The solution for this issue is posted here Post number 53/54:
https://www.evolutionm.net/forums/ec...ng-issues.html

That doesn't work for me either because my load increases when the idle stumbles:

Attachment 313769

Longer log attached.

have you adjusted the biss screw? I had the same problem you had with my old 9 and I believe it was because of the cams.my friend had the same problem too and he had m2 also.i had to set my biss and idle up to get rid of the issue.it still came every once in a blue moon but I could not replicate it.

I use evoscan to go into SAS move and the idle stays at 1k, which is where it's supposed to be, so the BISS appears to be fine?

Is your idle set at 1k too? I used to have this problem on my first evo and I played with the iscv and the biss and most of the problems went away. I couldn't get it to stall on me anymore. It was very rare that it did stall out on me. I read an interesting post that someone said it had gotten worst since they installed an exedy twin. A friend of mine had the same problems and he had the same clutch and cams as I did. I'm now starting to think it was the clutch. The post some1 said today was it was because of a lighter flywheel than stock...

My friend tried putting back the stock intake too and the stalling still happened. It seems the post I linked should solve your problem...


What are your fuel trims? It looks like you are running very rich...

Yep, idle is set to 1k.

When it stumbles it goes very rich. Oddly enough, when I was in closed loop, when it stumbled it would go full lean, and now that I'm in open loop, it goes full rich.

Trims should be fine, they're within +/- 5%. Still on stock injectors.

i had the same problem

Had? How did you fix it?

Raptor what clutch and flywheel are you using

all stock.

Ill have to try this. Will it work for any injector or just for the injectors you specified?

Shouldn't matter what injectors you have.

How do you know if its set properly?

Same here:confused:

My log look just like yours 400-500rpm with 90s load and 5 degrees timing

Wizzo, to check the BISS, activate the Speed adjusting screw actuator in evoscan. This will lock the IAC at a given position and allow you to adjust the BISS to the correct idle speed. Turn the BISS counter-clockwise to increase the idle rpm, and vice versa.

That being said, I've had quite a big breakthrough this week regarding my idle problems. I had checked the BISS a number of times and it was idling at 1k rpm, which is the same as what I have set in the rom. I had opened up the BISS some more to try to combat the drop to 500rpm, but it wasn't helping. Then it hit me - before my rpm's drop to 500, they would surge to 1500. So I wondered if the BISS was getting the idle to 1500 because it was opened too much and then the ECU over-compensated with the IAC and brought the idle down to 500. So I started gradually closing the BISS, without activated the actuator, so that the ECU would adjust the IAC to keep the idle at 1k as the BISS was closed. I would close it around half a turn and try it out on a drive. Each time I closed it some more, the idle would surge less, and it would subsequently drop less. I've now got it to where it surges to 1100 and drops to around 900, then goes back up to 1000, which is much better than before. I'm still tweaking it, but it definitely seems like I'm the right path.

However, sometimes when I clutch in at low loads going uphill it will still drop to 500, however it recovers much quickly. I believe this may be a separate problem. Either way, it's still vastly improved compared to what it was before.

Now, if your idle doesn't surge to 1500 before dropping to 500, I would NOT try my trick of closing the BISS. I don't think it would work, and it may instead make it worse, as the IAC and BISS will be working against each other.

Ok I checked my biss with Evoscan and it was low. About 800rpm. My desired idle is set to 960 so I set the biss to 960. I'm assuming that is correct. If it is I was wondering if I set the biss higher than my desired idle will it idle at the biss setting or the desired set idle. I didn't have much time to play around with it so I didn't get time to test this. The reason I'm wondering is because now my idle is at 1100 rpm. So for now I dropped my steps at idle in the 170 and 180F cells. Now its idling at 960rpm. Not sure if that's the correct way to fix it but its works for now. My clutch in is a little better but is still trying to stall with clutch in after light load like when parking or stuck in traffic.