Ed M

[SVT_Z06]

Thanks, Ed. Appreciate the help.