swingtan
May 12th, 2008, 10:10 PM
Hi All,
Well after spending the past few months working on OL fueling in the E38, I've finally worked out why I was having so many problems. While I've only really tested this in B0143, I think it's a pretty good bet that it applies to B0141 to B0144. Additionally, I think it will also apply to B0146 as it has the same axis values.
Now on to the issue.
All these tables have data that is plotted using Inlet Valve Temp on one axis. Over the past few weeks I've been trying to fine tune fueling, but could not get the logged commanded AFR anywhere near the theoretical levels in the tune. While I could easily get the normal running settings of, say, 14.68:1, I simply couldn't richen up the AFR's when the engine was first started. When I ran my logged data back against the tune file, I should have had richer AFR's when the engine was cold. But the commanded AFR's would always go to 14.68 within a few seconds of starting.
So I started testing what I could and soon realised that if I set the whole table ( B0143 in my case ) I could command any ratio I wanted, so the table worked to some degree. Then I started testing the table, by setting different AFR levels at different IVT temps. The results were interesting to say the least.
It looks like the IVT axis has been off set by 40'c and instead of counting up by 8'c, it counts by 4'c. The combination of the offset and the count up in steps of 8 means that the table only starts having an effect at around 8' and continues up to about 176' at least for me with the current weather. If I measure the IVT and re-plot the axis I get a comparison table that looks like this...
Table Logged
-40 -40
-32 -40
-24 -40
-16 -40
-8 -40
0 -40
8 -36
16 -32
24 -28
32 -24
40 -20
48 -16
56 -12
64 -8
72 -4
80 0
88 4
96 8
104 12
112 16
120 20
128 24
136 28
144 32
152 36
160 40
168 44
176 48
184 52
192 56
200 60
208 64
216 68
Actually, I only logged table data from 80' to 112' but the results were pretty clear cut. Basically, if you take your intended IVT settings and cross reference them in the table, you will be able to fine tune your fuel requirements.
The next test is to see if B0146 suffers from the same problem. So far I've had little success with the modifier tables, but that was before I found the IVT offset issue. Hopefully we can get these tables updated ASAP so we don't need the lookup table.
Simon.
Oh, and thanks to JezzaB, ntae and Hymey for keeping me sane while working on this.
Well after spending the past few months working on OL fueling in the E38, I've finally worked out why I was having so many problems. While I've only really tested this in B0143, I think it's a pretty good bet that it applies to B0141 to B0144. Additionally, I think it will also apply to B0146 as it has the same axis values.
Now on to the issue.
All these tables have data that is plotted using Inlet Valve Temp on one axis. Over the past few weeks I've been trying to fine tune fueling, but could not get the logged commanded AFR anywhere near the theoretical levels in the tune. While I could easily get the normal running settings of, say, 14.68:1, I simply couldn't richen up the AFR's when the engine was first started. When I ran my logged data back against the tune file, I should have had richer AFR's when the engine was cold. But the commanded AFR's would always go to 14.68 within a few seconds of starting.
So I started testing what I could and soon realised that if I set the whole table ( B0143 in my case ) I could command any ratio I wanted, so the table worked to some degree. Then I started testing the table, by setting different AFR levels at different IVT temps. The results were interesting to say the least.
It looks like the IVT axis has been off set by 40'c and instead of counting up by 8'c, it counts by 4'c. The combination of the offset and the count up in steps of 8 means that the table only starts having an effect at around 8' and continues up to about 176' at least for me with the current weather. If I measure the IVT and re-plot the axis I get a comparison table that looks like this...
Table Logged
-40 -40
-32 -40
-24 -40
-16 -40
-8 -40
0 -40
8 -36
16 -32
24 -28
32 -24
40 -20
48 -16
56 -12
64 -8
72 -4
80 0
88 4
96 8
104 12
112 16
120 20
128 24
136 28
144 32
152 36
160 40
168 44
176 48
184 52
192 56
200 60
208 64
216 68
Actually, I only logged table data from 80' to 112' but the results were pretty clear cut. Basically, if you take your intended IVT settings and cross reference them in the table, you will be able to fine tune your fuel requirements.
The next test is to see if B0146 suffers from the same problem. So far I've had little success with the modifier tables, but that was before I found the IVT offset issue. Hopefully we can get these tables updated ASAP so we don't need the lookup table.
Simon.
Oh, and thanks to JezzaB, ntae and Hymey for keeping me sane while working on this.