I have minor detonation right after 3rd +4th gear
12-14-2001, 01:42 AM
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I have minor detonation right after 3rd +4th gear
It's right after the rpms drop in 3rd from second.It does the same in 4th.The sound is the "spark knock" or similar to "rocker arm noise".Its just started with my latest chip.It is very,very,very minor though.I know the sound very well.My brother has a 2.2l turbo daytona.He bumped up the boost and that lean knock is all you would hear.He has went through 4 motors by now.He's not very smart.Anyway,any ideas?
12-14-2001, 08:51 AM
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I have found from all of my "experimentation" with spark advance that the first place I seem to detect "knock" (when I just cross the line of too much spark advance) is during the upshift. Sounds like you are finding the same thing.
I am debating about writing an "upshift retard routine" for my SD to see if I can get a few degrees more. But it really is showing that I have too much spark advance and my engine is telling me to "back it off" a bit.
What is your "effective" total spark advance right now? I am finding that with my stock L98 heads 28-29* is about the MAXIMUM EFFECTIVE spark advance (after deducting the knock retard) that I can run without causing "knock" to occur.
Sometimes it is better to back off the spark advance a bit and go for long term durability than trying to get an extra couple of HP and shorten your engine's life. Also, if the "consistency" of your gas is questionable, you may wish to consider that too. Where I live we get 94 Octance and the gas is very consistent, but I know that when I travel into the US that my car will ping like crazy @ WOT with 91.
Now, if I am planning a trip to the US, I will purposely burn another prom just to avoid this issue (lower quality gasoline). I accomplish this by using a "piggy-back" where the "piggy-back" has the slightly more aggressive spark advance and the Memcal will have the more conservative spark advance. Then, if I find I have to use a lower octane of gas or if I got a bad tank, I just disconnect the "piggy-back" and run off the more conservative Memcal.
I am debating about writing an "upshift retard routine" for my SD to see if I can get a few degrees more. But it really is showing that I have too much spark advance and my engine is telling me to "back it off" a bit.
What is your "effective" total spark advance right now? I am finding that with my stock L98 heads 28-29* is about the MAXIMUM EFFECTIVE spark advance (after deducting the knock retard) that I can run without causing "knock" to occur.
Sometimes it is better to back off the spark advance a bit and go for long term durability than trying to get an extra couple of HP and shorten your engine's life. Also, if the "consistency" of your gas is questionable, you may wish to consider that too. Where I live we get 94 Octance and the gas is very consistent, but I know that when I travel into the US that my car will ping like crazy @ WOT with 91.
Now, if I am planning a trip to the US, I will purposely burn another prom just to avoid this issue (lower quality gasoline). I accomplish this by using a "piggy-back" where the "piggy-back" has the slightly more aggressive spark advance and the Memcal will have the more conservative spark advance. Then, if I find I have to use a lower octane of gas or if I got a bad tank, I just disconnect the "piggy-back" and run off the more conservative Memcal.
12-14-2001, 07:49 PM
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<font face="Verdana, Arial" size="2">Originally posted by Glenn91L98GTA:
I have found from all of my "experimentation" with spark advance that the first place I seem to detect "knock" (when I just cross the line of too much spark advance) is during the upshift. Sounds like you are finding the same thing.
I am debating about writing an "upshift retard routine" for my SD to see if I can get a few degrees more. But it really is showing that I have too much spark advance and my engine is telling me to "back it off" a bit.
What is your "effective" total spark advance right now? I am finding that with my stock L98 heads 28-29* is about the MAXIMUM EFFECTIVE spark advance (after deducting the knock retard) that I can run without causing "knock" to occur.
Sometimes it is better to back off the spark advance a bit and go for long term durability than trying to get an extra couple of HP and shorten your engine's life. Also, if the "consistency" of your gas is questionable, you may wish to consider that too. Where I live we get 94 Octance and the gas is very consistent, but I know that when I travel into the US that my car will ping like crazy @ WOT with 91.
Now, if I am planning a trip to the US, I will purposely burn another prom just to avoid this issue (lower quality gasoline). I accomplish this by using a "piggy-back" where the "piggy-back" has the slightly more aggressive spark advance and the Memcal will have the more conservative spark advance. Then, if I find I have to use a lower octane of gas or if I got a bad tank, I just disconnect the "piggy-back" and run off the more conservative Memcal. </font>
I have found from all of my "experimentation" with spark advance that the first place I seem to detect "knock" (when I just cross the line of too much spark advance) is during the upshift. Sounds like you are finding the same thing.
I am debating about writing an "upshift retard routine" for my SD to see if I can get a few degrees more. But it really is showing that I have too much spark advance and my engine is telling me to "back it off" a bit.
What is your "effective" total spark advance right now? I am finding that with my stock L98 heads 28-29* is about the MAXIMUM EFFECTIVE spark advance (after deducting the knock retard) that I can run without causing "knock" to occur.
Sometimes it is better to back off the spark advance a bit and go for long term durability than trying to get an extra couple of HP and shorten your engine's life. Also, if the "consistency" of your gas is questionable, you may wish to consider that too. Where I live we get 94 Octance and the gas is very consistent, but I know that when I travel into the US that my car will ping like crazy @ WOT with 91.
Now, if I am planning a trip to the US, I will purposely burn another prom just to avoid this issue (lower quality gasoline). I accomplish this by using a "piggy-back" where the "piggy-back" has the slightly more aggressive spark advance and the Memcal will have the more conservative spark advance. Then, if I find I have to use a lower octane of gas or if I got a bad tank, I just disconnect the "piggy-back" and run off the more conservative Memcal. </font>
BKR as a function of VSS <g>
12-14-2001, 08:51 PM
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<font face="Verdana, Arial" size="2">Originally posted by Grumpy:
BKR as a function of VSS <g>
</font>
BKR as a function of VSS <g>
</font>
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