Legnum Boy
18-01-2005, 12:45 AM
I have a few thoughts regarding the thread title. :| (If you bore easily, don't read on ;) )
The first and most obvious issue I dreamed up was the throttle position during gearchange. The butterfly remains fully open during the change up, thus meaning the boost is not dumped. All of a sudden, the engine reduces its need for the air being forced in and hence the boost spikes.
My AVCR can handle this quite well. A stable 0.9 Bar boost will generate a 1.05 Bar spike at gearchange, but only for a fraction of a second. The stock solenoid would boost a stable 0.5 Bar with a spike upto nearly 1 Bar at change up.
The second issue is a bit more problematic, although probably not exclusive to autoboxes, and I would love to know if anyone has worked a way round it, without the need to drastically reduce the stable boost level or remove/raise fuel cut.
When cruising in higher gears (4/5) on motorways or similar, 2500/3000 revs at negative boost, I then apply a reasonable amount of throttle, but not enough to enduce kickdown/or am in tiptronic mode. Because the turbo's are already spooled, the boost comes on at massive pace, and far exceeds the normal stable level. ie. stable level = 0.9 Bar - Boost surge can = 1.4 Bar and in most circumstances fuel cut.
The AVCR has all sorts of different level settings, rev specific boost adjustment, gear specific boost levels (Check the third issue for more on that), self adjusting feedback etc. etc. but after countless hours of switching things on/off up/down, I cannot change this annoying trait. I just have to be aware of how quickly I apply the throttle in those situations, which is severely damaging my playtime antics. :sad3: :sad3: :sad3:
The final issue, and this applies only to the AVCR used in conjunction with an Auto/Tiptronic gearbox, is the gear specific boost levels (aka Gear Start Duty +/-).
My beef with this is, the AVCR has to know which gear you are driving in for it to apply the correct settings you have requested. It does this by monitoring the ecu speed signal, in conjunction with the ecu rev signal. This, on a manual car is a surefire way to know which gear you are in. What happens with the autobox though.... the torque converter allows quite a large amount of variance of engine revs within gears. So much, infact, that when you apply enough throttle to raise revs without the gears actually changing down, the AVCR thinks you have downchanged, and so adjusts the boost to the level you requested for the gear below, which you actually haven't changed down to.
I am aware that the gear recognition setting can be altered +/- to allow for different ratios, but it is an absolute figure, that does not emcompass the variance of revs the torque converter allows. :rolleyes5
Quite soon, I will be taking my car for a good few hours RR set up, just to see if the guys there can reduce or eliminate any of the above problems, and I will also then know for sure how badly I am over/under fuelling (for peace of mind, or not...)
If they confirm the above and the AVCR is better suited to a manual car, I will have no choice but to sell it, and purchase a nice simple Greddy B that will still give me the neccesary boost increase, and boost gauge functions, but will also allow me to control a maximum safe limit, somewhere this side of the fuel cut. Something that the AVCR does not provide and is sorely lacking IMHO.
If anyone has stuck with it and read this yawning monstrosity, Thank You and all feedback is greatly welcomed.... :-D
The first and most obvious issue I dreamed up was the throttle position during gearchange. The butterfly remains fully open during the change up, thus meaning the boost is not dumped. All of a sudden, the engine reduces its need for the air being forced in and hence the boost spikes.
My AVCR can handle this quite well. A stable 0.9 Bar boost will generate a 1.05 Bar spike at gearchange, but only for a fraction of a second. The stock solenoid would boost a stable 0.5 Bar with a spike upto nearly 1 Bar at change up.
The second issue is a bit more problematic, although probably not exclusive to autoboxes, and I would love to know if anyone has worked a way round it, without the need to drastically reduce the stable boost level or remove/raise fuel cut.
When cruising in higher gears (4/5) on motorways or similar, 2500/3000 revs at negative boost, I then apply a reasonable amount of throttle, but not enough to enduce kickdown/or am in tiptronic mode. Because the turbo's are already spooled, the boost comes on at massive pace, and far exceeds the normal stable level. ie. stable level = 0.9 Bar - Boost surge can = 1.4 Bar and in most circumstances fuel cut.
The AVCR has all sorts of different level settings, rev specific boost adjustment, gear specific boost levels (Check the third issue for more on that), self adjusting feedback etc. etc. but after countless hours of switching things on/off up/down, I cannot change this annoying trait. I just have to be aware of how quickly I apply the throttle in those situations, which is severely damaging my playtime antics. :sad3: :sad3: :sad3:
The final issue, and this applies only to the AVCR used in conjunction with an Auto/Tiptronic gearbox, is the gear specific boost levels (aka Gear Start Duty +/-).
My beef with this is, the AVCR has to know which gear you are driving in for it to apply the correct settings you have requested. It does this by monitoring the ecu speed signal, in conjunction with the ecu rev signal. This, on a manual car is a surefire way to know which gear you are in. What happens with the autobox though.... the torque converter allows quite a large amount of variance of engine revs within gears. So much, infact, that when you apply enough throttle to raise revs without the gears actually changing down, the AVCR thinks you have downchanged, and so adjusts the boost to the level you requested for the gear below, which you actually haven't changed down to.
I am aware that the gear recognition setting can be altered +/- to allow for different ratios, but it is an absolute figure, that does not emcompass the variance of revs the torque converter allows. :rolleyes5
Quite soon, I will be taking my car for a good few hours RR set up, just to see if the guys there can reduce or eliminate any of the above problems, and I will also then know for sure how badly I am over/under fuelling (for peace of mind, or not...)
If they confirm the above and the AVCR is better suited to a manual car, I will have no choice but to sell it, and purchase a nice simple Greddy B that will still give me the neccesary boost increase, and boost gauge functions, but will also allow me to control a maximum safe limit, somewhere this side of the fuel cut. Something that the AVCR does not provide and is sorely lacking IMHO.
If anyone has stuck with it and read this yawning monstrosity, Thank You and all feedback is greatly welcomed.... :-D