been playing around with the car, adding timing. Whats a safe level for correction factor?
09-02-2006, 09:07 PM
#11
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I've seen cars pegged at 15 (how did you see 16?) for an extended period of time, no problem.
For a long time, people didn't really care about CFs and watched KVs.
Many homebrew guys have run or still run XR on pump gas with little or no timing adjustment. A majority of those cars have very high CFs.
So you're saying there is only 1 timing map? Seems to me that many would disagree with that. I don't have proof one way or another.
Many homebrew guys have run or still run XR on pump gas with little or no timing adjustment. A majority of those cars have very high CFs.
So you're saying there is only 1 timing map? Seems to me that many would disagree with that. I don't have proof one way or another.
09-02-2006, 09:12 PM
#12
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B5QShip was watching, so all was well =p
Nah, his car is running pretty well for APR now. 5.3 FATS for 1.1 bar max boost in 75F is pretty solid, imo. 15 - 20 deg timing at 6.5 - 7k RPMs and 0.86-ish O2s. Much better than before. Car really feels strong and smooth now.
I think we both learned some things today, so all in all a productive day....save for my pos s4.
I think we both learned some things today, so all in all a productive day....save for my pos s4.
09-02-2006, 09:12 PM
#13
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I'd be interested to see where 16 was seen. I can't remember the source offhand
but either the ME7 or some other official Audi documentation stated that the ECU could not see/pull past 15 degrees.
09-02-2006, 09:28 PM
#16
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It will not switch to another timing map because of knock sensor activity.
Yes, I've seen 16. There are a googleplex timing maps, but you won't get another one based on knock sensor feedback alone. If the software is pulling as much timing as it can (pegged) then the knock sensor activity is beyond the ecu's ability to retard timing enough to stop the perceived knock. That does not mean your engine will esplode because of knock.
To suggest that the ecu could go beyond the simple timing retard correction factor is to imply that it has the ability to autotune the ignition curve. Were that the case we wouldn't need software tuners anymore. Lemmiwinks, a boost controller and stout K03 software would be all we needed for any cylinder pressure, octane and temps.
To suggest that the ecu could go beyond the simple timing retard correction factor is to imply that it has the ability to autotune the ignition curve. Were that the case we wouldn't need software tuners anymore. Lemmiwinks, a boost controller and stout K03 software would be all we needed for any cylinder pressure, octane and temps.
09-02-2006, 09:38 PM
#17
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We were using VAG-COM to log 3 blocks at a time because we made so many changes
and didn't want to do a gazillion runs, so the sampling rate was pitifully slow - something like 1Hz. It was pretty difficult to make comparisons between runs because of this (lack of data & statistical uncertainty/error in FATS calculations), but overall we learned the following:
CFs for stock APR software (v5.0 w/ K04s & Piggie Pipes) were basically zero. O2s for stock APR software were around 0.885 near redline.
Pulling 5% primary fuel pushed O2s closer to 0.865, gave statistically significant power increases (FATS), and drove CFs up several degrees. Adding 4.5 degrees of timing advance also gave statistically significant power increases, drove CFs up several degrees, and increased the timing advance curve several degrees. These two changes yielded 0.865 O2s at redline, 18 deg or so of timing advance at 6.5k - 7k RPMS, CFs of 7-9, and a 0.2s FATS improvement. Changing the MBC in parallel from ~16psi to ~17.5psi shifted the boost curve up very slightly in the midrange and gave 0.1 - 0.2s improvement in FATS times.
While these tweaks seemed perfectly safe, we decided to set primary at -4% and timing at +3.75 to keep CFs <10 in the worst of conditions and because -5% fuel just seemed like a lot. Farbs went from 5.7s FATS to 5.3s FATs in similar conditions (5 deg cooler today) with these tweaks. However, the best lesson to be learned today is that VAG-COM sucks and ECUx is a necessity for tweakers.
CFs for stock APR software (v5.0 w/ K04s & Piggie Pipes) were basically zero. O2s for stock APR software were around 0.885 near redline.
Pulling 5% primary fuel pushed O2s closer to 0.865, gave statistically significant power increases (FATS), and drove CFs up several degrees. Adding 4.5 degrees of timing advance also gave statistically significant power increases, drove CFs up several degrees, and increased the timing advance curve several degrees. These two changes yielded 0.865 O2s at redline, 18 deg or so of timing advance at 6.5k - 7k RPMS, CFs of 7-9, and a 0.2s FATS improvement. Changing the MBC in parallel from ~16psi to ~17.5psi shifted the boost curve up very slightly in the midrange and gave 0.1 - 0.2s improvement in FATS times.
While these tweaks seemed perfectly safe, we decided to set primary at -4% and timing at +3.75 to keep CFs <10 in the worst of conditions and because -5% fuel just seemed like a lot. Farbs went from 5.7s FATS to 5.3s FATs in similar conditions (5 deg cooler today) with these tweaks. However, the best lesson to be learned today is that VAG-COM sucks and ECUx is a necessity for tweakers.
09-02-2006, 09:42 PM
#18
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Just curious - how do you arrive at that threshold? Is it...
because that's the highest before the car becomes slower or is that what stock programming runs or is it based on something else? Just curious. I know this is what the board has come to accept but it seems rather arbitrary unless I missed something. TIA.
09-02-2006, 09:43 PM
#19
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Do you have any documentation to support this (timing map won't change due to knock activity)?
You've got my attention. I'd love to see that.
Again, how did you see 16 degrees of correction? I've logged tons of cars with both VAG and ECUx, neither have gone above 15 and some cars have been pegged at 15 for almost the entire RPM range.
My understanding thus far has been the ECU can and will protect itself by further reducing timing once the maximum correction of 15 degrees has bene reached. I've been told this by people most definitely smarter than myself. I forget if they said it was by jumping to another map or what, but it was definitely made clear to me that this was possible.
I don't see how the above would "imply that it has the ability to autotune the ignition curve." I simply see it as an additional built-in safety net. I would NOT assume that because it can pull back timing in extreme conditions that it would also advance timing when it saw the opportunity.
Please teach me.
Again, how did you see 16 degrees of correction? I've logged tons of cars with both VAG and ECUx, neither have gone above 15 and some cars have been pegged at 15 for almost the entire RPM range.
My understanding thus far has been the ECU can and will protect itself by further reducing timing once the maximum correction of 15 degrees has bene reached. I've been told this by people most definitely smarter than myself. I forget if they said it was by jumping to another map or what, but it was definitely made clear to me that this was possible.
I don't see how the above would "imply that it has the ability to autotune the ignition curve." I simply see it as an additional built-in safety net. I would NOT assume that because it can pull back timing in extreme conditions that it would also advance timing when it saw the opportunity.
Please teach me.