Audi RS2 trigger error 1.1.81

[GintsK]

Not much slower burning when comparing to our usual rich mixtures. But density are lower, flame initial forming takes longer (initial pressure rising after spark). And advance numbers can be very high. Main reason of low advance values on OE is NOx I think.

We also have issues to set high advance numbers for cruising. Especially on bigger engines. Cruising speeds of bigger ones starts even as low as 1500Rpm - too close to idling speed. As result advance table becomes too sloppy. And it can lead to bad jerking in transition area.
Solution here can be some kind of damper for advance what prevent from fast advance changing. Some ECUs have this feature.

[mattias]

The case of the VW engine has something working in it's favor, the high C/R allows a good homogenised mixture that helps a lean and slow burn to take place,  sometimes I wonder how much a degree or two can make .. there might be little difference between 30 and 35 degrees advance in some situations.  In any case the older Audi 20 valve turbo engine has less C/R to handle the boost but like most 4 valve/cyl engines it's superior to older 2 valve/cyl engines (unless you're comparing it to old high C/R racing engines).

I am too looking for a feature where there is a separate idle advance table, or even just a single advance number perhaps affected by coolant temperature. This is very common in other systems and would allow a better driving experience and fuel consumption with engines that utilise the low rpm for driving. I'll make a wish.

[GintsK]

I am too looking for a feature where there is a separate idle advance table, or even just a single advance number perhaps affected by coolant temperature. This is very common in other systems and would allow a better driving experience and fuel consumption with engines that utilise the low rpm for driving. I'll make a wish.

Key question is how ECU will migrates from main table to idle advance and back.

I assume 20VT could be happy with even more than my 45 degries on VW due to lower CR.

[Jamo]

Ignition looks about right to me the engine is a 2.5 stroker the same as mine

Is it the lean cruise lambda of 1.05 that makes 38 degrees possible?

It's certainly interesting because I managed better than Motronic did on an Audi S4  using only 28-30 degrees timing, lambda 1.02.
It was not stock, 630 cc/min injectors, tubular exhaust manifold, larger turbo, larger intercooler, etc..

It's a diesel block / petrol head with a longer stroker 86.4 vs 95.5 and lower CR because of the custom pistons

[mattias]

I assume 20VT could be happy with even more than my 45 degries on VW due to lower CR.

There are two sides to the coin, I'm not sure it will work out like that, with lower C/R you can end up with less squish area and less turbulence to create a homogenised air/fuel mixture that won't burn as well, creating less power.

[billman]

would the 1.1.85 FW version cure the trigger error on the RS2? Or is it for other Audi engines?

[1.1.85] - not released yet

    * auditrigger divby2 changed to divbyANY
          o toothrel_missing=01 for divby2
          o toothrel_missing=19 for divby26
          o toothrel_missing=1a for divby27
          o with auditrigger 11000 RPM could be reached earlier (in benchtests) using divby27. Not 25500 RPM as with lower toothcounts, but sufficient.
          o note: auditrigger divby3 (which is used in hundreds of 135 tooth audi engines) maintains compatibility
          o question: what about Nissan 360 impulse dividing?

[mattias]

There was a false secondary trigger warning, which should not cause any issues (only warn) with 1.1.80 and 1.1.81. I've updated to 1.1.84 on a S4 (AAN) and S2 (3B with 60-2 trigger from more recent VW/Audi engine), they don't warn now.
You could try 1.1.84 to avoid false warnings for secondary trigger, to see the real ones. You must use latest VemsTune to make upgrade simple, new SafetyMode settings are automatically set.

The changes for 1.1.81 is to support other dividers for triggers with many teeth, but different count than Audi 5 cyl (135), now supports 130 tooth on Porsche 4 cyl by using different dividers.

[AVP]

whenever a fw version upgrade is done should one always recheck the timing with a strobe light timing gun?

or should this be done when a trigger setting is changed?

[rob@vems.co.uk]

Always check when you change firmware

[AVP]

$^&£
this means that i will have to end up buying a gun...

[billman]

There was a false secondary trigger warning, which should not cause any issues (only warn) with 1.1.80 and 1.1.81. I've updated to 1.1.84 on a S4 (AAN) and S2 (3B with 60-2 trigger from more recent VW/Audi engine), they don't warn now.
You could try 1.1.84 to avoid false warnings for secondary trigger, to see the real ones. You must use latest VemsTune to make upgrade simple, new SafetyMode settings are automatically set.

The changes for 1.1.81 is to support other dividers for triggers with many teeth, but different count than Audi 5 cyl (135), now supports 130 tooth on Porsche 4 cyl by using different dividers.

do you think this strange shutter i got the other day was because of the 1.1.81 error and the fact that i didnt had "Just show" on vems tune?

[mattias]

Yes, if you don't have "just show (default)" in the setting for what to do with a bad trigger event on the secondary trigger, then you'll actually experience a consequence, and the engine will not run right.  The engine should run just fine if you just use that setting. An upgrade to 1.1.84 is a very easy one if you're already at 1.1.81, if you used much older firmware like 1.1.27 then I'd definately advice using a strobe light to verify correct ignition timing.

[billman]

I believe AVPs timing was the same for 1.1.27 to 1.1.81 am i right?

[AVP]

very tiny difference

on 1.1.27 i used 56 and on 1.1.81 it has to be between 56.5 and 57