Ok im lost here. I have tried absolutely everything. My car simply will not come to a stop without stalling or bouncing. When it is sitting at idle, it idles great, no issues. But coming to a stop it will drop to about 400 and then raise to about 1100 and then bounce, other times it just doesnt even try to catch, just drops straight to 0.

I know that this topic has been covered before, but i dont thinks its completely clear. Everyone just says to raise the iscv steps at idle with ac on. Well ive gone all the way up to 90 steps, and it makes no difference.

I swapped to a new IAC today. On the first start it wanted to idle at 1800 rpm. I disconnected the battery and let it sit for 5 minutes, then plugged it back up and idled it for 10 minutes with ac off. Rpms came back down to 1000 and it was great. Tested it on the street with AC on, and omg, it was flawless, it dropped to 1000 and stayed put. drove around for a while more and it eventually started to drop to 500 or so, i raised the iscv steps some, and no difference, just made it bounce like it used to.

Do i need to be unplugging the battery every time i add more steps? or let it idle for a long time every time i add steps? Its just not making sense.

Evo ix on SD V7

Any advice guys, this is driving me flat out insane.

 

You have a lot of reading to do on IAC dissassembely, setting BISS in SAS mode and finally ramping up timing in the idle cells increasing timing as RPM falls to aid recovery. Unfortunately the ISCV system is not well defined or even unerstood in terms of all the flags conditions and trims involved. It can be improved but i have yet to see a difinative fix.

 

Try upping the values in the two BFPW tables by about 10-20%.

 

I set the biss using SAS mode, and the timing is ramped up to recover.

 

Have you replaced your throttle body seals?

 

Yea, TB seals are fine and there are no leaks. Pressure tested it.

 

Log ISC steps at Idle and report back...

 

It's not you, it's the ROM and tuned Evo's. It's a combination of MAF/Injectors that causes your car to stall. https://www.evolutionm.net/forums/ec...ing-issue.html

That thread explains the issue perfectly, and if you log your car, that's what's happening. People on here will tell you to play with ISCV values (most of which are poorly defined), adjust your BISS, set SAS mode, play with MAF comp tables, switch out to stock intake, etc, etc, etc. I changed every single part that has anything to do with idle on my car, and all the ROM changes that I could find, and it still stumbles.

Most of the ECU gurus on here have no interest in disassembling the idle, because for some reason or another, it doesn't happen on their Evo's. I'm sure if it did, there would probably be a solution right now.

The bottom line is the only thing that will fix your idle stumble is SD. But then there's other drivability issues that come with SD. 6 one way, half a dozen the other. You could go stand alone or return the car to stock. I'd like to have my cake and eat it too, but it looks like I'm going to have to go SD to get my car to stop stumbling. If you search on here you will find hundreds of threads on the issue, and none of them have a happy ending that works for everyone.

 

i had this problem very good advice

 

He is on SD now.


That's a whole lot of timing at idle. What load and rpm is your car at idle?

-Jamie

 

I'm having the same issue in mine. Trying to work it out but I'm still a noob at this stuff. Thread subscribed!

 

i've got the idle/iscv routines about 90% diassembled, maybe more. all the applicable tables are definitely out there. i think what's missing is a full understanding of what all the tables do. people continue to fiddle with the iscv steps table when it is the iscv demand that more likely needs tweaking.

one of my customers is having this issue, so i will be putting more time into it.

to the op: i recommend that you start logging iscv demand. its at MUT 76 in EvoScan. Use a scaling of 100*x/255. post up a logs of a dip and a stall. also, is your clutch switch working (e.g., is your two-step working)?

 

Let me know if I can be of any help with logging/revisions/updates. I've got an 03 running 94170015 V7 MAF. Jay@Boosted is doing the tuning, and he's got a bunch of my stumble logs as well.

On another note, the HKS turbo I bought from you was good for +30/30 over my old TME turbo on 91 octane. Weather was >20F hotter on HKS turbo as well. Starting on e85 tune now...

If you can figure out how to get the idle to stop stumbling I'd be more than happy to send you $$$ for the cause!