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Rick
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« on: November 29, 2010, 04:53:30 PM »
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Currently I have a standard MAF with 60lb injectors.
My KRKTE is scaled correctly, and this shows in my long and short term trims.
Cruise and idle i'm always at lambda 1. LAMFA is standard, so set to 1 across the board.
On WOT, when LAMFA is set to 1, will the ECU stay in open loop? I suspect not, as on my car with maximum boost of 1 bar, the AFR as soon as i go WOT goes to lambda 0.9.
So, it can't be closed loop anymore?. I'm wondering if this is due to BTS? All BTS maps are currently std. Do they kick in instantly when you reach a certain load due to calculated EGT? 1 bar is obviously more than std boost, so it could be this. I'd need to disable BTS to try.
The other option is that requested LAMFA (1) is not matching actual lambda despite MAF and injector scaling being correct. I'm wondering if I can use KFLF to adjust this. I realise i can adjust fueling using LAMFA and BTS maps but i'd first like the requested lambda to equal actual lamba.
Rick
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ArgDub
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« Reply #1 on: November 29, 2010, 09:46:43 PM »
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Lambda value is selected on the basis of a priority system. The priorities of lambda selection are catalyst protection, component protection(BTS), catalyst heating by secondary air, post-start-warm up... whenever lambts is less than lamfa this one will be overridden by lambts, so when your egts reach tabgbts you lambda starts to follow kflbts. what you describe seems normal to me
Guillermo
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Rick
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« Reply #2 on: November 30, 2010, 02:39:44 AM »
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Hi Guillermo,
I understand the priority system. I was expecting that the lambda would follow LAMFA for longer before following KFLBTS. It seems to happen as soon as I go WOT. This suggests that I am instantly exceeding TABGBTS, which is not the case - a short WOT pull will not raise the EGT enough in reality.
Does the EGT model take this into account, i.e. is there a time delay before calculated EGT starts to rise?
The overall goal I have is to run 0.85:1 WOT for the majority of time, then when the EGT gets too hot have it richen up to 0.7x. If BTS is triggered as soon as I go WOT then I can't see a way of doing this as BTS needs to be set to 0.7x.
Rick
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Rick
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« Reply #3 on: November 30, 2010, 07:18:16 AM »
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After studying the function in more detail, it appears that there is no time delay for KFLBTS, only for the delta function due to retarded ignition angle.
Calculated EGT for compnent protection is drawn from a map. There doesn't seem to be a way of increasing enrichment as EGT increases. Once you are above TABGBTS, you are stuck with the KFLBTS table. This needs tobe rich enough to keep things in check in the worst case scenario
With ignition retard, the further you retard the richer you can run. Not really much use for a modified tune as you don't ever want to be retarding from optimum.
The function I still haven't found is the one that looks at the actual EGT sensor inputs. I've got a feeling that this could be used to trip a further enrichement, which would be ideal.
Rick
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elRey
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« Reply #4 on: November 30, 2010, 10:07:32 AM »
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There doesn't seem to be a way of increasing enrichment as EGT increases. Once you are above TABGBTS, you are stuck with the KFLBTS table. There is such a map. I believe it's FBSTABGM. But it probably doesn't work the way you want it to. It factors the KFLBTS value based on temp above TABGBTS. So, it's not a direct lambda value. |
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« Last Edit: November 30, 2010, 10:21:53 AM by elRey »
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turboskipper
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« Reply #5 on: November 30, 2010, 12:57:15 PM »
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Are you data logging this? Requested lambda and actual lambda should come from a data log, not what you think LAMFA, LAMBTS and so on will give you. If your charge detection and fuel mass parameters are correct you should always have desired lambda equal to actual lambda.
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ArgDub
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« Reply #6 on: November 30, 2010, 10:05:30 PM »
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Rick, elRey is right KFLBTS is scaled by FBSTABGM which is function of EGT, and FBSTABGM is cero when EGT is TABGBTS, so BTS correction is progressive and increases with EGT.
Seems that lambts doesn't cause the increase, maybe there is an accel enrichment function. When throttle is suddenly opened, the airflow will increase more rapidly than the fuel flow due greater inertia of liquid gasoline, which can cause a temporary lean condition, to correct this situation carburators use an accelerator pump, it's logical to think that there is an analogous in me7, but I couldn't find such function yet.
The other option is that your KRKTE not properly calibrated and you see this when you go wot where KRKTE is most significant.
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ArgDub
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« Reply #7 on: November 30, 2010, 10:06:08 PM »
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Are you data logging this? Requested lambda and actual lambda should come from a data log, not what you think LAMFA, LAMBTS and so on will give you. If your charge detection and fuel mass parameters are correct you should always have desired lambda equal to actual lambda.
But, what is the requested lambda?, I mean does anybody know what is the me7 name of the variable you are loggin as requested lambda? |
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« Last Edit: November 30, 2010, 10:13:15 PM by ArgDub »
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elRey
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« Reply #8 on: November 30, 2010, 10:10:19 PM »
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with vagcom, mblock 031 usually shows requested and actual lamdba
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ArgDub
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« Reply #9 on: November 30, 2010, 10:20:03 PM »
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with vagcom, mblock 031 usually shows requested and actual lamdba
I know, but (mblock 031- Lambda specified value) must have a correspondence with some variable in ecu, I would like to know which variable. |
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elRey
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« Reply #10 on: November 30, 2010, 10:24:52 PM »
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lamsbg_w
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ArgDub
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« Reply #11 on: November 30, 2010, 11:05:06 PM »
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Rick
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« Reply #12 on: December 01, 2010, 07:31:03 AM »
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Thanks for the replies, useful info here!
What are the axis for FBSTABGM? One is EGT, but is it calculated or measured EGT? Is there a measurment block which reads calculated EGT in VCDS?
Rick
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elRey
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« Reply #13 on: December 01, 2010, 08:44:01 AM »
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034 and 035
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setzi62
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« Reply #14 on: December 03, 2010, 04:43:59 PM »
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What are the axis for FBSTABGM? One is EGT, but is it calculated or measured EGT? Is there a measurment block which reads calculated EGT in VCDS?
Rick
The FBSTABGM has only one axis and the input is from variable tabgbts_w. This should be calculated EGT. The name of the map is "Faktor BauteileSchutz Temperatur AbGas Modell", i.e. "factor for part protection exhaus gas temperature modeled". Measured with VCDS in group 217 or 214 (if available) are lamsbg_w, lambts_w, lamfa_w, tabgbts_w. |
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