OK,

This is a new thread to discuss the issues with throttle hang on the 96530706 ROM when switching over from a 9417 USDM ROM.

Some notes from the other thread were:

I agree I think it has something to do with fuel cut on decel, not ISC stepper settings. It seems to be dumping fuel in on decel but I have not logged the ISC stepper value to confirm that idea.

They have the same axis but are displayed vertically. Not sure why, that's how the xml was when i found it.

Here they are for 94170015:

<table name="Decel Fuel Cut Delay - Neutral A/C Off" category="Fuel" address="42bc" type="2D" level="2" scaling="uint8">
<table name="Load" address="675e" type="Y Axis" elements="7" scaling="Load"/>
</table>

<table name="Decel Fuel Cut Delay - In Gear A/C Off" category="Fuel" address="42ca" type="2D" level="2" scaling="uint8">
<table name="Load" address="675e" type="Y Axis" elements="7" scaling="Load"/>
</table>

<table name="Decel Fuel Cut Delay - Neutral A/C On" category="Fuel" address="42d8" type="2D" level="2" scaling="uint8">
<table name="Load" address="675e" type="Y Axis" elements="7" scaling="Load"/>
</table>

<table name="Decel Fuel Cut Delay - In Gear A/C On" category="Fuel" address="42e6" type="2D" level="2" scaling="uint8">
<table name="Load" address="675e" type="Y Axis" elements="7" scaling="Load"/>
</table>

 

Here is a comparison of bother the isc table and the decel fuel cut tables, 94170015 on the left and 96530706 on the right.

 

When revhang was an issue on the IX's we just changed the 41C column of that ISC Stepper table.

 

just what are we doing when we up a number on that map, what does the idle stepper do?
for example I was logging around 66 at idle warm car, bumped it to 80 and can't feel a change.

btw been using 706 for some time, and aside from some idle issues I have fixed for the most part( big cams), I don't see a reason not to keep it.

strange that the rolling to a stop idle kill hasn't hit me.

 

I believe that I remember seeing Mattjin mention that he decel fuel cut tables had a 1D load table as well. I don't think I have ever seen it defined though, but that may be a part of the puzzle that is different as well.

For starters, try lowering the decel fuel cut numbers and see if it helps.

 

All 05+ EVOs have that throttle hang. And Im guess since the 0006 ROm is a 05 ROM thats why.

Fiddling with the ISCstepper table can get rid of the hang, at the expense of messing up the cold start.

I believe the key to properly curing throttle hang is in the "Decel fuel cut delay" tables. But a lil hard to test since I have an 04 w/ 96420008 ROM.

I dont think that that table is deffined correctly or something.

In the begining of ECUflash, when I had my IX, I did a lot of messing with the ISC stepper table. I was able to find a good balance of gettin rid of the throttle hang and still having cold start, but I dont think that is the correct way to get rid of the throttle hang. Like I said above, I think it has more to do with the "Decel fuel cut delay" tables.

Also when i tried the ISC Stepper setting that I used in my car to get rid of throttle hang on another car, they experienced poor cold start and said throttle hang remained.

edit - oh mfr122887, you have them defined a lil different then my other ROMs do. Im my ROMs where these tables are defined, they are just numbered #1-4, and dont say "in gear A/C on/off" and "Neutral A/C On/off.

Seems like know those names will help a lil bit in figuring out how to get rid of the hang.

 

anyone got the definition for "decel fuel cut retard" for 9417?

 

yeah that big table used to have TPS on the X-Axis, I redefined it to use coolant temp - so you should only touch the right hand column... hence coldstart should _not_ be an issue!

 

also, if you read in this thread, I was asking about help defining these table for 94960011.

https://www.evolutionm.net/forums/ec...-two-roms.html

In that thread, matjin (sp) said that the #2 and #4 tables in 9496 were that same or something. read that thread for more info.

also, why is 9417 defined with "in gear A/C on/off" and "Neutral A/C On/off" and 9653 (and other ROM I have these tables defined in) have them listed just as "#1", "#2", etc??

 

look below. That is the table I developed using my IX, but even if you only change the far right column, there WILL BE affects on the cold start. Maybe you live some where where it doesnt get cold enough? Also like I said, I was able to mess with that far right column and find a good balance between getting rid of the hang and still having a reasonable cold start. (which is the settings below). But when I used these setting on a car in canada, the person had cold start issues.

But my point is, even if you only mess with the far right column, you CAN/WILL affect cold start.

 

Don't fiddle with the Idle stepper lookup table.
It just makes the rev hang happen at a lower rpm, but it still persists.

The reason why there is rev hang, is there is a table that adds a LOT to your idle demand (the vertical axis on the idle stepper lookup table) and causes the stepper position to go really high.

The tables I used to completely erradicate throttle hang were under the "ISCV Control" category:

- ISCV Demand RPM Adder [rpm > 4500, load > 170, speed > 12 mph]
- ISCV Demand RPM Adder (Moderated by Baro, IATS) (FFFF6EA8) (sub_204B6) [sub_1EFC0]

These two tables add up to 100% on top of your idle demand percentage and makes the lookup value much higher in the idle stepper lookup table.

Zero these two tables out, and log your iscv steps in evoscan.
You'll notice instead of going up to 120 or so when you accelerate hard, the iscv steps will only go up to around 70 instead, which will not induce rev hang. The iscv steps will also decay very quickly, since it won't reach such a high value like before. I haven't noticed any reduction in idle quality or part throttle driveability.

You may have to play with your Decel Fuel Cut Delay tables as well, but I don't know what the difference is between tables 1, 2, 3, and 4 are. I just made all my tables the same values as the ones in table 2 (this one has the lowest values and is the same as table 4).

Sorry for the long explanation, but it kind of makes it hard without pictures!

This post has a wealth of info on how the idle speed control system works.
https://www.evolutionm.net/forums/ec...sassembly.html

Go MrFred you are a legend!

 

Please tell me where can I find the xml definitions for the decel fuel cut tables on the 96530706 ROM, I have searched but not come up with anything.

Thx

 

this explains my cold start uber suck. Thanks for the information guys. I'll be contributing soon!

Do you guys have the recommended values for all the tables?

 

I am going to try this. Does anyone have the xml defs for those two tables for 94170015 just so we can compare? They were not in that thread.

Anyone know why the 2 roms have such different isc lookup values?

 

So from what i understand that lookup table is strictly a lookup table. We are not avoiding the issue by altering that. There are multiple tables that mrfred found that act as the adders for certain conditions that accumulate. I believe the ecu uses the accumulative value against that table. Therefore, i think making the values higher, not lower, could combat the issue but the real fix is either decel fuel cut or altering the adder values to not hit those sections.