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Author Topic: MED 9.1 basics  (Read 319015 times)
overspeed
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« Reply #180 on: July 17, 2015, 09:22:12 AM »

UHm... make a lot of sense,

I tried some experiencies with ME7 (don´t know if it aplies here too), with stock KFFDLBTS it was allways richer than KFLBTS even without any knock event (KFZWOP and KFZW stock too, with Petrobrás Podium fuel - 95 oct RON and little more load/boost), after that I make KFFDLBTS all "0" and lambda follows KFLBTS (as I wanted)... in MED9 would I expect some other behavior ?
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Rick
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« Reply #181 on: July 18, 2015, 05:39:29 AM »

Some ECU's are coded to work on the difference between basic ignition angle efficiency and retarded ignition angle efficiency.  In this case with no retard DLBTS and KFFLDBTS will not kick in.  Some ECU's look at ignition angle efficiency in absolute terms, i.e difference in efficiency from KFZWOP and zwout.  Here you will get an AFR of KFLBTS multiplied by the relvant values in KFFDLBTS and DLBTS.   

Correctly tuned, you will have your targeted AFR in normal conditions, and a richer AFR if ignition timing retards from your basic ignition angle.

Rick
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overspeed
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« Reply #182 on: July 18, 2015, 05:55:17 AM »

Great, how is it coded?

some relation with wideband/narrowband or those with/without EGT sensor?
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majorahole
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« Reply #183 on: July 18, 2015, 02:55:07 PM »

Any idea then why VAG is using BTS all the time at stock?
Initially I tuned by using LAMFA as the main fuelling map, however it kept falling back to BTS so tuning it that way was pretty futile.
Also TAVVKBTS defaults to 1268.5°C (FFFFh) which sounds fishy as FR specifies 900°C for it.

"Bad quality fuel" doesn´t exist where I live (98 RON is bare minimum), so the protection isn´t absolutely mandatory.
I had TAIKRBTS at 800°c stock. I raised that up to 850. I also assume u knocked the LAMFA delay down to 0 too??
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Nottingham
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« Reply #184 on: July 18, 2015, 04:27:44 PM »

I had TAIKRBTS at 800°c stock. I raised that up to 850. I also assume u knocked the LAMFA delay down to 0 too??

TAIKRBTS and TAVROBTS are the only two values which are not set to maximum by default.
TAIKRBTS default to 800°C while TAVROBTS default to 1200°C. All the other values are 1263°C (FFFFh), which I assume means disabled.
TLAFA you mean? Haven´t touched it (2.7 seconds).
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majorahole
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« Reply #185 on: July 18, 2015, 04:35:19 PM »

TAIKRBTS and TAVROBTS are the only two values which are not set to maximum by default.
TAIKRBTS default to 800°C while TAVROBTS default to 1200°C. All the other values are 1263°C (FFFFh), which I assume means disabled.
TLAFA you mean? Haven´t touched it (2.7 seconds).
ya, if you leave it stock LAMFA isn't used until the time has passed, i was using bts as main fueling too until I adjusted the LAMFA and removed the timer
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Nottingham
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« Reply #186 on: July 18, 2015, 04:37:11 PM »

ya, if you leave it stock LAMFA isn't used until the time has passed, i was using bts as main fueling too until I adjusted the LAMFA and removed the timer

Great, thanks for the info Smiley
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prj
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« Reply #187 on: July 18, 2015, 05:17:49 PM »

Correctly tuned, you will have your targeted AFR in normal conditions, and a richer AFR if ignition timing retards from your basic ignition angle.

Rick

Sums it up well with one sentence.

Everyone who disables BTS or uses it for fuel all the time is not tuning correctly as the ECU manufacturer intended, as simple as that.
You can always treat the ECU as garbage-in, garbage-out, but you will have better (safer) results if you use the intended mechanisms correctly.
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prj
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« Reply #188 on: July 18, 2015, 05:19:26 PM »

so a bad fuel will not make EGT diferent for ECU.

Incorrect, calculated EGT (of course) depends on ignition angle efficiency, just as actual EGT.
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Nottingham
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« Reply #189 on: July 18, 2015, 05:35:03 PM »

Sums it up well with one sentence.

Everyone who disables BTS or uses it for fuel all the time is not tuning correctly as the ECU manufacturer intended, as simple as that.
You can always treat the ECU as garbage-in, garbage-out, but you will have better (safer) results if you use the intended mechanisms correctly.

So is this correct:

Calculated EGT < TAIKRBTS = LAMFA is used
Calculated EGT > TAIKRBTS = KFLBTS is used to enrich the mixture

If so should the TAIKRBTS be increased and TLAFA set to zero in order to stay in LAMFA for fueling?
And BTS maps are kept as a safety measure in case the EGTs or the timing retardation increases to dangerous levels (because of crappy fuel for example)?

Also what are the most common reasons for high EGTs on these engines?
The EGTs are high despite the 0.8 lambda, moderate boost and non-restrictive exhaust.
Obviously the EGT calculations have been knocked off by the downpipe alone, however the difference shouldn´t be too big.
« Last Edit: July 18, 2015, 05:39:00 PM by Nottingham » Logged
nyet
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« Reply #190 on: July 19, 2015, 12:49:46 AM »

So is this correct:

Calculated EGT < TAIKRBTS = LAMFA is used
Calculated EGT > TAIKRBTS = KFLBTS is used to enrich the mixture

No absolutely not. They are calculated separately. The lower one wins. PLEASE review the FR and the s4 tuning page again

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Nottingham
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« Reply #191 on: July 19, 2015, 02:00:43 AM »

I am just trying to find out what triggers the change from LAMFA to KFLBTS for fuelling?
I assume it´s TAIKRBTS since KFLBTS is used all the time even when fully stock.
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prj
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« Reply #192 on: July 19, 2015, 03:27:57 AM »

I am just trying to find out what triggers the change from LAMFA to KFLBTS for fuelling?
I assume it´s TAIKRBTS since KFLBTS is used all the time even when fully stock.

There are ~10 different temperature triggers. If any temperature goes over it's temperature trigger, BTS is activated.
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« Reply #193 on: July 19, 2015, 02:50:04 PM »

I am just trying to find out what triggers the change from LAMFA to KFLBTS for fuelling?

Again, this is the wrong way of looking at how BTS works.
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Nottingham
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« Reply #194 on: July 19, 2015, 03:20:03 PM »

Ok so basically you´re saying:

- Using any BTS map for fuelling is wrong
- Changing BTS activation thresholds is wrong

So please do explain how the hell one does one force the ECU to use LAMFA then?
I could set the LAMFA map to 0.6 and still the ECU won´t use it.
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