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A/C makes car almost stall sometimes

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Old Jun 5, 2009, 01:24 PM
  #31  
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I have had idle issues as well. I had my car professionaly flashed and reflashed and I still had some stalling issues with AC on.

You can try to adjust the idle on the ECU via ECUFlash or adjust the idle screw as others have mentioned. I still had intermittent issues even after this, but a few low throttle tweaks to my SAFC II seems to have resolved it for me.
Old Jun 5, 2009, 02:24 PM
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Originally Posted by SmikeEvo
There is a idle control bleeder on the back side of the throttle body. Using a short philips screw driver slowly tune it with the a/c on and off to the point that the RPMs do not suffer too much with the a/c on.
That is fine but will mess with your stepper motor and it will eventually put the idle back to where it was. The correct way is to "sync" the ECU with the mechanical idle control screw. This is done by putting the ECU into SAS mode in EVOScan, which holds the ICS valve at a constant position. Then you adjust your idle to 800 + or - 50 RPM.

This will "sync" the ECU with the car so that when it says (for example) 50 ICS steps is 900 RPM, the car runs 900 RPM not 1100 or something other than that.

If you do not adjust it this way and do it without putting the car into SAS mode the car then has to adjust the ICS steps to get it to idle at 900 and will eventually go out of range and not be able to adjust enough.

Did I explain that enough?

Last edited by phenem; Jun 5, 2009 at 02:29 PM.
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Old Jun 6, 2009, 05:53 PM
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possibly some vacuum leak? My idle goes up when I turn my a/c on.
Old Jun 6, 2009, 06:00 PM
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A.C is good and sucks at the same time. :x
But i would just basically turn it on only freeways and streets/side streets, i would not turn that thing on, ha......just put the windows down.... WEE!!!!!
Old Jun 6, 2009, 06:05 PM
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Originally Posted by TheBigLubinsky
My a/c blows cold as hell, but the occasional stalling really sucks the big hole. I have a custom dynoflash. Would that have anything to do with it?
Your ECU needs adjustments to compensate for the additional load the A/C compressor puts on the car.

Last I checked the Dynoflash account was banned from Evom.

If you are interested in having us fix this for you, send us a PM.
Old Jun 6, 2009, 11:28 PM
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If you're getting tuned, especially with cams, your tuner should also tune the idle while the AC is on.
Old Jun 25, 2009, 01:31 PM
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Originally Posted by phenem
That is fine but will mess with your stepper motor and it will eventually put the idle back to where it was. The correct way is to "sync" the ECU with the mechanical idle control screw. This is done by putting the ECU into SAS mode in EVOScan, which holds the ICS valve at a constant position. Then you adjust your idle to 800 + or - 50 RPM.

This will "sync" the ECU with the car so that when it says (for example) 50 ICS steps is 900 RPM, the car runs 900 RPM not 1100 or something other than that.

If you do not adjust it this way and do it without putting the car into SAS mode the car then has to adjust the ICS steps to get it to idle at 900 and will eventually go out of range and not be able to adjust enough.

Did I explain that enough?
i am working on my idle, evo9 cosworth 272 cams...stalling issues with ac on when you press the clutch in while turning or sometimes just stoping. when i turn on SAS mode with the ac on idle drops to like 300-400 almost dies...i then adjusted it to 850 rpm. now when the ac is off idle is like 2000rpm.... what is the procedure for adjusting biss screw with sas enabled for AC on and then AC off.

tks
Old Jun 25, 2009, 01:47 PM
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Originally Posted by my04s2k
i am working on my idle, evo9 cosworth 272 cams...stalling issues with ac on when you press the clutch in while turning or sometimes just stoping. when i turn on SAS mode with the ac on idle drops to like 300-400 almost dies...i then adjusted it to 850 rpm. now when the ac is off idle is like 2000rpm.... what is the procedure for adjusting biss screw with sas enabled for AC on and then AC off.

tks
Do not worry about your A/C. You need to get your car to idle correctly first. First warm the car up to operating temperature. Once up to temp put the car into SAS mode, set idle to 800 + or - 50 RPM. Once set take vehicle out of SAS mode and let the idle come down (takes about 5-10 minutes). Once the idle settles you should be good to go. I bumped my idle while A/C on to 1100 RPM in my ROM so that it steps the idle up instead of leaving it the same RPM.
Old Jun 25, 2009, 02:08 PM
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ok, tks

the only table i have in my rom for a AC idle condition is Desired ISCV intial step position with AC on-neutral. the other two are AC off neutral and AC off drive. rom 88590013.

tables att left to right- ISCV with AC off Neutral, ISCV with AC off Drive, ISCV with AC on Neutral, Idle RPM neutral, Idle RPM drive.

