Base Timing Advanced 1* From Spark Map at Idle

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jbh
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Base Timing Advanced 1* From Spark Map at Idle

Post by jbh »

I have an interesting issue with my ignition timing at idle.

I'm set at 10* base angle offset. However, at idle, the truck is running at 11* timing. It seems that anything off idle, the 1* timing discrepancy disappears.

Here are a few screenshots that show this issue as well as my settings.

Any input would be much appreciated. Thank you.
image.png
image (1).png
image (2).png
jbh
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Re: Base Timing Advanced 1* From Spark Map at Idle

Post by jbh »

Two more screen shots.
image (3).png
image (4).png
jbh
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Re: Base Timing Advanced 1* From Spark Map at Idle

Post by jbh »

Here is my MSQ and an older datalog.
22rte spark issue.msq
2016-04-19_13.44.04.msl
jsmcortina
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Re: Base Timing Advanced 1* From Spark Map at Idle

Post by jsmcortina »

With a trigger angle like that, by design, the lowest you can go is 1 deg more than trigger angle.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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jbh
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Re: Base Timing Advanced 1* From Spark Map at Idle

Post by jbh »

I don't quite understand.

The Timing Map is calling for spark at 10* BTDC. However, I am actually getting spark at 11* BTDC. I'm curious as to why there is this discrepancy, and how to correct it.

Thanks,

Jesse
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Re: Base Timing Advanced 1* From Spark Map at Idle

Post by jsmcortina »

Mechanically your distributor is sending a signal at 10BTDC. By design the code will only allow you to go down to 1 deg earlier (more advanced) than that.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
Matt Cramer
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Re: Base Timing Advanced 1* From Spark Map at Idle

Post by Matt Cramer »

jbh wrote:I don't quite understand.

The Timing Map is calling for spark at 10* BTDC. However, I am actually getting spark at 11* BTDC. I'm curious as to why there is this discrepancy, and how to correct it.

Thanks,

Jesse
I put together a detailed description of the timing limitations in basic trigger - you can see this here:

http://www.msextra.com/forums/viewtopic ... 01&t=63936
Matt Cramer -1966 Dodge Dart slant six running on MS3X
mazdaspeed
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Re: Base Timing Advanced 1* From Spark Map at Idle

Post by mazdaspeed »

Great description matt. So the best agles for basic trigger to be thd most stable and most range will be around 60° btdc???

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