{B4902} Charge Temperature Filter

[NAH]

Hi,

If I am running MAFless, is this table redundant or does it still hae an effect?

Ta.

[joecar]

NAH,

I believe B4902 is still being used when MAF-less.

Joe

[NAH]

OK, thanks.

I did some logging with DYNCYLAIR_DMA (both the normal one & the Speed Density one) & the value didn't exceed 1.0 grams/cylinder, even at manifold pressure of 125kPa. Does this sound right?

[redhardsupra]

airmass= gmve*MAP/Temp (gmve is the wacky units they store internally, you can make EFILive display your VE in these directly if you want, Temp is a blend between IAT and ECT, in K)

with your MAP being >101kPa i'm assuming this is FI, so at this point you might have a problem with temperatures killing your airmass numbers, that's why intercooling is absolutely crucial.

[SSpdDmon]

I have a spreadsheet I made a while back that I'll upload tonight. It's great for showing VE calculated airmass for two different conditions (ie cool/perfect day* and hot summer day**). The effect the Charge Temp Blending Factor has is quite strong. We can set it anywhere from 0 to 2 in my OS (used a stock 01 M6 F-body file). Depending on what the factor is and using the conditions mentioned above, you can see a 4.7%~10.5% difference in airmass calculations. The more stable 4.7% comes from when the CTB Factor is set to 1, which basicaly equals the engine coolant temp. The down side is, the calculated airmass is considerably less with a higher charge temp. So, do IAT favored CTB Factors work better because they calculate a higher airmass number...even though they have the higher swing in output (10.5%)???

It'll be easier to understand what I'm getting at once I post the SS. I'll try to remember to do so tonight.

*cool/perfect day = IAT of 56* and ECT of 187*
**hot summer day = IAT of 110* and ECT of 217*

[SSpdDmon]

I have a spreadsheet I made a while back that I'll upload tonight. It's great for showing VE calculated airmass for two different conditions (ie cool/perfect day* and hot summer day**). The effect the Charge Temp Blending Factor has is quite strong. We can set it anywhere from 0 to 2 in my OS (used a stock 01 M6 F-body file). Depending on what the factor is and using the conditions mentioned above, you can see a 4.7%~10.5% difference in airmass calculations. The more stable 4.7% comes from when the CTB Factor is set to 1, which basicaly equals the engine coolant temp. The down side is, the calculated airmass is considerably less with a higher charge temp. So, do IAT favored CTB Factors work better because they calculate a higher airmass number...even though they have the higher swing in output (10.5%)???

It'll be easier to understand what I'm getting at once I post the SS. I'll try to remember to do so tonight.

*cool/perfect day = IAT of 56* and ECT of 187*
**hot summer day = IAT of 110* and ECT of 218*
Download VE_Calc_Airmass.xls (http://putstuff.putfile.com/41586/9822588)

[NAH]

Download VE_Calc_Airmass.xls (http://putstuff.putfile.com/41586/9822588)

Cheers mate, I'm having a look now. On a different tack, I noticed from the log file recorded last night that knock was hitting 2.8 & 3.9 on 2 occasions. Need to check the tune for that too.

OK, having had a look at the spreadsheet, from where does the figure 2.436523 in cell B4 derrive?

B4901 & B4902 shows the units for the y-axis as grams/second (B4902 also references GM.DYNCLYAIR_DMA), but MAF is referenced as grams/cylinder in B0104.

What sort of airflow could I expect for a supercharged intercooled setup running approx 5psi? What PIDs should I use to log this (if possible), bearing in mind I have a MAF-less setup?

As you pointed out, it is interesting from your table is that for a hot day, the difference in est charge temp is only 4° higher with the CT @ 2 as oppose to 30° without the factor, which would be right because the major influence is IAT & not ECT (which should remain fairly constant).

So, er what does this mean then? Your point about IAT biased factors sounds logical, I guess the only way to explore would be empirical data collection (unless there are any enginering grads reading this).

[SSpdDmon]

I was hoping someone could use that to help us understand the PCM's calculations better. I'm a fairly smart individual, but this seems to be a little above me.

