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Author Topic: ME7.1: Ignition Dwell  (Read 120978 times)
Bettonracing
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« on: March 09, 2011, 01:51:28 AM »

Anybody here messing with it? Some of the general documentation refers to it being varied depending on load, as well as some cranking function, but I can't seem to find any tables, or specific information.

I'm also looking for measured spark dwell data (under any condition) if You're willing to share.

Thanks,

H. Kurt  Betton
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silentbob
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« Reply #1 on: March 09, 2011, 03:02:20 AM »

Have a look at the Funktionsrahmen Tony posted. Ignition realisation with dwell time s.o. is described in the section ZUESZ. You can find all the information you need there.
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Bettonracing
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« Reply #2 on: March 09, 2011, 03:37:14 AM »

Have a look at the Funktionsrahmen Tony posted. Ignition realisation with dwell time s.o. is described in the section ZUESZ. You can find all the information you need there.

Thanks. I'll check it out.

Regards,

Kurt
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ABCD
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« Reply #3 on: July 18, 2012, 04:16:43 AM »

Incresing dwell time will increase coil charge storage..

But, beware : if it is increased too much...the currents in ECU may go high and cause damage to ECU
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prj
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« Reply #4 on: July 18, 2012, 05:44:37 AM »

You will also fry the coils or at least severely reduce their service life if you run higher dwell time than needed.

Really, the dwell data should be set as per coil manufacturer specification. Definitely not by "playing with it".
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jibberjive
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« Reply #5 on: July 22, 2012, 12:57:39 AM »

Anyone know if the manufacturer spec dwell time is different between the B5 S4 coils and the 2.0t FSI coils?
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prj
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« Reply #6 on: July 22, 2012, 02:47:13 AM »

For 2.0 TFSI coils, run about 2.0 to 2.5ms depending on voltage.
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jibberjive
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« Reply #7 on: July 22, 2012, 03:07:12 AM »

For 2.0 TFSI coils, run about 2.0 to 2.5ms depending on voltage.
Do you know offhand what the stock B5 S4 is?

Edit:  I guess I could take a look at ZUESZ myself ha.
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s5fourdoor
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« Reply #8 on: January 24, 2013, 05:29:28 PM »

120-day+ thread how goes?

attached is my current xdf which has many tables added for the b5s4 m-box.

specifically, i added multiple tables from my 2012-08-25 release, including KFSZT and FSZTM (relating to ignition dwell)

while researching dwell for 2.0t coils, i found that 2.0t coils run a clean even dwell across all rpm's.

the only variable which changes, according to what i read written by PRJ in a AEB 2.0t thread,
2.0t coil dwell is constant, changing univariately with respect to battery voltage.

here is a screenshot of the dwell you should be running for a 2.0t coil.
also a screenshot for the FSZTM, dwell multiplier related to engine temp (tmot).

please, if someone has a comment that what i'm showing here is wrong, let me know.

my understanding after having read the FR and other threads is that:

2.0t coil dwell should not relate to rpm.  it should also not relate differently based on engine temperature.

can anyone explain the scientific reason why this is for the 1.8t and 2.0t coils?  in fact, from what i gathered, certain implemented multi-spark setups (oem setups) have an actual uni-variate table for the ms of dwell vs batt. volt.

has inductive spark technology improved that much from old-b5 coils to b7/b8 coils?  anyone?

please compare the stock m-box dwell to see what i am saying.  i want feedback, please provide.



« Last Edit: January 24, 2013, 05:33:48 PM by nehalem » Logged
prj
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« Reply #9 on: January 24, 2013, 05:37:56 PM »

The older coils in the older ECU's also ran dwell which was based on RPM and Voltage alone.
Fact is, the resistance that has to be overcome is dependent on cylinder charge too, so from a model standpoint, it makes sense to use lower dwell values for when the cylinder charge is lower and higher values when the cylinder charge is higher.

You should probably look at some MED9 images and see what dwell is set to in those for these coils.
I've been just fairly uniformly setting them to 2.0ms at 13V and have not had issues even at pretty silly boost levels.
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s5fourdoor
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« Reply #10 on: January 24, 2013, 05:42:24 PM »

ok, so: the 2.4ms @ 13v across the board here too much?  the car seems to run fine so far.
if not, can you show a table which has a few more recommended values for kfszt?

thanks prj, as always.     also, it's ok that i de-activated the warmup dwell increase by setting to 1.00 below 51 grad C?
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julex
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« Reply #11 on: January 25, 2013, 07:42:36 AM »

I am in for more info myself as I have 2.0 conversion on my car as well and no problems running stock values.
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prj
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« Reply #12 on: January 25, 2013, 09:21:22 AM »

You will have "no problem" running stock values except:

1. The car will probably not start as well in -25C and below.
2. The coils lifetime will be severely reduced.

The right dwell is "the minimum that is enough". I'd say 2.4 ms at 13v is too much, they are fine at 2.0ms.
Less dwell means longer life for the coil.
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julex
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« Reply #13 on: January 25, 2013, 09:41:14 AM »

But the stock m-box dwell time is well below 2.0ms for most data points (2.0ms until 2000rpms, less beyond that) at 13v with multiplier of 1.5 applied below 50C (which might need a correction based on what you said).

So based on what you said, the dwell time is right for the most part?
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prj
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« Reply #14 on: January 25, 2013, 09:49:25 AM »

But the stock m-box dwell time is well below 2.0ms for most data points (2.0ms until 2000rpms, less beyond that) at 13v with multiplier of 1.5 applied below 50C (which might need a correction based on what you said).

So based on what you said, the dwell time is right for the most part?
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.
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