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Author Topic: ME7.1: Ignition Dwell  (Read 101942 times)
julex
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« Reply #15 on: January 25, 2013, 09:56:59 AM »

I would not be so sure.
Log the actual dwell during a WOT pull.
On the 1.8T's it was around 4ms for the Hitachi coils. But I am not really sure about the 2.7TT stock ones.
I just bought 6 brand new coils for my RS, because they are not that expensive and my POSes are fine.

The variable you want to log is tsrldyn.

Thanks.
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s5fourdoor
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« Reply #16 on: January 25, 2013, 12:22:56 PM »

Is tsrldyn the variable which the FR calls szout_w?  Section ZUESZ in FR, description says "dwell time".

Any idea?
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julex
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« Reply #17 on: January 25, 2013, 03:07:00 PM »

I logged tslrdyn and it indeed leans on 3.5ms limit a lot especially when "stepping on it". I suspect it is the same with the 2.0 table above, the coils probably charge longer than the table says. I would like to see what TSMX on TFSI ecu is like, it would us more idea as to what charge time they run up to.
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s5fourdoor
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« Reply #18 on: January 25, 2013, 03:17:35 PM »

I logged tslrdyn and it indeed leans on 3.5ms limit a lot especially when "stepping on it". I suspect it is the same with the 2.0 table above, the coils probably charge longer than the table says. I would like to see what TSMX on TFSI ecu is like, it would us more idea as to what charge time they run up to.

So is this evidence for or against the stock table values and elimination of cold-start multiplier?  Thoughts?  I'm reading it as evidence against the stock table values.
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catbed
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« Reply #19 on: January 25, 2013, 03:32:24 PM »

moved my post.
« Last Edit: January 27, 2013, 11:38:28 PM by catbed » Logged
julex
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« Reply #20 on: January 25, 2013, 09:10:48 PM »

So is this evidence for or against the stock table values and elimination of cold-start multiplier?  Thoughts?  I'm reading it as evidence against the stock table values.

What I am saying is that there is much more to it than just that table. I wouldnt be surprised if tfsi ecu wasn't driving its coils at very similar dwell time as 2.7 seeing that the table is just a starting point for dwell calculations.
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prj
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« Reply #21 on: January 26, 2013, 07:18:19 AM »

What I am saying is that there is much more to it than just that table. I wouldnt be surprised if tfsi ecu wasn't driving its coils at very similar dwell time as 2.7 seeing that the table is just a starting point for dwell calculations.

It seems you are making a habit of questioning everything I say.
So far I've made only one mistake, and that's telling you to log tsrldyn instead of szout_w, but it's not too important, since you can derive szout_w from tsrldyn using the KFSZDUB table, and at 14V it's 1.0 anyway.

In a 2.0TFSi binary the following is set:
TSMX is set to 3.5
CW_SZTRL is set to 0, meaning only load corrected dwell is used so SZOUT is tsrldyn corrected by KFSZDUB.
This also means that tsrldyn is equal to KFTSRL * FSZTM.
KFTSRL values are:


KFSZDUB values in 2.0 TFSI MED9 use 12.0 as it's center point:


FSZTM with a hot engine is 0.996.
This means the dwell is between 1.9 and 2.4ms at 14 volts in normal operating conditions.
I have personally tested these coils to give a good spark at 2.0ms uniformly throughout the range on engines running more than 300 hp per liter - the factory dwell time is conservatively high.

2.0 TFSi running similar dwell time? I don't think so.
« Last Edit: January 26, 2013, 07:28:45 AM by prj » Logged

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julex
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« Reply #22 on: January 26, 2013, 08:34:12 AM »

It seems you are making a habit of questioning everything I say.
[Awesome stuff]

Prj, I apologize if I come across is way. In no way do I want to question what you say, so far you've been of great help on any subject I asked questions about, I bow to your expertise.

