Yeah, the issue is that we arent logging the 'TARGET' DEMAND% like you mentioned and what we see is the corrected result of DEMAND%+DEMAND TRIM. Does anyone know the address to log the 'TARGET' DEMAND% ?

Its simple enough to just add DEMAND% and DEMAND TRIM to see what value it was intending to hit.

 

My guess is that adding 13 steps to your Initial steps value of 7 would yield a 0% DEMAND TRIM at operating temp.

 

I don't think I've mentionned that we are logging target demand. I wrote that we log "final demand" which is corrected demand+trims. I don't think we need to log anything else to progress in this.

 

Small tidbit I found when I logged ISC trims a couple of days ago: AC off trim was very close to zero, but the AC on trim was 12%. ISCV demand goes up by 12 when I turn AC on (from ~17 to ~29). I imagine the two are related. Now I need to figure out how to zero the AC trim.

 

Obviously yes, I'm at 14,5% warmed up demand and trims are at 5%.
14,5% is 37steps (lookup table)
14,5% - 5%trim is 9% is 25 steps (lookup table)
37-25=12steps. (to add to initial position)


I was just trying to understand how all that worked and react to different settings, before actually trying to adjust trims to zero.

 

Add 30 steps to your AC ON initial steps table.

 

Raptord, ^^ this is how you zero trims. With the lookup table.

 

^^ If we continue discussion/testing/progress some more we are on our way to resume all things in one main thread. It's pretty messed up here. Some good info is starting to be hidden. I have some time to write it and it would be very kind to have both your help and share all our findings.

 

Absolutely, I love that this thread's gotten very active all of a sudden with our testing. I think there's a lot of people that could benefit from the things yourself and Jamie are uncovering.

 

For now all the issues related to ISCV that we could call "understood", and solvable by tuning:

First thing to do before chasing a car's problem will be doing a boost leak test, BISS adjust, and all mechanical checkups.
-The cold start idle spike issue is solved. I pretty much have perfection everytime. (stepper maximum)
-Idle fluctuation: mainly caused by non linear initial steps vs coolant temp.
-Idle trims adjustement and different AC idle: I hope to hear some progress from you Raptord. We have some understanding about how the trims work thanks to Jamie@Dynotech tuning.
- The throttle hang issue was solved by the lowering RPM adder (others could chime on this)


If the tuner knows exactly how the system works and react, solving these problem will be much easier.
I'll let the discussion go further so we can confirm all what we're on.

 

So here is my thinking. We know the ECU references the IDLE STEPPER TABLE for its ISC step position. We also know that if we activate the BISS screw adjustment feature, it locks the ISC steps to only using the 'Initial ISC Step Postion-AC off' table.

My assumption was that meant that this table was sort of the 'BASE' setting and everything else built off of that parameter. I then started zero'ing out EVERY-SINGLE idle table to see if the ISC position would basically work its way back down towards the 'Initial ISC Step Position-AC off' value.

Well, that didnt happen at all. In fact, the car seems to still target roughly the same demand% area in the Idle Stepper Table no matter what I did. Something has to give it a Deamnd% initial target to shoot for.

Thoughts?

-Jamie

 

Yes it's like not all the demand% tables have been found. Obviously it takes much time and it's very complicated. Unfortunately I can't help for that dissasembly

For the rad fan kicking in, as you point by email, I also confirm that I have the 3% added demand, as in the log I sent you. It could be voltage related because some other accesories in the car also raise the demand%.

The current demand% tables seems to have little to no effect and what is odd is that some CTS adder table would add 50 to 100% demand in cold temps. When I zeroed them out, I still had the high demand spike on cold start. After the demand spike, the demand was where it always have been. My car was just not in these specific subroutines I guess.

There isn't much interest playing with majority of the known demand% tables because if the BISS, intial steps, trims, and stepper lookup are set properly, one's car will get a solid idle. I see the RPM hang issue that could use some demand table adjustment. Did you experience any other issue that would need adjusting some known demand% table?

 

So the proper way to adjust BISS would be:

-Make sure that initial steps table, operating temp are under 10 steps to give room to the demand% system
-Log Demand trim at operating temp idle.
-Go in SAS mode
-If trim is positive, open the BISS / If trim is negative, tighten the BISS
-Get out of SAS mode
-Wait 5minutes for the trim to readjust and stabilise
-Get back in SAS mode
-Repeat until trims are close to zero

After that, could follow a procedure to adjust cold coolant temp initial steps by trying to reach target idle at every coolant temp conditions, without any fluctuation.

Also, both the above procedures would be repeated with AC on.

 

I don't know if it has been proven somewhere, but I want to point how this table works:


This table is used by the system when the speed is over 0mph. This isn't viewable by logging steps because as we know we only log the demand lookup related steps. I have this table set higher than AC OFF Neutral. So if the car is rolling / not stopped, it idles higher than my target. As soon the speed reach 0mph, the idle quickly drops to his target. At even 2 or 3mph, the AC off Drive seems to be used.

So what I suggest is that AC off Drive, and Desired idle RPM Drive would be set a little bit higher than neutral, this allowing to slowdown the RPM drop and avoiding idle surge.

What is odd, is that on the IX 88590715 xml I have, what is defined for this is:
CTS Adder AC ON Drive (which is in fact initial steps)
and the Desired idle RPM Drive table isn't defined.

 

I had logged it to activate at around 5mph during coast down at one point back in the day. This is the table to adjust for stalling when coming to a stop.

-Jamie