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Author Topic: frm_w and trims  (Read 16196 times)
masterj
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« on: October 15, 2012, 01:30:26 PM »

Hello, everyone!
Couldn't find similar question...
When we log frm_w (lambda control average) is it including the trims (32 group)?

For example in 32 group I have:
IDLE: -1.8%
PART THROTTLE: -5%

My frm_w is something like 0.95xxxx. Does frm_w include IDLE and PART THROTTLE trims or they're then added to this variable in later stage somewhere?
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Bische
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« Reply #1 on: October 15, 2012, 07:16:02 PM »

The way I understand it is that additive trim is applied before fr_w and multiplicative trim is applied after, but since is ~always runs in closed loop, it is always included.

And the only difference between frm_w and fr_w is in frm_w the ZA(forced amplitude) is not included.
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ABCD
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« Reply #2 on: October 16, 2012, 12:06:30 AM »

Hello, everyone!
Couldn't find similar question...
When we log frm_w (lambda control average) is it including the trims (32 group)?

For example in 32 group I have:
IDLE: -1.8%
PART THROTTLE: -5%

My frm_w is something like 0.95xxxx. Does frm_w include IDLE and PART THROTTLE trims or they're then added to this variable in later stage somewhere?

Hello,

Trims are added/multiplied before Lambda correction.
frm_w is fr_w averaged over some time.
for trims calculation frm_w is used.
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masterj
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« Reply #3 on: October 16, 2012, 04:00:30 AM »

Hello,

Trims are added/multiplied before Lambda correction.
frm_w is fr_w averaged over some time.
for trims calculation frm_w is used.

Hm... anyway to disable trims but leave o2 correction? (wideband o2)
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240sxpooter
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« Reply #4 on: October 16, 2012, 06:18:47 AM »

Hm... anyway to disable trims but leave o2 correction? (wideband o2)

 When I want to disable or limit adaption I use

FRAOMN  lower limit of correction factor frao
FRAOMX  upper limit of correction factor frao
FRAORN  reduced lower threshold for frao correction
FRAORX  reduced upper threshold for trao correction
FRAUMN  lower limit of correction factor frau
FRAUMX  upper limit of correction factor frau
FRAURN  reduced lower threshold for frau correction
FRAURX  reduced upper threshold fpr frau correction

 Make all of these =1.0 and you'll never see any changes on group 32 but still have normal O2 correction.
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masterj
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« Reply #5 on: October 16, 2012, 06:59:08 AM »

When I want to disable or limit adaption I use

FRAOMN  lower limit of correction factor frao
FRAOMX  upper limit of correction factor frao
FRAORN  reduced lower threshold for frao correction
FRAORX  reduced upper threshold for trao correction
FRAUMN  lower limit of correction factor frau
FRAUMX  upper limit of correction factor frau
FRAURN  reduced lower threshold for frau correction
FRAURX  reduced upper threshold fpr frau correction

 Make all of these =1.0 and you'll never see any changes on group 32 but still have normal O2 correction.

Thanks Smiley So subfunctions FRAU and FRAO are these trims? Which one is which (idle & part throttle)? Just looked at the FR... Wouldn't it be easier just to set B_NOFRA to 1 ? B_NORKAT?  Huh
« Last Edit: October 16, 2012, 07:02:52 AM by masterj » Logged

240sxpooter
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« Reply #6 on: October 16, 2012, 08:38:45 AM »

Thanks Smiley So subfunctions FRAU and FRAO are these trims? Which one is which (idle & part throttle)? Just looked at the FR... Wouldn't it be easier just to set B_NOFRA to 1 ? B_NORKAT?  Huh

 If you can find it in your image it might be easier Smiley .
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Bische
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« Reply #7 on: October 16, 2012, 10:34:36 AM »

I have changed the codeword NOLRA to disable fuel trims.
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masterj
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« Reply #8 on: October 17, 2012, 06:07:02 AM »

I have changed the codeword NOLRA to disable fuel trims.

