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A/C Driving tuning w/HPT?

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Old Sep 20, 2005 | 08:24 AM
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Unhappy A/C Driving tuning w/HPT?

My car is SD tuned pretty good at the moment. But with it still being 90*+ down here I tried to use the A/C and it sticks at about 3500rpms(or more) when I push in the clutch. have to come to a full stop for the rpms to come down.

What do I do? I am a rookie at best and have no idea where to go from here to get the rpms to come down and drive normally. Could someone look at my bin and provide suggestions?

Thanks.
Jim
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Old Sep 20, 2005 | 08:47 AM
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HPTuners or LS1Edit or what software If you have HPTuners, send it

email your bin to fredsanford2003_AT_yahoo.com
ill look at it tonight

In the meantime, if you got time, there are settings all over the place for the AC. Look around in the editor.
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Old Sep 20, 2005 | 09:26 AM
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HPT (title).

I see all the settings just dont know how to make the rpms not stick while driving.
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Old Sep 21, 2005 | 01:29 PM
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Anyone else care to help?
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Old Sep 21, 2005 | 03:57 PM
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Get your RAF inline, and jack up your max a/c offset to like 3.00 or so.
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Old Sep 27, 2005 | 08:48 AM
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did you ever get this resolved?
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Old Sep 27, 2005 | 09:09 AM
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Originally Posted by GuitsBoy
Get your RAF inline, and jack up your max a/c offset to like 3.00 or so.
What does RAF stand for?
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Old Sep 27, 2005 | 09:09 AM
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Originally Posted by Steel Chicken
did you ever get this resolved?
Not yet...
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Old Sep 27, 2005 | 09:14 AM
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Originally Posted by Jimmyz
What does RAF stand for?
Running airflow.
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Old Sep 27, 2005 | 06:54 PM
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Check your IAC effective area when you log. You don't want your IAC counts to go much over the 130-150 area when cruising. If you're seeing counts in the 200-310 level, then you've found your problem. I had this same problem too.

You want your dynamic air to match your idle airflow at idle with and without the a/c running. This usually means a pretty steep ramp (15 count increase per cell) on the IAC counts, but once you get past the idle level with A/C on (let's say 90 counts just for grins), you'll want to flatten the curve to around 5 counts increase per additional cell. Try that and see if it helps any. It helped me.

Mine look like this:
starting at cell 22.0
1,3,8,15,30,45,60,76,92,100,105,110,115,120,125,13 0,135,140,145,148,151,155,161,165...(increasing all the way to 260). If they look strange it might be because I'm running a Nick Williams 90mm TB, but the principles are sound.

Hopefully, this will help.
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Old Sep 27, 2005 | 07:08 PM
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Originally Posted by Patrick G
Check your IAC effective area when you log. You don't want your IAC counts to go much over the 130-150 area when cruising. If you're seeing counts in the 200-310 level, then you've found your problem. I had this same problem too.

You want your dynamic air to match your idle airflow at idle with and without the a/c running. This usually means a pretty steep ramp (15 count increase per cell) on the IAC counts, but once you get past the idle level with A/C on (let's say 90 counts just for grins), you'll want to flatten the curve to around 5 counts increase per additional cell. Try that and see if it helps any. It helped me.

Mine look like this:
starting at cell 22.0
1,3,8,15,30,45,60,76,92,100,105,110,115,120,125,13 0,135,140,145,148,151,155,161,165...(increasing all the way to 260). If they look strange it might be because I'm running a Nick Williams 90mm TB, but the principles are sound.

Hopefully, this will help.

Thanks! I'll give this a try.

Jim
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Old Sep 28, 2005 | 01:11 PM
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Here's what mine look like 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 24 34 43 53 63 75 89 106 124 141 158 172 182 191 200 207 213 219 226 231 238 245 253 260 268 276 285 294 304 310 310 310 310 310 310 310 310 310 310 310 310 310 310 310 310 310

Idling the IAC count is up between 130-145. Idle Desired AF & Dynamic AF are off by about 2.5g/sec. w/the A/C on. A/C off I get none of these issues. Car drive pretty good for all the mods.

