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Can someone explain (timing related Q)

Old Feb 27, 2011 | 02:53 AM
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Can someone explain (timing related Q)



Can someone explain why the car should have MORE timing when the Coolant Temp is cold?

The percentage modifier gets applied to the timing table - so once the car is warm we have 0% of whatever is in the table...

Forget that they are called EGR - I think thats plain wrong...

This might explain my car knocking when cold, especially if its adding 9* of timing at 2000rpm

Cheers
D.
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Old Feb 27, 2011 | 04:47 AM
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Originally Posted by tephra


Can someone explain why the car should have MORE timing when the Coolant Temp is cold?

The percentage modifier gets applied to the timing table - so once the car is warm we have 0% of whatever is in the table...

Forget that they are called EGR - I think thats plain wrong...

This might explain my car knocking when cold, especially if its adding 9* of timing at 2000rpm

Cheers
D.
According to what I have read, the engine tries to get as high EGT after starting as possible (via increased timing) to get catalysator quickly to its operation temperature to have best catalytic efficiency.

I think if you run test pipe, you can set the increase to 0. You can do it with catalysator as well, but environment wil suffer ;-)

Last edited by xhomm02; Feb 27, 2011 at 04:50 AM.
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Old Feb 27, 2011 | 08:11 AM
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Originally Posted by xhomm02
According to what I have read, the engine tries to get as high EGT after starting as possible (via increased timing) to get catalysator quickly to its operation temperature to have best catalytic efficiency.

I think if you run test pipe, you can set the increase to 0. You can do it with catalysator as well, but environment wil suffer ;-)
Right on the money!!
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Old Feb 27, 2011 | 08:26 AM
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Originally Posted by xhomm02
According to what I have read, the engine tries to get as high EGT after starting as possible (via increased timing) to get catalysator quickly to its operation temperature to have best catalytic efficiency.

I think if you run test pipe, you can set the increase to 0. You can do it with catalysator as well, but environment wil suffer ;-)
I think its timing retard puts more heat in the exhaust. There are cat efficiency tables that retard the timing when the engine is cold. This same cold engine ign advance table is in the CT9A ROMs. Perhaps cold engines need more advance to create a more complete burn. At any rate, I find it comical that both advance and retard tables exist.
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Old Feb 27, 2011 | 01:59 PM
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Originally Posted by xhomm02
According to what I have read, the engine tries to get as high EGT after starting as possible (via increased timing) to get catalysator quickly to its operation temperature to have best catalytic efficiency.

I think if you run test pipe, you can set the increase to 0. You can do it with catalysator as well, but environment wil suffer ;-)


I just asked the same question and I got very much the same answer.
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Old Feb 27, 2011 | 03:48 PM
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Originally Posted by mrfred
I think its timing retard puts more heat in the exhaust. There are cat efficiency tables that retard the timing when the engine is cold. This same cold engine ign advance table is in the CT9A ROMs. Perhaps cold engines need more advance to create a more complete burn. At any rate, I find it comical that both advance and retard tables exist.
Exactly...

I will have to look up the coldstart tables and see what their conditions are..
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Old Feb 27, 2011 | 03:50 PM
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Originally Posted by tephra
This might explain my car knocking when cold, especially if its adding 9* of timing at 2000rpm

Cheers
D.
I know I've told you this already, but mine does the same thing (knocking on load transition when cold) and I've been trying to get rid of it for months, driving me crazy.

Tephra can you get that table(s) for my rom?

55590107 (Your 2010 RA Tephra ROM)

EDIT: I have the main one:

<table name="EGR Timing Advance" address="57359" category="Timing" type="3D" swapxy="true" scaling="Timing">
<table name="Load" address="61778" type="X Axis" elements="9" scaling="Load"/>
<table name="RPM" address="6175e" type="Y Axis" elements="10" scaling="RPM"/>
</table>

Last edited by razorlab; Feb 27, 2011 at 03:56 PM.
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Old Feb 27, 2011 | 04:02 PM
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Another question:

I've been curious about the table labeled "Ignition Warmup Retard" in the Evo 10/RA roms.

With it set to "timing" scaling they read positive timing, with it set to "Min Timing" they read negative timing. The Defs currently out have them as "timing"

Tephra, do you know which is correct?
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Old Feb 27, 2011 | 04:07 PM
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I was always under the impression that this was an absolute value that was mathematically applied as a subtraction to timing... but maybe I'm thinking about the other table.
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Old Feb 27, 2011 | 04:11 PM
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Originally Posted by fostytou
I was always under the impression that this was an absolute value that was mathematically applied as a subtraction to timing... but maybe I'm thinking about the other table.
Yea it would be nice to know what it is. If you set it to 0 with "Timing" then it's -20 with "Min Timing".

I want 0, not -20 so I would like to find out for sure.
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Old Feb 27, 2011 | 05:00 PM
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emailed...
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Old Feb 27, 2011 | 05:01 PM
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Originally Posted by razorlab
Another question:

I've been curious about the table labeled "Ignition Warmup Retard" in the Evo 10/RA roms.

With it set to "timing" scaling they read positive timing, with it set to "Min Timing" they read negative timing. The Defs currently out have them as "timing"

Tephra, do you know which is correct?
Give me the address of the table your talking about and I will look it up...
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Old Feb 27, 2011 | 05:03 PM
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Originally Posted by mrfred
I think its timing retard puts more heat in the exhaust.
What he said.
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Old Feb 27, 2011 | 05:43 PM
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Originally Posted by razorlab
Another question:

I've been curious about the table labeled "Ignition Warmup Retard" in the Evo 10/RA roms.

With it set to "timing" scaling they read positive timing, with it set to "Min Timing" they read negative timing. The Defs currently out have them as "timing"

Tephra, do you know which is correct?
I just looked this up, in your ROM its all 10's right?

The scaling is Timing, but what happens is that under certain conditions the ECU interpolates between this map and the regular timing maps.

After about 50C it doesn't use this map at all...
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Old Feb 27, 2011 | 06:22 PM
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Isn't this the map that controls that?

(for the 2010 maps)

<table name="Percent Low Temp Timing Trim vs Coolant Temp" address="561bc" category="Timing" type="2D" scaling="Percent255">
<table name="Engine Temp" address="61310" type="Y Axis" elements="8" scaling="TempFarenheit"/>
</table>
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