Throttle hang and the Idle Stepper Table
Sep 30, 2006, 08:19 PM
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Throttle hang and the Idle Stepper Table
I've noticed on my IX that after hard acceleration, it feels like the throttle is still cracked open. There's almost no engine braking. In fact it feels like it slows down faster if you take it out of gear. I looked at some EvoScan logs and the ISC Steps (I'm assuming this is related to the Idle-Air Control Valve) climb to 120 when I'm on the throttle. After getting off the throttle, the ISC steps slowly decrease as RPMs fall. In normal driving this probably improves drivability by smoothing out off-throttle abruptness. However in spirited driving it feels like it's seriously hurting braking performance. I'd rather my right foot be in control of the amount of air to the engine instead of the computer taking over.
Has anyone tried to fix this with ECU flash? I see there's an Idle Stepper Lookup Table, but it only applies to very low RPM (0-1016). If the RPM axis was 0-8000 it would make perfect sense. I could just decrease the values and see what happens. I understand that 03 and 04 Evos don't suffer from this nearly as bad. Any ideas where the difference is? Could someone share their idle lookup table from an 03 or 04?
Has anyone tried to fix this with ECU flash? I see there's an Idle Stepper Lookup Table, but it only applies to very low RPM (0-1016). If the RPM axis was 0-8000 it would make perfect sense. I could just decrease the values and see what happens. I understand that 03 and 04 Evos don't suffer from this nearly as bad. Any ideas where the difference is? Could someone share their idle lookup table from an 03 or 04?
Last edited by ShiftySVT; Jan 17, 2007 at 03:03 PM.
Oct 2, 2006, 03:16 PM
#2
Originally Posted by ShiftySVT
I've noticed on my IX that after hard acceleration, it feels like the throttle is still open cracked open. There's almost no engine braking. In fact it feels like it slows down faster if you take it out of gear. I looked at some EvoScan logs and the ISC Steps (I'm assuming this is related to the Idle-Air Control Valve) climb to 120 when I'm on the throttle. After getting off the throttle, the ISC steps slowly decrease as RPMs fall. In normal driving this probably improves drivability by smoothing out off-throttle abruptness. However in spirited driving it feels like it's seriously hurting braking performance. I'd rather my right foot be in control of the amount of air to the engine instead of the computer taking over.
Has anyone tried to fix this with ECU flash? I see there's an Idle Stepper Lookup Table, but it only applies to very low RPM (0-1016). If the RPM axis was 0-8000 it would make perfect sense. I could just decrease the values and see what happens. I understand that 03 and 04 Evos don't suffer from this nearly as bad. Any ideas where the difference is? Could someone share there idle lookup table from an 03 or 04?
Has anyone tried to fix this with ECU flash? I see there's an Idle Stepper Lookup Table, but it only applies to very low RPM (0-1016). If the RPM axis was 0-8000 it would make perfect sense. I could just decrease the values and see what happens. I understand that 03 and 04 Evos don't suffer from this nearly as bad. Any ideas where the difference is? Could someone share there idle lookup table from an 03 or 04?
It would be great to have the ISCV chop the rpms quickly when the rpms are above 4000rpm yet still do its magic for improved gas mileage and emissions control.
Any input on this would be super.
Oct 3, 2006, 05:10 PM
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Originally Posted by ShiftySVT
I've noticed on my IX that after hard acceleration, it feels like the throttle is still open cracked open. There's almost no engine braking. In fact it feels like it slows down faster if you take it out of gear. I looked at some EvoScan logs and the ISC Steps (I'm assuming this is related to the Idle-Air Control Valve) climb to 120 when I'm on the throttle. After getting off the throttle, the ISC steps slowly decrease as RPMs fall. In normal driving this probably improves drivability by smoothing out off-throttle abruptness. However in spirited driving it feels like it's seriously hurting braking performance. I'd rather my right foot be in control of the amount of air to the engine instead of the computer taking over.
Has anyone tried to fix this with ECU flash? I see there's an Idle Stepper Lookup Table, but it only applies to very low RPM (0-1016). If the RPM axis was 0-8000 it would make perfect sense. I could just decrease the values and see what happens. I understand that 03 and 04 Evos don't suffer from this nearly as bad. Any ideas where the difference is? Could someone share there idle lookup table from an 03 or 04?