Last edited by Jimmyz; Sep 28, 2005 at 01:44 PM.
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Old Sep 28, 2005 | 08:10 PM
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Looks like your curve is way too steep after the A/C idle speed. You need to get your regular idle counts to around 30 and your counts with A/C on around 90 or under. Either crack your throttle blade or drill a hole in your TB. 130-145 is way too high IMO.
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Old Sep 28, 2005 | 08:45 PM
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Originally Posted by Patrick G
Looks like your curve is way too steep after the A/C idle speed. You need to get your regular idle counts to around 30 and your counts with A/C on around 90 or under. Either crack your throttle blade or drill a hole in your TB. 130-145 is way too high IMO.
I understand, just dont know how to do this w/HPT. Already have a hole on the
TB blade and the TB is at .59 cracked.
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Old Sep 28, 2005 | 08:57 PM
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Originally Posted by Patrick G
Looks like your curve is way too steep after the A/C idle speed. You need to get your regular idle counts to around 30 and your counts with A/C on around 90 or under. Either crack your throttle blade or drill a hole in your TB. 130-145 is way too high IMO.
the effective area table is dead on when the ac is off. i was the one that actually set the table up. i dont have ac on my car so i have no clue on adjustments for it.

jim i am looking at the log with the ac on and the airflow trims chagne a good bit with it on. it wants to pull out a lot of air, about 1 g/sec more than regular idle. the effective area can be tweaked more now that the ve was changed but it is only off by about a half a g/sec which it SHOULDNT make it that bad.

patrick, from a cold start the 2 airflow lines match each other very well, well they are slightly off now but before they were dead on. even with the ac on they match. what ac parameters can be changed? or what idle settings may be screwy. like i said, i have never tuned a cammed car with a/c since mine is gone so im lost. we tried some stuff but it didnt do ****
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Old Sep 28, 2005 | 09:11 PM
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ok here is what i am thinking. the ac offset for adaptive idle airflow was set to 3.00, when you get on the gas from a light it will remember this number as well as the stit and keep that as idle airflow. if the remebered values are faulty, which i have seen logging on my car when i step on the gas, then it would falsely say it needs xx amount of air added for idle giving him high rpms. sound like somehwere to look or no?
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Old Sep 28, 2005 | 09:14 PM
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Originally Posted by Jimmyz
My car is SD tuned pretty good at the moment. But with it still being 90*+ down here I tried to use the A/C and it sticks at about 3500rpms(or more) when I push in the clutch. have to come to a full stop for the rpms to come down.

What do I do? I am a rookie at best and have no idea where to go from here to get the rpms to come down and drive normally. Could someone look at my bin and provide suggestions?

Thanks.
Jim
Quick fix-> Idle Airflow tab -> "AC Offset Max - In Gear" -- AC offset airflow maximum limit, AC on and in gear.
Bump this value to 3.0-4.0 g/sec.

Ideal fix -> AC Compressor Torque The AC compressor places a large and variable load on the engine when engaged. The PCM has a complex model of AC Torque load including inertia effects and ramp in/out when the AC clutch first engages. The AC torque calculation is also used to calculate the Idle AC Airflow compensation for IAC/ETC control during idle.

Torque vs. AC Pressure: This is the torque loss of the AC compressor versus AC Pressure.
Torque vs. IAT: This is the increase in AC torque loss due to inlet air temperature.
Inertia Torque: This is the model of inertia torque load for the AC clutch when it engages.

These three tables need to be adjusted for increased TQ loss (need more airflow). You might try copying the tables from a Holden VY SS - just a guess though.
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Old Sep 28, 2005 | 09:15 PM
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i was just gonna ask about the ac torque. with underdrive pulley would that not need to be adjusted to compensate since the torque seen will be different?
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Old Sep 28, 2005 | 09:22 PM
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Originally Posted by Bink
Quick fix-> Idle Airflow tab -> "AC Offset Max - In Gear" -- AC offset airflow maximum limit, AC on and in gear.
Bump this value to 3.0-4.0 g/sec.

Ideal fix -> AC Compressor Torque The AC compressor places a large and variable load on the engine when engaged. The PCM has a complex model of AC Torque load including inertia effects and ramp in/out when the AC clutch first engages. The AC torque calculation is also used to calculate the Idle AC Airflow compensation for IAC/ETC control during idle.

Torque vs. AC Pressure: This is the torque loss of the AC compressor versus AC Pressure.
Torque vs. IAT: This is the increase in AC torque loss due to inlet air temperature.
Inertia Torque: This is the model of inertia torque load for the AC clutch when it engages.

These three tables need to be adjusted for increased TQ loss (need more airflow). You might try copying the tables from a Holden VY SS - just a guess though.
if the rpms hang that means its getting too much air. plus the idle air trims go negative by a g/sec with the ac on .
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Old Sep 28, 2005 | 10:32 PM
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Originally Posted by WS6FirebirdTA00
if the rpms hang that means its getting too much air. plus the idle air trims go negative by a g/sec with the ac on .
Oh...my bad ...sorry. Use the "AC Offset Min - In Gear" - add 1.0-1.5 g/sec. It will "Learn" the correct offset value.

My understanding is the Ramp in and Ramp out rates as well as the A/C torque tables will need refinement. You can scan the A/C pressures.

You might try reducing the A/C Ramp In (and Ramp Out) by 1.00 g/sec across the board.
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