A/C Idle tuning
07-07-2007, 08:01 AM
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A/C Idle tuning I'm using HP Tuners and I have my idle pretty well tuned with ac off, no surging or searching. When I turn the ac on the car starts surging and the idle gets erratic but once I turn ac off all is good.
Where should I start making changes to compensate for the ac being on?
Where should I start making changes to compensate for the ac being on?
07-07-2007, 09:20 AM
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Is your problem that the A/C is constantly cycling and the
control loop just can't stay with it? Mine does that a lot
at idle and low cruise after the cam. I've been told there
is a RPM stability criterion that will cut A/C if it's not
smooth enough. Part of that smoothness problem may be
the A/C drag itself, or how that bothers the torque demand
- airflow model (which is guaranteed to be whacked once
you mod it enough to need VE table fiddling).
I've seen the A/C torque table really affect "cruise control"
and idle stability on my and another guy's car. The thing is
every time I try to change it things get worse in some other
way (fix "cruise control", then it dies etc.).
Thinking seriously about killing the adaptive idle altogether
and running straight airflow / IAC and take whatever the
RPM turns out to be....
control loop just can't stay with it? Mine does that a lot
at idle and low cruise after the cam. I've been told there
is a RPM stability criterion that will cut A/C if it's not
smooth enough. Part of that smoothness problem may be
the A/C drag itself, or how that bothers the torque demand
- airflow model (which is guaranteed to be whacked once
you mod it enough to need VE table fiddling).
I've seen the A/C torque table really affect "cruise control"
and idle stability on my and another guy's car. The thing is
every time I try to change it things get worse in some other
way (fix "cruise control", then it dies etc.).
Thinking seriously about killing the adaptive idle altogether
and running straight airflow / IAC and take whatever the
RPM turns out to be....
07-07-2007, 11:02 AM
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Originally Posted by RedHardSupra
RAF for ACon table
Where is this "RAF for AC on table"?? The only thing I can find is AC offset max and mine is set to 3.0. When I log Ac air and I turn the ac on it goes right to 4.4 g/sec than stabilizes at like 3.6 g/sec. Where is all the extra air coming from if I have my ac offset max set to 3.0g/sec??
not trying to hi jack, just thought my question might help out both of us!
07-07-2007, 11:26 AM
#5
oops, that's what i get for posting when i'm sleepy 
idle rpm table has Gear vs PN and ACon vs ACoff tables. RAF table is only Gear vs PN.
i guess you gotta figure out how much more/less idle airflow you get with AC on, and then just figure out what RPM does it need to provide it, then set the ACon idle rpm to that value.
but that's theory, i havent had AC in 2yrs
idle rpm table has Gear vs PN and ACon vs ACoff tables. RAF table is only Gear vs PN.
i guess you gotta figure out how much more/less idle airflow you get with AC on, and then just figure out what RPM does it need to provide it, then set the ACon idle rpm to that value.
but that's theory, i havent had AC in 2yrs
