Load scale units

[finnigan001]

Hi Guys,

Probably a super obvious and straight forward answer but i have searched everywhere and have not found a confident answer to this.

Are the Load values on the x-axis of the Fuel Base Cold(ECT,Load) and the Borderline Knock(RPM,Load) tables simply percentage as one would expect?  The reason i ask is that the Load on the Fuel table goes up to 1.5 inferring 150% and the BLK goes to 200%.  If it is percentage why does it go so high? Are there circumstances where load can get this high?

Thanks and keep up the great work. Truly the best money I've spent.

[Roland@pcmtec]

Load = airmass / maximum cylinder airmass at atmospheric pressure. 

So in an NA car technically the maximum air mass you can get is when vacuum drops to zero (eg atmospheric air pressure) which would be a load of 1.0

In a turbo charged vehicle you can go above atmospheric air pressure and hence load goes above 1.0

Eg atmospheric air pressure is 101kpa so at a boost pressure of 101kpa (total pressure = 202kpa) you would have a load of 2.0

101kpa is 14.7 psi of boost 

If you run 30psi (206kpa) your load would be 206 + 101 / 101 = 3.0 load etc 

[finnigan001]

Thanks for clearing that up!

So my next question. Do the load readings that’s come out of the obd2 connector (0-100%) relate to the load on the tables?  

 

Just having a bit of trouble pin pointing cells. Slowly getting there. TPS by AD count is another one. I’ve read that 580 counts is WOT. But yeah, matching that to tps% requires bit of extrapolation/ hope that it’s actually 580.

[Darryl@pcmtec]

The load values that come out of the OBD2 are pegged at 100% like you say. The load values that are on the Spark axis etc are calculated as per @Roland@pcmtec post. See if you can log something like Air Load. You really need to log the DMR value Load to get that accurately but other vendors think air load is good enough. Air load is usually something along the lines of MAP reading/Barometric pressure and is reasonably close to load.

Throttle percentage, from what I have seen, comes from AD count /1024 in other products. So WOT in your example would be 580/1024 or about 57%.

 

[Turboidiot]

Would there be any reasons or tips on why load at 14.7 psi of MAP would read higher than 2 like 2.6.   Seems like the map reads correct but load is scaled incorrectly? 

NA PCM converted to 2bar logic with 2 bar map sensor.  

[Roland@pcmtec]

Load is calculated via speed density. So your speed density slope and offset tables will need adjusting to suit the engines new VE. Being an NA motor with higher compression you are going to read more airmass (and hence load) at a given MAP pressure .

Or you have a have the map sensor offset flipped (turbo logic negates the offset for some odd reason).

Do you have a turbo cal or the turbo logic switch enabled?

[BeerTurbo]

On 12/28/2023 at 12:44 PM, Roland@pcmtec said:

Load is calculated via speed density. So your speed density slope and offset tables will need adjusting to suit the engines new VE. Being an NA motor with higher compression you are going to read more airmass (and hence load) at a given MAP pressure .

Or you have a have the map sensor offset flipped (turbo logic negates the offset for some odd reason).

Do you have a turbo cal or the turbo logic switch enabled?

does the predicted load tables do anything for the load calculation, or is that more to estimate TQ produced at a certain load number?

On 12/28/2023 at 12:30 PM, Turboidiot said:

Would there be any reasons or tips on why load at 14.7 psi of MAP would read higher than 2 like 2.6.   Seems like the map reads correct but load is scaled incorrectly? 

NA PCM converted to 2bar logic with 2 bar map sensor.  

recent fg +turbo i was data login was hitting a load of around 1.5 at 10.5psi and i thought that seemed a little low. so looking into possible explanations for that now.