Last edited by my04s2k; Jun 12, 2010 at 09:33 AM.
Old Jun 26, 2009, 07:07 AM
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update- car idles perfect when stopping or just sitting AC off.

with AC on it still can't catch the idle when coming to a stop sometime stalls or it bounces and stays on.

any ideas?

c
Old Jun 28, 2009, 01:35 PM
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sorry guys (phenem and my04s2k), please explain the procedure to adjust the idle.

attached is an image of the tables from ECUflash.
i just got evoscan and am not sure how to use it yet. i see an option for putting the ecu into SAS mode.

please list the procedures step by step if you can

thanks guys!
Attached Thumbnails A/C makes car almost stall sometimes-ac_rpm_initial.jpg  
Old Jun 28, 2009, 07:48 PM
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Originally Posted by TommiM
possibly some vacuum leak? My idle goes up when I turn my a/c on.
same for me
Old Jun 28, 2009, 08:45 PM
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OK guys,

First off you have to fix your idle to do this you have to do the following:

First warm the car up to operating temperature. Once up to temp put the car into SAS mode (in EVOScan down at the bottom right), set idle to 800 + or - 50 RPM by adjusting the BISS screw on the throttle body (screw right on the top of the TB just use a regular screwdriver to adjust). Make sure you get your idle to settle right around 800. Once set take vehicle out of SAS mode (uncheck EVOScan button) and let the idle come down (takes about 5-10 minutes). Once the idle settles you should be good to go and your idle is "synced" with your computer.

Once you get your idle working you have to bump up your idle in EVOScan. I attached the three maps you need to edit. I adjusted my idle to right around 1000 RPM and 1100 RPM with A/C on. You guys do whatever you need for your car to idle smooth.

YOU DO NOT NEED TO TOUCH THE ISCV INITIAL STEPS MAPS AT ALL THAT WILL JUST MAKE THINGS WORSE!

Hope that helps, sorry for the long time to reply. I have been busy working on v7 with Tephra.

~Zach
Attached Thumbnails A/C makes car almost stall sometimes-ss01.jpg  

Last edited by phenem; Jun 28, 2009 at 08:48 PM.
Old Jun 29, 2009, 12:26 AM
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excellent, thank you Zach.
did exactly as you said....will drive for a few days and report back.

thank you.
Old Jun 30, 2009, 04:26 AM
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Originally Posted by phenem
OK guys,

First off you have to fix your idle to do this you have to do the following:

First warm the car up to operating temperature. Once up to temp put the car into SAS mode (in EVOScan down at the bottom right), set idle to 800 + or - 50 RPM by adjusting the BISS screw on the throttle body (screw right on the top of the TB just use a regular screwdriver to adjust). Make sure you get your idle to settle right around 800. Once set take vehicle out of SAS mode (uncheck EVOScan button) and let the idle come down (takes about 5-10 minutes). Once the idle settles you should be good to go and your idle is "synced" with your computer.

Once you get your idle working you have to bump up your idle in EVOScan. I attached the three maps you need to edit. I adjusted my idle to right around 1000 RPM and 1100 RPM with A/C on. You guys do whatever you need for your car to idle smooth.

YOU DO NOT NEED TO TOUCH THE ISCV INITIAL STEPS MAPS AT ALL THAT WILL JUST MAKE THINGS WORSE!

Hope that helps, sorry for the long time to reply. I have been busy working on v7 with Tephra.

~Zach
thanks again for the help.

my idle is great with the AC off, but with ac on still does the drop and stall. i need to find out what other tables are needed on a evo9 for ac on conditions that work.

c


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