I'm sorry, I misspoke firstly. I have never had my car stall due to this issue. The lowest either of my evos have dipped to is about 200 rpm from the a/c clutch being engaged. Also, certainly it is a problem... however, the real question is not why not fix it but rather can we fix it?

As far as there being plenty of modified cars out there that don't have this issue, well I am sure that is true. There are plenty of stock and modified cars out there that do not have this issue. There also are plenty of stock and modified cars out there that do have this issue. Weather it is modified or not has very little to do with this, unless you're talking about modifications such as under drive pulleys or a/c removal.

Having thought about this problem in detail, there is truly no "fix" as far as I can tell. You can't reflash an ecu to shift profiles depending on weather or not the a/c clutch is engaged. Even if you could do this, essentially all you would be doing is giving it more gas, i.e. increasing the idle, to compensate for drag... that isn't fixing the problem but only fixing a symptom of the problem.

The actual problem is the load the a/c puts on the serpentine belt and therein the effect it has on any respective peripheral attached to said belt, including but not limited to the engine. So, if the a/c clutch being engaged is causing the engine to have too much of a load on it at idle, then the solution is to disengage the a/c clutch at idle.


Please, correct me if I am wrong.

 

When I say modified I mean 600hp EVO that doesn't stall with the A/C on.

I also wanted to make it clear that it's not at idle that I was having the problem, it's when decelerating then depressing the clutch from an engine speed of > 3000 RPM.

 

Right, so when the clutch is depressed from 3k rpms, give or take, it falls down toward idle... if the a/c were off it would fall down and hit idle... but since the a/c is creating too much of a drag on the entire system, it falls past idle and stalls or almost stalls. I'm curious exactly what you expect it to do? You know the problem, you know what is causing it... you know that there is no guaranteed fix for it... you know evos are not the only car with this problem... you also know that disengaging the a/c clutch would fix the problem for sure.

It is likely that a 600 whp evo won't do this because...
well, firstly, likely won't have a/c as far as history has taught me...
and, second, it has enough power to keep all peripherals on the serpentine belt moving without hesitation.

 

after reading some other posts i decided to remove the IACV from the TB for inspection. the end that moves in and out was a little dirty but looked ok, so i cleaned and applied some greese to make sure it was not sticking (very small amount) and reinstalled.

car started up idled just like before AC on and off no problem (not moving). went down the steet and tested with AC on and same result stall or idle bounce. not sure if i want to spend the money on a new IACV if i can't figure out if its mechanical or ecu related.

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Do you guys have stock injectors? If you do then N/M but if you don't then part of the issue when the car can't catch your idle is your injector scaling as well. Not only the BISS screw but your if your injectors are not scaled close and your latencies are off your car will not idle correctly or will not catch the idle on throttle blips. I had the same issue until I corrected my injector latencies and scalings.

 

I hate the way my car feels when i turn the A/C on. I try not to use it but is gets freakin hot out here in AZ

 

which way do you turn the BISS to increase idle? clockwise? counter-clockwise?

 

counter

 

my car does that occasionally but u can prevent it by reving alittle when coming to a rolling stop. i heard it has something to do with when you put a intake on, i also have cams which im sure doesn't help my idle

 

I run my AC basically 8 months of the year here and it does suck - one of the downsides of having such a small engine.

 

Mine to, i have a big decrease in power. It idles lowere when i come to a stop but doesnt go low enough that it may cut off.

 

Ouch, that's harsh...oh well Evo > STi any day. I remember Top Gear doing the comparison between the Evo and STi and in the end the Evo was dubbed as a "Man's car"

 

That’s funny cause they both stated they'd rather drive the STI around even though it was the "man's car".
Ok I see a couple issues being discussed here. One involves the car idle and the car is already stopped. The other is the stall issue when decelerating and the clutch is popped in. I just retuned an Evo 9 with Cossies M2's. the car idles just fine when its already stopped but dies on occasion when the clutch is popped in. has turning the BISS screw helped this particular case? I will try it on the car and will report back but are there any other suggestions for the 9's besides raising idle w/ac on via ecuflash which I have already done as well.

 

how to pull out the IDLE map?
i M just have my EVOSCAN 2.6 an hour ago.
first put in the cable?
second start the car?
third putting in into the SAS mode ?
then I don't know , could u help me out ? thanks

 

I've posted how to do this five times in this thread, please read above!!!!!