Motronic experts, stock timing?
#1
Rainman
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Motronic experts, stock timing?
For those of you who are well-versed in the DME, what is the stock, 0* advance, 0* retard, ignition timing BTDC?
I want to know so that in combination with the FQS I can see how much timing I can pull total for my SC project.
Thanks!
I want to know so that in combination with the FQS I can see how much timing I can pull total for my SC project.
Thanks!
Last edited by V2Rocket; 05-06-2009 at 05:34 PM.
#2
Burning Brakes
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Um i think you need to study more about ignition timing. Retarding ignition means ignition happens Xdegrees BEFORE TDC, not after. With the FQS, the only amount you can adjust ignition is by -2.77degrees (ignition occurs 2.77 degrees sooner).
#3
Burning Brakes
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Spencer - If you havn't seen it yet, you should look at frwilk.com He's got probably the best description of how the Bosch Motronic system works. If you dig enough, he probably has the ignition maps there somewhere.
#5
Rainman
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*edit* did a quick read on wikipedia and youre right, very interesting. i guess that the time that passes between say 12* BTDC and TDC is so negligible that it is used for the spark to be able to ignite the fuel mixture. cool stuff.
#6
Race Car
Actually..... the ignition is occurring ~2.77 later using the FQS retard but it still happens BTDC.
say stock is 12 deg BTDC, with the retarded FQS it is now firing @ 9.23 BTDC. It does this throughout the whole map.
It doesn't make too much difference at idle other than lower rpm's, but in boost at higher rpms_ 3 degrees_ can mean the difference between melted pistons and a completely fine engine.
say stock is 12 deg BTDC, with the retarded FQS it is now firing @ 9.23 BTDC. It does this throughout the whole map.
It doesn't make too much difference at idle other than lower rpm's, but in boost at higher rpms_ 3 degrees_ can mean the difference between melted pistons and a completely fine engine.
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#9
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#11
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Hmm, are you changing fueling as well or just timing?
From my understanding of the code it shouldn't have any effect at idle. Perhaps I'm missing a divide in there... Something I'll remind myself to play with.
-Rogue
From my understanding of the code it shouldn't have any effect at idle. Perhaps I'm missing a divide in there... Something I'll remind myself to play with.
-Rogue
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-Rogue
#13
Rainman
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so if retarded timing leads to higher egt's does that mean a premature knock will have a lower egt?
and are there any inexpensive knock-monitoring systems that dont need to plug into the computer, just for like datalogging purposes?
and are there any inexpensive knock-monitoring systems that dont need to plug into the computer, just for like datalogging purposes?
#14
Race Car
melted pistons, valves, rings,plugs,etc..
I used to tune exclusively using an EGT meter, however this was with a fixed (mechanical) distributor so the only changes were due to fueling. It is what I am most familiar with, however I have become pretty familiar with AFR's since then and use them both.
I used to tune exclusively using an EGT meter, however this was with a fixed (mechanical) distributor so the only changes were due to fueling. It is what I am most familiar with, however I have become pretty familiar with AFR's since then and use them both.
#15
Race Car
retarded timing does lead to higher EGT's, however it also helps to prevent detonation. The problem lies with a known timing curve that still gets too high of EGT's, that represents a lean condition that can damage parts.