Speed density users, accel enrichment tip
Apr 11, 2009, 10:19 AM
#1
Evolved Member
Thread Starter
Speed density users, accel enrichment tip
I and another SD user have noticed that whilst the engine doesn't stumble, the throttle tip in can briefly go lean (16:1 on wideband, and a dropout to lean on narrowband). This is because the MAP sensor doesn't get advance warning of the inlet manifold filling spike that the MAF sensor gets, it is just a fraction of a second behind.
So to experiment I moved the "Asynch_VS_TPSDELTA" into RAM and tried a variety of adjustments.
The initial values are about 7 or 8 for the lower bins, adding 8 to the whole table was about right, with an extra 4 nearly there and an extra 12 being a bit too much so it would richen a little excessively, although without visible smoke. It feels a bit crisper too.
I'm not sure this table is defined for all ROMs, but some of mattjin's threads do contain info IIRC.
Note that you should never use acceleration enrichment to cover up a lean base map. Most users wouldn't even notice this, but it has been something I've been meaning to fix and when another user had also noticed it I thought it would benefit from correction.
Note also that you won't see any difference on your IPW logs when you alter this, as it is not part of the normal injector pulse widths, but an extra, hence the "asynchronous".
So to experiment I moved the "Asynch_VS_TPSDELTA" into RAM and tried a variety of adjustments.
The initial values are about 7 or 8 for the lower bins, adding 8 to the whole table was about right, with an extra 4 nearly there and an extra 12 being a bit too much so it would richen a little excessively, although without visible smoke. It feels a bit crisper too.
I'm not sure this table is defined for all ROMs, but some of mattjin's threads do contain info IIRC.
Note that you should never use acceleration enrichment to cover up a lean base map. Most users wouldn't even notice this, but it has been something I've been meaning to fix and when another user had also noticed it I thought it would benefit from correction.
Note also that you won't see any difference on your IPW logs when you alter this, as it is not part of the normal injector pulse widths, but an extra, hence the "asynchronous".
Last edited by jcsbanks; Apr 11, 2009 at 10:21 AM.
Apr 11, 2009, 01:40 PM
#2
Hello Banks,
I have the same problem using alky injection, although my alky kit is driven by maf signal.
I will try incresing my accel enrichment, but I have the values put at 1.43 (not 7-8) as you mentioned, which is confusing me a bit.
Any ideas?
Tks
I have the same problem using alky injection, although my alky kit is driven by maf signal.
I will try incresing my accel enrichment, but I have the values put at 1.43 (not 7-8) as you mentioned, which is confusing me a bit.
Any ideas?
Tks
Apr 11, 2009, 03:50 PM
#7
Evolved Member
Thread Starter
grayw, the 88570008 address is in the MLR thread where I posted my latest 88570008, I included the xml.
BarryC, grayw was has tested 90550001 SD and found it fine.
BarryC, grayw was has tested 90550001 SD and found it fine.
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Apr 12, 2009, 02:22 AM
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Apr 12, 2009, 02:39 AM
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could yourself or GrayW post up how to calculate the correct tables for SD or if its already posted send me the link tried to search for the info,
Apr 12, 2009, 03:47 AM
#13
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Thread Starter
ok I understand that but please bear with me on this till I fully understand how you come up with the correct values to put into the calibration table,
the calibration table is the raw values used from the MAF logs i.e. if I look at my logs I can see that at a certain load the MAP (KPA) can be different values for the same load, I opened the file in evoscan maptracer and asked for the average ie 40 load = 56.7 KPA
are these the values to use in the calibration table ??
then adjust the VE vs RPM percentage to fine tune the correct AFR for a certain load (MAP)
the calibration table is the raw values used from the MAF logs i.e. if I look at my logs I can see that at a certain load the MAP (KPA) can be different values for the same load, I opened the file in evoscan maptracer and asked for the average ie 40 load = 56.7 KPA
are these the values to use in the calibration table ??
then adjust the VE vs RPM percentage to fine tune the correct AFR for a certain load (MAP)
If you have 40 load at 56.7 kPa at say 2000 RPM, then you can have a MAP calibration and VE top row value of 56.7 kPa, and a bottom road value of 40 load. If you are not going to use a top row value of 56.7 kPa, but want something near like 60kPa, then the bottom row must be scaled in proportion so you'd have 42.3 load in the bottom row. Your main work will be in the MAP calibration and VE table. The calibration is precalculated and is the scaling you use for the top row (x/3 for JDM 3 bar MAP), the VE is calculated or estimated as discussed in this paragraph.
The RPM VE table is a correction for low and high RPM drops in VE. I use about 90% at idle and at high RPM, with 100% from 1500 to 5500 RPM, which works well on my stock turbo MIVEC engine.
If you were going to use 90% RPM VE at 1000 RPM for idle, and your found you had 40 load at 56.7 kPa, then your MAP calibration and VE table top row 56.7kPa would have bottom row of 40*100/90 = 44.4, this it because at this RPM it is going to be multiplied by the 90% RPM VE value to give you your desired 40 load. It works, sounds a bit odd, but it is much easier than tuning a large 3d table, and gives better trims than the MAF sensor and a nice smooth drive.
If you prefer an equation:
Load = [ MAP(kPa) lookup of MAP calibration and VE table ] * [ RPM lookup of RPM VE table / 100 ]
