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Author Topic: ZWMIN section  (Read 5765 times)
masterj
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« on: June 05, 2012, 08:08:57 AM »

Bonjour!  Smiley
So here I was trying to analize ZWMIN section of document and then it struck me -> What DZWDYN map does? In english doc it is "Spark advance for burning-limit angle at tip-in". So, if we set CWKHZW bit2 then ECU tries to advance timing based on engine temp or what (I think that there are already map that does it - KFZWSTTM)? What does "tip-in" mean? And where do we set "burning-limit"?

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silentbob
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« Reply #1 on: June 05, 2012, 12:51:05 PM »

KFZWMN contains the latest possible ignition angle before the exhaust gases get too hot or the late ignition angle causes misfire (=burning limit).
It's a key map for engine safety and driveability.

TIP IN means that you step on the accelerator in standstill with no gear engaged. This function is there to protect the cat from overheating by advancing the minimum ignition angle if you do this over and over again.
« Last Edit: June 05, 2012, 12:54:17 PM by silentbob » Logged
masterj
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« Reply #2 on: June 05, 2012, 03:36:07 PM »

KFZWMN contains the latest possible ignition angle before the exhaust gases get too hot or the late ignition angle causes misfire (=burning limit).
It's a key map for engine safety and driveability.

TIP IN means that you step on the accelerator in standstill with no gear engaged. This function is there to protect the cat from overheating by advancing the minimum ignition angle if you do this over and over again.

Great explanation! Thank you very much, silentbob!

BTW: Since I have no cat in my car (no resonators either), can I safely turn off this protection?
I'm planning to do something like this:
Code:
CWKHZW = 0
DNTIPDYN = 12700
FZWKHMX = 0
TTIPINEN = 2.25
TTIPINON = 0
KFZWMNKH = -96s
KFZWMNST = -96s
KLZZWMNST = 0s
ZWSPTIP = 655.35
DZWDYN = 0s

Also I think I should leave these since they are there to execute protection when zwist < zwmnms. From diagram in 670 (english FR) page I see that these to maps control trigger mechanism of ignition angle protection when ignition angle is lower than lowest possible. Am I right?
Code:
TVZWMSA
TVZWMSE

Also I'm leaving this map stock (ignition angle retardation based on exhaust gases (or intake air) mass?):
Code:
DZWAML (it is set to 0.75 which is max anyway based on 670 page of FR)

The reason I'm doing all this is to simplify control of minimum possible ignition angle and leave only one protection when KFZW < KFZWMN.
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kalachim
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« Reply #3 on: January 23, 2021, 04:52:47 PM »

Hello,
I know that topic is very old however few questions to help me understand.

I would like to find what is limiting my timing retard at decelerating
KFTVSA --> everywhere 2,5s, KFZWOP/2  -22degrees, KFZWMN -31, KFZWMS -96, and still maximum retard is -24 which I achieve, i would like to go even lower...

Maps below were never touch by me, I want to understand them first.

KFZWMNKH map? I have it originally zero'ed, should I put there -96?
DNTIPDYN - Switch-on threshold speed dynamics for tip-in offset to the latest ignition angle = 12700 will never allow this switch to go ON? (rpm will never drop that fast?)
CWKHZW = 0? why?
TTIPINEN = Time to query for frictional connection with speed dynamics, I have it zero, what does it do?
TTIPINON = Switch-on time Tip-In offset to the latest ignition angle, I have it = 2s
KLZZWMNST = honestly I don't understand values in this map  46080,0000   3585,0000   27394,0000   55554,0000   24834,0000   27907,0000   27139,0000   45060,0000 ?? seconds ?? "KL Time constant for curtailment of ZW limitation in post-start"
ZWSPTIP = I have originally 1s.  "Time to activate the TIPIN offset to the latest ignition angle", maxing the value will not let ecu to activate the limit?
DZWDYN = it is grad KW units, however it is 0 when engine is warm.
TVZWMSA = Time until transition to permanent late limit, fabric 0,5s, to turn it off I should increase this value right?
TVZWMSE = Time until transition to dynamic delay limitt, fabric 0,5s, to turn it off I should increase this value right?

Maybe I should look for something else?


Other problems are:
When decelerating in gear, there are pops, when I push the clutch pedal (still decelerating, i just want to switch gear), poping stops, so the car never pops while switching gears.
(551D ecu)
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elRey
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« Reply #4 on: October 10, 2021, 01:04:05 PM »

In my M37.5, there is a hard coded limit that zwout is compared to => #4Eh = -24*
No map for it, it's a hardcoded limit in numerous places. SY_WMIN in FR doc.

I had thought I found them all and reduced by 1 => #4Dh, but no change.

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