Tephra v7 9653 thottle hang
Evolved Member
Joined: May 2009
Posts: 522
Likes: 2
From: mnt vernon ny
cool i did that. runs good now. the bounciness in the idle is kinda gone but it still doesnt wanna hit target idle. when i adjust the BISS screw to ecu idle value and locked the steering wheel it just stalls. urgh.. i mean i dont mind where its idling, its just the lack of control over idle rpm.I wish i could counter act that. also if i unplug the fiac should that affect the cars idle because mines doesn't im wondering if its bad... hope this isnt too off topic...
Last edited by hediki12; Dec 8, 2009 at 11:57 AM. Reason: tried to correct grammar and make it more readable.
cool i did that. runs good now. the bounciness in the idle is kinda gone but it still doesnt wanna hit target idle. when i adjust the BISS screw to ecu idle value and locked the steering wheel it just stalls. urgh.. i mean i dont mind where its idling, its just the lack of control over idle rpm.I wish i could counter act that. also if i unplug the fiac should that affect the cars idle because mines doesn't im wondering if its bad... hope this isnt too off topic...
Did you do the hot water bypass on your throttle body? If you did you need to reconnect the lines so the FIAC can operate properly. The wax inside it requires it to melt to operate.
I am glad the evo did away with that.
<table name="Decel Fuel Cut Delay #1" category="Fuel" address="36c8" type="2D" level="2" scaling="uint8">
<table name="Load" address="60a4" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Delay #2" category="Fuel" address="36d6" type="2D" level="2" scaling="uint8">
<table name="Load" address="60a4" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Delay #3" category="Fuel" address="36e4" type="2D" level="2" scaling="uint8">
<table name="Load" address="60a4" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Delay #4" category="Fuel" address="36f2" type="2D" level="2" scaling="uint8">
<table name="Load" address="60a4" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Ignition Retard" category="Fuel" address="370c" type="2D" level="2" scaling="Timing">
<table name="Engine Speed" address="5c6e" type="X Axis" elements="10" scaling="RPM"/>
</table>
<table name="Load" address="60a4" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Delay #2" category="Fuel" address="36d6" type="2D" level="2" scaling="uint8">
<table name="Load" address="60a4" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Delay #3" category="Fuel" address="36e4" type="2D" level="2" scaling="uint8">
<table name="Load" address="60a4" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Delay #4" category="Fuel" address="36f2" type="2D" level="2" scaling="uint8">
<table name="Load" address="60a4" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Ignition Retard" category="Fuel" address="370c" type="2D" level="2" scaling="Timing">
<table name="Engine Speed" address="5c6e" type="X Axis" elements="10" scaling="RPM"/>
</table>
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!
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!
So what is the conclusive answer on how to solve throttle hang ? ?
I have my way of solving it.
I was hopeing the OP could be updated with the solution. It will make searching for other people much easier to find the answer rather than sifting through tons of pages.
I have my way of solving it.
I was hopeing the OP could be updated with the solution. It will make searching for other people much easier to find the answer rather than sifting through tons of pages.
I find using 9417 decel fuel tables and the ISCV RPM adder tables does a pretty good job.
Ill have a sure fire way to eliminate it in a few weeks.
Last edited by Evo_Jay; Dec 21, 2009 at 11:15 PM. Reason: wrote down wrong info
The Decel fuel tables are the "fix". By lowering the numbers you decrease the time the fuel holds between shifts and when coasting. Pretty simple really. Actually I found that the values in the 9417 series roms offer a well rounded solution. The car will decel well and react quickly.
The Decel fuel tables are the "fix". By lowering the numbers you decrease the time the fuel holds between shifts and when coasting. Pretty simple really. Actually I found that the values in the 9417 series roms offer a well rounded solution. The car will decel well and react quickly.
I know the theory of it.
And I misspoke. I have been using the 9417 decel fuel cut settings and zero'ing the RPM adders. I think modifying the RPM adders are a good step in completely eliminating it, too.
But really, we wont have to deal with this for much longer.
Last edited by Evo_Jay; Dec 21, 2009 at 11:22 PM.
Joined: Mar 2003
Posts: 394
Likes: 7
From: Used to be in Nor Cal, now working in Seoul
I did this and the hang is still present. The RPMs are falling but not as fast as on 94170015 and the AFRs are not pegging lean. They bounce around between 12-16 until 3-3.5k RPMs then they go lean. Anyone know why they go lean at that point and not higher up in the rpm band?
I did change the decel fuel cut delay along with Appauldd's solution.
ISCV adders were all 0 from the start (phenem's V7 with mod rom), so I did not change them.
The whole delay used to be ~1.5 sec max from previous logs (94170008), but now it seems richer and longer only when decel after high rpm accel (over 5k rpm).
I read mrfred's advanced fuel control option thread, and it seems the Decel IPW substraction comp vs rpm only have values until 5000 rpm.
Did any one know a solution to this? Thanks.
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From: Tri-Cities, WA // Portland, OR
<table name="Decel Fuel Cut Delay #1" category="Fuel" address="3d6e" type="2D" level="1" scaling="uint8">
<table name="Engine Load" address="6fc6" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Delay #2" category="Fuel" address="3d82" type="2D" level="1" scaling="uint8">
<table name="Engine Load" address="6fc6" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Retard" category="Fuel" address="3da2" type="2D" level="1" scaling="Timing">
<table name="Engine Speed" address="6b7a" type="X Axis" elements="10" scaling="RPM"/>
</table>
...
<table name="Engine Load" address="6fc6" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Delay #2" category="Fuel" address="3d82" type="2D" level="1" scaling="uint8">
<table name="Engine Load" address="6fc6" type="X Axis" elements="7" scaling="Load"/>
</table>
<table name="Decel Fuel Cut Retard" category="Fuel" address="3da2" type="2D" level="1" scaling="Timing">
<table name="Engine Speed" address="6b7a" type="X Axis" elements="10" scaling="RPM"/>
</table>
...
thought i had gone thru all the iscv code. must have gotten burned out. still looking at the third table.
