hymey
July 1st, 2009, 10:42 PM
I have done some research into injector flow rate and trip meter/fuel gauge error. Everyone is aware the maximum hard limit is 63 pounds per hour in the injector flow rate table. So my siemens 63 pound injectors at 58 psi actually flow more like 73lb/hr. So my fuel calcs are 15% out. If I am reading 8L/100kms I am actually well into the 9s.
Another problem we face is that if IFR is low from bigger injectors and we cant raise the IFR number high enough. VE is then low and then g/cyl calculations is also low.Higher IFR is leaner mixture hence higher VE. If we could increase IFR to 73 or more we would have to increase VE which fixes the 15% error and our fuel gauge calcs are correct.
Now the e38 has a lot of untouchable hard limits. IFR tables being one of them, there have been suggestions of increasing the voltage multiplier and IAT multipliers, but this DOES NOT WORK. I have changed all of them to 1.1, 1.5, 3! and still no change so the hard limit is there!.
There is a way though. Tables B0179 and B0180. B0180 we don't have to touch it is only a multiplier and if you are SD anything over 0 is ignored anyway,But I recommend you change this table to 0.1. Now B0179 is very important. I ALWAYS tune cars with this at a constant value. Because as speed increases the mixture richens by a fair bit which is why i had issues with afrs richer in higher gears at speeds over 130km/h. This is a charge temp table, based on the fact that as speed increases VE is more efficient so more fuel is added. Now this has caused me nothing but issues and if anything the mixture needs to be leaned if load increases, which is what I have done with my own car...and numerous other e38s. The table does work. Higher numbers leaner, lower numbers are richer.
Now what I have done with my own vehicle is work out the fuel gauge error of 15%, I initially tuned my car with the whole B0179 table at .50 and B0180 at 0.100. I increased the B0179 table 15% which decreased my VE by 15% which was noticed by both w/b and STFT. I then increased the whole VE table by 15% to correct VE and AFR's. Now my g/cyl is 15% higher and where it should be and I am looking forward to checking the trip meter next tank to see how close it is. I am hoping within two percent if it's still too low I will increase B0179 and the VE. If error is high I will decrease the B0179 table and VE by the correct amount. Atleast I now know and am confident that my g/cyl calculation is correct.
I wanted to share this info in hoping some other guys can try it just to ensure it works across the board. Very promising.
cheers
Joel
Another problem we face is that if IFR is low from bigger injectors and we cant raise the IFR number high enough. VE is then low and then g/cyl calculations is also low.Higher IFR is leaner mixture hence higher VE. If we could increase IFR to 73 or more we would have to increase VE which fixes the 15% error and our fuel gauge calcs are correct.
Now the e38 has a lot of untouchable hard limits. IFR tables being one of them, there have been suggestions of increasing the voltage multiplier and IAT multipliers, but this DOES NOT WORK. I have changed all of them to 1.1, 1.5, 3! and still no change so the hard limit is there!.
There is a way though. Tables B0179 and B0180. B0180 we don't have to touch it is only a multiplier and if you are SD anything over 0 is ignored anyway,But I recommend you change this table to 0.1. Now B0179 is very important. I ALWAYS tune cars with this at a constant value. Because as speed increases the mixture richens by a fair bit which is why i had issues with afrs richer in higher gears at speeds over 130km/h. This is a charge temp table, based on the fact that as speed increases VE is more efficient so more fuel is added. Now this has caused me nothing but issues and if anything the mixture needs to be leaned if load increases, which is what I have done with my own car...and numerous other e38s. The table does work. Higher numbers leaner, lower numbers are richer.
Now what I have done with my own vehicle is work out the fuel gauge error of 15%, I initially tuned my car with the whole B0179 table at .50 and B0180 at 0.100. I increased the B0179 table 15% which decreased my VE by 15% which was noticed by both w/b and STFT. I then increased the whole VE table by 15% to correct VE and AFR's. Now my g/cyl is 15% higher and where it should be and I am looking forward to checking the trip meter next tank to see how close it is. I am hoping within two percent if it's still too low I will increase B0179 and the VE. If error is high I will decrease the B0179 table and VE by the correct amount. Atleast I now know and am confident that my g/cyl calculation is correct.
I wanted to share this info in hoping some other guys can try it just to ensure it works across the board. Very promising.
cheers
Joel