The VE value comes straight from the tune. In order to see your VE in the default units, you need to click Edit>Properties and use the drop down menu to select the defualt VE units.

(See http://forum.efilive.com/showthread.php?t=3396&page=2&highlight=grams)

As for the Charge Temp Factor Table, I says grams/second and calls out a pid that is grams/cyl. The MAF flows grams/second and the numbers in the table are for 0-150. I highly doubt that table is supposed to reference grams/cyl. Those sound like grams/second numbers to me.

[redhardsupra]

you want to log GM.VETABLE_DMA, MAP, RPM, GM.DYNAIRTEP_DMA, the rest you can calculate from these

[NAH]

Thanks for the tips gents. I'll add the GM.VETABLE_DMA & GM.DYNAIRTEP_DMA PIDs tonight & do some logging.

One question though. B5913 refs the y-axis as grams/clinder. B4901 refs the x-axis as grams/second. Both ref the same PIDs. Is this right?

[redhardsupra]

yup, cylinder airmass is cylinder airmass, no matter where it is

[NAH]

yup, cylinder airmass is cylinder airmass, no matter where it is

But surely one is a mass & the other a mass flow rate?

[SSpdDmon]

Thanks for the tips gents. I'll add the GM.VETABLE_DMA & GM.DYNAIRTEP_DMA PIDs tonight & do some logging.

One question though. B5913 refs the y-axis as grams/clinder. B4901 refs the x-axis as grams/second. Both ref the same PIDs. Is this right?

That was something that was supposed to be fixed the last time I asked. I'll PM your post to Blacky and see what he remembers. But, B4901 refers to the GM.DYNCYLAIR_DMA pid, which reports out in grams/cylinder. However, the y-axis is scaled based on grams/second of airflow as if it were supposed to be using the GM.DYNAIR or SAE.MAF pid. So, logging will always show the first cell being looked up given the fact that I have yet to see cars runnig 5 grams/cylinder. N/A it's more like 0.88 grams/cylinder.

[NAH]

That was something that was supposed to be fixed the last time I asked. I'll PM your post to Blacky and see what he remembers. But, B4901 refers to the GM.DYNCYLAIR_DMA pid, which reports out in grams/cylinder. However, the y-axis is scaled based on grams/second of airflow as if it were supposed to be using the GM.DYNAIR or SAE.MAF pid. So, logging will always show the first cell being looked up given the fact that I have yet to see cars runnig 5 grams/cylinder. N/A it's more like 0.88 grams/cylinder.

Cheers matey :)

[redhardsupra]

But surely one is a mass & the other a mass flow rate?
ok, i took a shot in a dark and apparently i missed :(
if the labels are messed up, you can't help it. that's why i more often look at units than labels. if it's like 5-500g/sec that's airflow, if it's 0.15-1.4g/cyl that's airmass.

[NAH]

That was something that was supposed to be fixed the last time I asked. I'll PM your post to Blacky and see what he remembers. But, B4901 refers to the GM.DYNCYLAIR_DMA pid, which reports out in grams/cylinder. However, the y-axis is scaled based on grams/second of airflow as if it were supposed to be using the GM.DYNAIR or SAE.MAF pid. So, logging will always show the first cell being looked up given the fact that I have yet to see cars runnig 5 grams/cylinder. N/A it's more like 0.88 grams/cylinder.

OK, I have logged GM.VETABLE_DMA. Something wierd (possibly a coincidence as I modified the tune file & uploaded to the PCM prior to logging), but for the first time, I have recorded values above 5 psi (137kPa) at around 145kPa.

Anyhow in reference to your spreadsheet, the recorded data for 5864rpm/145kPa is:

IAT = 18ºC
ECT = 90°C
Air Mass = 1.77grams/cylinnder (GM.DYNCYLAIR_DMA)
VE Table Lookup = 3.45371 g*K/kPa

The g*K/kPa value from the boost table (6000rpm/145kPa) = 3.87. Presumably the difference between 3.78 & 3.45371 is the proportional to the difference in the rpm value.

So putting these figures into the spreadsheet, the values for a 0 factor are 291.15°K & 1.72 grams/clyinder. Do I then compare 1.72 against 1.77?