I just did the same...
What is interesting is that originally these were disabled (set to 1):
B_norkaz (mixture correction - ignition timing)
B_nofrat (mixture correction - coolant temp)

Should I enable these? How are these set in your ecu file?
« Last Edit: October 17, 2012, 06:08:52 AM by masterj » Logged

masterj
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« Reply #9 on: October 17, 2012, 07:58:51 AM »

One more thing: since we disable TRIMS isn't it better to up a bit o2 sensor regulation boundaries (KFFRMIN & FRMAX)?
What would be good values for upper and lower limits for wb sensor?

BTW: I could easily find FRMAX map in ME7.5 but couldn't find KFFRMIN anywhere... Maybe someone could take a look in ASM and help me to locate this map?
« Last Edit: October 17, 2012, 08:05:01 AM by masterj » Logged

Bische
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« Reply #10 on: October 17, 2012, 10:19:55 AM »

Right after KFMIOP, 16602.
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s5fourdoor
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« Reply #11 on: October 17, 2012, 10:52:28 AM »

OK, just a few brainstorming things I was wondering about.
Totally not trying to play the n00b here, but let's pretend I'm totally new to tuning for a minute.

Why would I ever want to turn off the trims?
   Please correct me if I'm wrong, but trims can also be disabled by basic VAGCOM operation.

Are LTFT's disabled when the MAF is unplugged?


If the "optimal tuning technique" turns off LTFT's after KRKTE and TVUB are close, how do we define close?
Let's define close to be idle LTFT and partial LTFT +/- 1.0%.  Does that seem ok?

Thus, are we implying that a "refined tune" will clean-up all of the real-world fueling after disabling LTFT?

Most of this stuff is procedural and anecdotal.  I'm not a professional tuner, and that's why I'm asking all of this stuff.

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masterj
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« Reply #12 on: October 17, 2012, 10:58:31 AM »

Right after KFMIOP, 16602.


Are you positive about this? In ols file that i have to compare there's one axis 8b and another 16b, at 16602 i see two axes in 16b... Could you tell me this map size? and factors for both axes and map values?
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prj
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« Reply #13 on: October 17, 2012, 12:58:34 PM »

OK, just a few brainstorming things I was wondering about.
Totally not trying to play the n00b here, but let's pretend I'm totally new to tuning for a minute.

Why would I ever want to turn off the trims?
   Please correct me if I'm wrong, but trims can also be disabled by basic VAGCOM operation.

Are LTFT's disabled when the MAF is unplugged?


If the "optimal tuning technique" turns off LTFT's after KRKTE and TVUB are close, how do we define close?
Let's define close to be idle LTFT and partial LTFT +/- 1.0%.  Does that seem ok?

Thus, are we implying that a "refined tune" will clean-up all of the real-world fueling after disabling LTFT?

Most of this stuff is procedural and anecdotal.  I'm not a professional tuner, and that's why I'm asking all of this stuff.

I personally don't turn off the trims ever on narrowband ECU's, and when tuning, I just specify Lambda 0.99 via LAMFA, so that it is open loop the entire time and unable to learn trims.
If tuning wideband however, it is a good idea to disable closed loop when tuning, otherwise it will constantly interfere. Basically the engine must run precise enough off of the MAF alone... the closed loop is mostly there to mask hardware problems and account for aging differences.
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Bische
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« Reply #14 on: October 17, 2012, 07:30:06 PM »

I have been turning off LTFT's but not closed loop, and have been doing this when I have been setting up for FKKVS/FRLFSDP/KRKTE on my returnless wideband 7.5.

It get reaaaally old to dial those maps when you have 1000cc injectors which are basicly non-linear until you get in boost, when you have partial LTFT skewing up the mixture. Does not really make much difference with them on or off now, as my corrections are +-5% under normal driving conditions, well at least over ~1ms effective PW's.

When im happy with my fueling model, im ofcourse turning them on again for the reasons prj mentioned.

Are you positive about this? In ols file that i have to compare there's one axis 8b and another 16b, at 16602 i see two axes in 16b... Could you tell me this map size? and factors for both axes and map values?

IIRC its 4x5 or 5x4, I used the TT damos as reference, I can take a look after work.
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