Will do. I already added all of the 1D's from that subroutine to my maps but have not played with them all yet. Initially when I saw that 1750 and 1752 were both defaulted at 8, I figured one would be an advance limit and one a retard limit. Changing 1752 had no effect that I saw, but 1750 was obvious what it did.

I noted 175c is tied to Target Idle with a default value of 240. It may be an rpm from target limit for the sensitivity.

I just saw the addresses are the same for 98640014, 94170014, 90550001 and 96530006, so if anyone else wants to play with it.

 

The exact formula is:

DeltaTiming = x/64*(y/500*TargetIdle - 0.256*CurrentEngineSpeed).

or

DeltaTiming = x/64*(0.256*SnapShotEngineSpeed - 0.256*CurrentEngineSpeed)

x = the 1D value at 0x174e
y = the 1D value at 0x175c

Engine speed is in RPM for the formulas as posted here.

The use of 0x1750 and 0x1752 is not for pos/neg values as the algorithm checks for pos/neg and does the math so that the outcome is always positive. In your ROM there is a flag that chooses between using the value at 0x1750 and 0x1752. My ROM doesn't have two values to choose from, so I can't easily figure out what conditions trigger the use of one value or the other in your ROM unless I spend a lot of time with it.

 

What exactly is the point of these definitions and what symptoms would you be able to fix? How would you be able to fix whatever these symptoms are(which maps do you adjust and which way do you adjust them)?

 

The function is for Idle Stability. Its purpose is to very quickly control your idle. So if you have big cams and the idle bops around, this can help to stabilise it. Normal idle control is slower to respond and works on a larger rpm error from what you really want. This works on a much smaller level and instantly adds or subtract torque at idle. Usually these functions are left for the more experienced tuner to setup.

Mr Fred, I had a play with 175c and it had no effect that I could see. I only spent around 10 minutes so maybe with some more time I can find its exact real-world function. I tried at 255, 32, and 0 with no obvious change. I might have a play with 1752 tomorrow again. It may be for either for A/C on or for In Gear. Considering all of the other Evo 7 and 8 roms I could find use the same addresses I would more expect it to not be related to the gear. I did all of my initial testing in Neutral with no A/C so that the timing was more stable in the map around 5 degrees. I might flatten the map and try again.

If anyone wants to add these addresses, add the following to your xml:

<table name="Idle Stability Timing Control" category="Timing" address="174e" type="2D" level="2" scaling="uint16">
<table name="Settings" type="Static X Axis" elements="3">
<data>Sensitivity</data>
<data>Timing Limit</data>
<data>Untested</data>
</table>
</table>

 

Would these tables be able to help with cold start idle fluctuation? My car upon cold start up will idle perfect at 15-1600 for 20 seconds and then it wants to die out and will die out if I don't give it a blip of throttle. I will have to blip the throttle for about 7 or so times within that time period. That symptom only happens for about a minute and then it stabilizes again. My fuel trims are just fine for idle, cruise, and long term (3%+-1 across the board).

 

No effect of 0x175c means that the SnapShotIdle is being used instead of TargetIdle. That's a bit surprising. I'll have to look at the origin of the SnapShotIdle more carefully.

I'll bet 0x1750 and 0x1752 are for neutral / drive.

 

No this wont fix anything major like wanting to stall. It is only there for smoothness.


Mr Fred, come to think of it, you can see the idle stability working even when you aren't near target idle, so it must primarily use the snapshot rpm. Maybe it has a gain of some sort based on how far you are from target idle as well?

 

Sorry for being off topic but do you have any ideas on my issue?

 

Stalling is usually when lean. Watch it with a wideband.

 

i tried adding this to my .xml tonight (88590015) and I get "..." in the right side of the table... The other 3 tables came out fine. I have double checked it twice, now and same result.

<table name="IAT-Compensated Ignition Trim" category="Timing" address="3c8e" type="2D" level="1" scaling="TimingTrim8">
<table name="MAF Air Temp" address="714a" type="Y Axis" elements="8" scaling="Temp"/>
</table>

 

If you use the new xml files that you just downloaded, this definition will work fine.

 

OIC I just added the definition from this thread to "MY" .xml file. I will try the entire new .xml file you have provided, and just add all of the map sensor stuff, etc.

 

Bump for 94170015 addresses

 

I'll give these a try in the next few days. I noticed when put my car in open loop mode with FAA bit 4, the car would idle surge at times when it has never surged before. I'll see if I can tune it out with these tables.

 

Might this Idle stability controll affect big cam users and how the car will rich stall at a stop light?

From what I read I believe if I up the sensitivity is should control the idle better (faster)???