Could any body help me to understand Open loop commanded tabels B0141-B0148

[wesam]

I tried to calculate the commanded fuel in E38 in open loop
i tried to use the formula : B0143 + (B0144 - B0143 x B0145) x B0146 x B0148 = Final Commanded Fuel Ratio
but it does not give the same commanded AFR as in the scanner
Also how could the intake valve temperature measured ? I think it should go for temperature higher than the highest temp in the table which is 216 C*

Thanks in advance

[swingtan]

B0143 and B0144 are completely separate, they are used with B0145 which "blends between the two" for the base fueling value.

To put it "crudely, B0143 is like the High octane spark table, B0144 is the low table and B0145 is the octane scalar. So the initial fueling is the blended value of the normal and ethanol tables, if no ethanol is used, then the initial fueling is just B0143.

Final fueling is then B0143*B0146*B0147*B0148

IVT is calculated from IAT, ECT, air flow, spark and fueling. It's a guestimation and not measured but needs to be taken into account for many tables. I'm not sure what you mean by "going for a temp higher than 216C". Normally I'd expect the readings to be between 130C and 150C, over that and something is messing up the calculated temps.

Simon.

[wesam]

I mean that if we used infrared gone on the headers it will show more than 216C so i'm expecting the intake valve which in side the heads will have more temperature than the headers

what will be the down side if i put 14.63 in all cells of B0143 then 1 as multiplier in all B0146,B0147,B0148 just for simplicity

[swingtan]

IVT more than EGT? I'd hope not....

You need to think about what's going on and look at the bigger picture. The inlet valve is only exposed to combustion temperatures on the combustion chamber side of the valve head, it is also sealed against the valve seat at this time so can transfer heat into the head as well as up the valve stem. Finally, it is cooled with every injection event when liquid fuel is sprayed on the valve head. So the IVT will never be anything like EGT during normal running. The Exhaust valve on the other hand gets full exposure to the exhaust gases as it opens to let out the exhaust, however it also transfers heat up the valve stem and into the head via the seat when closed, so while it's hotter than the intake valve, it's average temp is lower than the EGT.

My advice is to just log IVT, look at what is occurring and then make adjustments. This way you are using the ECM to tell you what it is doing and when it is doing it.

Simon

[auspeed]

what will be the down side if i put 14.63 in all cells of B0143 then 1 as multiplier in all B0146,B0147,B0148 just for simplicity

Did doing that work?