Has anyone tried to fix this with ECU flash? I see there's an Idle Stepper Lookup Table, but it only applies to very low RPM (0-1016). If the RPM axis was 0-8000 it would make perfect sense. I could just decrease the values and see what happens. I understand that 03 and 04 Evos don't suffer from this nearly as bad. Any ideas where the difference is? Could someone share there idle lookup table from an 03 or 04?
This is pure speculation, obviously. If someone has guts and more experience than me with tinkering, maybe the values in this table should be tweaked slightly to see if the RPM hang behavior is mitigated (or worsened).
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Oct 4, 2006, 07:42 AM
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This is a common problem. My throttle does not hang up anymore. While installing my SS clutch line, I took the restrictor out of the slave cylinder. It looks like a little poppet valve with a spring attached that can easily be removed by removing the banjo bolt on the bottom of the slave cylinder. The only pain was bleeding the cylinder again.
I believe that Mitsu installed this valve because of how weak the stock clutch is in our cars. As far as curing this with EcuFlash I have no idea.
I believe that Mitsu installed this valve because of how weak the stock clutch is in our cars. As far as curing this with EcuFlash I have no idea.
Oct 4, 2006, 07:50 AM
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Originally Posted by GGEVO2k5MR
This is a common problem. My throttle does not hang up anymore. While installing my SS clutch line, I took the restrictor out of the slave cylinder. It looks like a little poppet valve with a spring attached that can easily be removed by removing the banjo bolt on the bottom of the slave cylinder. The only pain was bleeding the cylinder again.
I believe that Mitsu installed this valve because of how weak the stock clutch is in our cars. As far as curing this with EcuFlash I have no idea.
I believe that Mitsu installed this valve because of how weak the stock clutch is in our cars. As far as curing this with EcuFlash I have no idea.
Oct 4, 2006, 09:04 AM
#11
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Originally Posted by GGEVO2k5MR
This is a common problem. My throttle does not hang up anymore. While installing my SS clutch line, I took the restrictor out of the slave cylinder. It looks like a little poppet valve with a spring attached that can easily be removed by removing the banjo bolt on the bottom of the slave cylinder. The only pain was bleeding the cylinder again.
I believe that Mitsu installed this valve because of how weak the stock clutch is in our cars. As far as curing this with EcuFlash I have no idea.
I believe that Mitsu installed this valve because of how weak the stock clutch is in our cars. As far as curing this with EcuFlash I have no idea.
Oct 4, 2006, 10:08 AM
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I also had a flash and still had the issue as well...I did notice it went away when I took the restrictor out, changed to the SS clutchline, and put my exedy twin HD in. The restrictor in the clutch line regulates how much of the fluid goes through the line. Its about the size of a pin hole and when removing it allowed the fluid to flow better.
Im not trying to give false information here. Its just from my experience the hanging rpms went away after doing this.
Im not trying to give false information here. Its just from my experience the hanging rpms went away after doing this.
Oct 4, 2006, 11:32 AM
#14
There is another possible cause of the symptom, when I was testing different Diverter valves, the more tightly springed they were, the more likely you would get the RPM raise between shifts.. Since the IX valve is springed firmer this can also contribute to the issue..
HOWEVER, this is just a partial cause, the Base Idle Speed Setting is a bypass valve, as is the Idle Stepper Control Valve, both let air past the throttlebody, and when you have a firmly springed valve, slight excess boost pressure, and a ICSV setting or BISS setting to increase idle speed to prevent some types of stalling, you will get the idle hang/raise..
HOWEVER, this is just a partial cause, the Base Idle Speed Setting is a bypass valve, as is the Idle Stepper Control Valve, both let air past the throttlebody, and when you have a firmly springed valve, slight excess boost pressure, and a ICSV setting or BISS setting to increase idle speed to prevent some types of stalling, you will get the idle hang/raise..
Oct 4, 2006, 03:00 PM
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Maybe what i am experienceing is a little different. After a WOT pull i may let of the gas at any given RPM. Usualy above say 4k, the car fells like the cruise control is on. I get no engine braking and it will just continue to cruse along at that RPM. Its defenetly not a stuck throttle cable BTW.