What does this mean for tables B4901 & B4902? SHould I be setting the factors nearer to IAT?

Phew.

Edit: Is is at all possible to ever get past 10 grams/second on B4901?

[SSpdDmon]

That spreadsheet was developed to merely visualize the effect that table had on the Charge Temp Factor. I don't have the first clue on the right way to set the values in there. As you reduce the factor, the swing in charge temps increases. Likewise, if you reduce the factor, the swing isn't as great...but then again, the airflow numbers look awefully low.

With that table referencing grams/cylinder, you'd need to be running a great deal of boost in order to get out of the first cell. That's why I think either the pid referenced is wrong OR the scale on the side of the table is wrong. As of my latest version of 7.3.2, it still hasn't been fixed. Hopefully, 7.3.3 has the fix. But, I'm not 100% on that one (yet).

[NAH]

Nope, I'm using 7.3.3. Does sound like the scale is suspect.

[joecar]

The PID in B4901 is incorrect.

[redhardsupra]

NAH, could you post your log? i might be able to help you

[Blacky]

Until we fix it in the next release...

You can change it yourselves by editing the file:
\Program Files\EFILive\V7\Configuration\cal_link.txt

Change:
;Charge Temperature Blending
B4901.ROW=GM.DYNCYLAIR_DMA,GM.CYLAIR_DMA,GM.DYNCYL AIR,CALC.CYLAIR

To:
;Charge Temperature Blending
B4901.ROW=SAE.MAF,GM.DYNAIR

Note: You can specify multiple PIDs for linking. EFILive will use the first PID in the list is valid and selected in the Scan Tool.

Regards
Paul

[NAH]

Until we fix it in the next release...

You can change it yourselves by editing the file:
\Program Files\EFILive\V7\Configuration\cal_link.txt

Change:
;Charge Temperature Blending
B4901.ROW=GM.DYNCYLAIR_DMA,GM.CYLAIR_DMA,GM.DYNCYL AIR,CALC.CYLAIR

To:
;Charge Temperature Blending
B4901.ROW=SAE.MAF,GM.DYNAIR

Note: You can specify multiple PIDs for linking. EFILive will use the first PID in the list is valid and selected in the Scan Tool.

Regards
Paul

Cool.

What about the scale (0 - 150). Should this be changed to perhaps 0 - 30?

Also, could the x-axis of the spark octane table be changed from grams/cylinder to MAP in the same way? (Sorry if this is a dumb question).

[SSpdDmon]

Until we fix it in the next release...

You can change it yourselves by editing the file:
\Program Files\EFILive\V7\Configuration\cal_link.txt

Change:
;Charge Temperature Blending
B4901.ROW=GM.DYNCYLAIR_DMA,GM.CYLAIR_DMA,GM.DYNCYL AIR,CALC.CYLAIR

To:
;Charge Temperature Blending
B4901.ROW=SAE.MAF,GM.DYNAIR

Note: You can specify multiple PIDs for linking. EFILive will use the first PID in the list is valid and selected in the Scan Tool.

Regards
Paul
Cool....thanks Paul!

[Blacky]

Cool.

What about the scale (0 - 150). Should this be changed to perhaps 0 - 30?

Also, could the x-axis of the spark octane table be changed from grams/cylinder to MAP in the same way? (Sorry if this is a dumb question).

No, neither of those can be changed.

Actually in the LS2 ECM the axis scale can be changed (not the units though) but we don't offer that option. We may offer axis scale changing in a future release

Regards
Paul

[SSpdDmon]

Per request, here's the new version created to show VE table and COS boost ref'd VE table in grams/cylinder with adjustable IAT/ECT/Charge Temp Factor.

Download VE_Calc_Airmass_2.xls (http://putstuff.putfile.com/45682/3232339)

The default values entered are for an '01 f-body file. Make sure VE values are in default units (click Edit>Properties to change). Also, enter temps in *F and look up the appropriate charge temp blending factor (based on grams/second of airflow). If you need to translate *C to *F, there's a conversion calculator at the bottom of the 'Volumetric Efficiency' tab/worksheet.

[NAH]

Cheers for that.