What would be the best course of action for 2.0tfsi converted M-box then? Just cap TSMX to 2.0 - 2.5 and call it a day?
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prj
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« Reply #23 on: January 26, 2013, 09:35:01 AM »

You could do that as a quick hack, and truth be told, I've done that in a pinch in the past.
But it would not be correct, because it is not quite following the model and KFTSDYN gets applied after TSMX as a multiplicative addition.
Looking at the ME7 diagrams now, szout_w is not the value to log, it's szrl_w in case of ME7. Was looking at MED9 earlier. That's two mistakes.

The ME7 ZUESZ diagrams are a huge clusterfuck, it is much better in MED9.
As I understand FSZTM*KFSZT is one source, but this is not used in 2.7TT (CW_FUBND=0).

What is used is KFTSRL as base, then corrected through a bunch of things.
You can see that already the base opening time is too high 3.0ms almost to redline.

After KFTSRL it gets corrected during dynamic load, and this is where the extra dwell comes from.
The factor is FTSDRLW.

Then it gets corrected for engine temp (FSWTM), but this is 1 after 50C.
It then goes through a battery voltage correction (KFSZDUB), this is 1 at 14V.
Finally it is corrected for RPM gradient - KFTSDYN... this can have a small influence, but mostly this will be at 1.

I think if you want to transfer it over right, DTSDRLW should be forced to 1 and KFTSRL, FSWTM, KFSZDUB should be filled from KFTSRL, FSZTM, KFSZDUB from MED9.
« Last Edit: January 26, 2013, 09:38:12 AM by prj » Logged

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s5fourdoor
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« Reply #24 on: January 26, 2013, 10:28:29 AM »

OK.  I'm glad somebody finally admitted we don't have the model for it.
I've been tearing through these documents and there isn't shit that's comprehensive for ME7.1     Thanks for the relative insights PRJ.
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s5fourdoor
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« Reply #25 on: January 26, 2013, 10:31:13 AM »

Where is DTSDRLW?  I found DTSDRL in your auto-M xdf.
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prj
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« Reply #26 on: January 26, 2013, 10:34:20 AM »

OK.  I'm glad somebody finally admitted we don't have the model for it.
I've been tearing through these documents and there isn't shit that's comprehensive for ME7.1     Thanks for the relative insights PRJ.

You've probably been looking at the Alfa FR.
It's very primitive there.

A very good explanation is in the 1.8T German FR along with the diagrams.
There is a lot of text explaining how it all works.

Of course if you can not speak German, it might be a bit hard to read...

Where is DTSDRLW?  I found DTSDRL in your auto-M xdf.

You could FF DTSDRL (if you are sure you have the right offset), that should essentially accomplish the same thing as setting DTSDRLW to 1.
DTSDRL is activation threshold.
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s5fourdoor
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« Reply #27 on: January 26, 2013, 10:41:59 AM »

OK.  The DTSDRL i'm seeing on the m-box is 2.60.  I will definitely check out the 1.8t german FR, and luckily I'm ok at speaking/reading Deutsch.

I'm still not super clear on all of the changes, so I'm going to continue reading the FR and assembling a master list of tables.  I'd prefer not to make a sequence of uneducated changes.
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jibberjive
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« Reply #28 on: January 26, 2013, 11:16:24 AM »

...
« Last Edit: May 10, 2013, 11:50:09 PM by jibberjive » Logged
prj
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« Reply #29 on: January 26, 2013, 11:37:15 AM »

OK.  The DTSDRL i'm seeing on the m-box is 2.60.  I will definitely check out the 1.8t german FR, and luckily I'm ok at speaking/reading Deutsch.

I'm still not super clear on all of the changes, so I'm going to continue reading the FR and assembling a master list of tables.  I'd prefer not to make a sequence of uneducated changes.

Well I already gave you a list of tables, and what you need to change.
Feel free to look at it yourself though and broaden your understanding of the subject.
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