Throttle hang and the Idle Stepper Table
Sorry people for time lapse.
Here's the scoop, in my case at least. In order for me to push the boost holding of the DV to the max I rigged a contraption that basically vents the air underneath DV diaghram through an internal port I added.
The solenoid which basically closes the port between shifts is not openeing fast enough so there is about a 0.5 sec lag in time. The air is trapped on the charge assembly long enough to overcome the TB springs. Even though foot is off throttle the forward direction of air is felt at the MAF as if it was floored.
I have a spare intake manifold/TB assy with all the attached solenoids (garbage for some, my treasure
) laying around and I cannibalized one of the two TB springs and I managed to retrofit it to the two existing springs.
My original attemp on this fix was for troubleshooting purposes only and even though I'm totally satisfied with it as is, I'm going to have to eventually come up with a more technically sound and permanent fix to the spring tension, like a thicker guage spring. Nonetheless, the car is so much more fun to drive.
Just a caution: Keep in mind that adding a spring to that area can cause the throttle to stick wide open if it's intalled in such away that it may get stuck, and it's not really a fix as yet - just a diagnosis
Also keep in mind that throttle hang can be caused by other things other than what I was experiencing with my highly rigged and modestly modified stock turbo evo at 27 psi boost. The 2005 evo's were known to have a between shift rpm maintaining system built into it for some insane reason. So make sure it isnt that first
Here's the scoop, in my case at least. In order for me to push the boost holding of the DV to the max I rigged a contraption that basically vents the air underneath DV diaghram through an internal port I added.
The solenoid which basically closes the port between shifts is not openeing fast enough so there is about a 0.5 sec lag in time. The air is trapped on the charge assembly long enough to overcome the TB springs. Even though foot is off throttle the forward direction of air is felt at the MAF as if it was floored.
I have a spare intake manifold/TB assy with all the attached solenoids (garbage for some, my treasure
) laying around and I cannibalized one of the two TB springs and I managed to retrofit it to the two existing springs.My original attemp on this fix was for troubleshooting purposes only and even though I'm totally satisfied with it as is, I'm going to have to eventually come up with a more technically sound and permanent fix to the spring tension, like a thicker guage spring. Nonetheless, the car is so much more fun to drive.
Just a caution: Keep in mind that adding a spring to that area can cause the throttle to stick wide open if it's intalled in such away that it may get stuck, and it's not really a fix as yet - just a diagnosis
Also keep in mind that throttle hang can be caused by other things other than what I was experiencing with my highly rigged and modestly modified stock turbo evo at 27 psi boost. The 2005 evo's were known to have a between shift rpm maintaining system built into it for some insane reason. So make sure it isnt that first
Remember, this table is no different than others in the rom, if you exceed the value in the table, it probably uses the last value in the table.
Its obvious that the car can tell the difference between whether the car has the clutch-in or clutch-out (as the values for idle in "Neutral" and "Drive" do exist in the rom)
The throttle spring solution is only for excessive residual pressure that can blow the throttle blades open, but this is really only a solution for the problem when RPM Rises and not a throttle hang.
If modifying the table works, and it doesn't cause drivability problems in stop and go situations, then you have your solution.
There are 3 other tables often overlooked that can be relevent
Desired ISCV intial step position with AC off-Neutral
Desired ISCV intial step position with AC off-Drive
Desired ISCV intial step position with AC on-Neutral
Desired ISCV intial step position with AC off-Neutral
Desired ISCV intial step position with AC off-Drive
Desired ISCV intial step position with AC on-Neutral
I just got my car outta storage, so i am going to give the idle stepper table fix a shot and report back.
Evolving Member
iTrader: (4)
Joined: Mar 2003
Posts: 124
Likes: 0
From: Walnut Creek CA (SF east bay area)
Thank you all so much, this is great info. MalibuJack your contributions as always greatly appreciated. BTW I now run the Dejon Tool stop leak setup with their diverter valve and its clearly the best diverter solution I've found for my car with the 3076 turbo, espically in track use.
hey V.8MR, the table adjustment worked well for you? what do you mean you have no warm up mode? what does the car do? or not do? And Tuner, as far as the dejon tool is concerned, did this fix the issue for you 100%? and shoudl it work the same with the stock turbo and intake? thanks guys
hey V.8MR, the table adjustment worked well for you? what do you mean you have no warm up mode? what does the car do? or not do? And Tuner, as far as the dejon tool is concerned, did this fix the issue for you 100%? and shoudl it work the same with the stock turbo and intake? thanks guys
Evolving Member
iTrader: (4)
Joined: Mar 2003
Posts: 124
Likes: 0
From: Walnut Creek CA (SF east bay area)
Jersey Dino,
Yes, the Dejon Tool leak stopper/diverter valve pretty much eliminated surge issues. We never used it on a stock turbo but it would work very well with any setup, I'm sure.
Yes, the Dejon Tool leak stopper/diverter valve pretty much eliminated surge issues. We never used it on a stock turbo but it would work very well with any setup, I'm sure.
Evolving Member
iTrader: (4)
Joined: Mar 2003
Posts: 124
Likes: 0
From: Walnut Creek CA (SF east bay area)
Throttle hang up
Ok, so we ran our red Evo at Thunderhill last Sunday with the newly scaled (using 30s) ISV map. Everything worked great. No more of the feeling of fighting the engine with the brakes on some of the corners. Our pad life went way up - ran 165 miles on the track (2 drivers) in 8 sessions and only used 5-6 mm of front pad on our Alcons. This is much better than past wear with this car. When cold it does not idle well but it only takes a short time to smooth out. As far as I'm concerned this issue is solved for us.
Regarding those other three ISCV tables, I did some checking. It seems that the 05/06 roms are different then the 03/04's on those tables. The idle stepper table from the 03/04 wouldnt help because its actually higher values in upper rpm, all the way to 160's. But check these out...this is an 03 rom on the left, and my IX on the right:
I dont have this problem for some reason, so no use me trying it out. But someone try copying the settings from the ones on the left to their tables. From top it is in this order:
AC Off Neutral
AC Off Drive
AC On Neutral
The AC on Neutral are the same, so dont worry about those. I just left those in for reference. Someone try it out!
I dont have this problem for some reason, so no use me trying it out. But someone try copying the settings from the ones on the left to their tables. From top it is in this order:
AC Off Neutral
AC Off Drive
AC On Neutral
The AC on Neutral are the same, so dont worry about those. I just left those in for reference. Someone try it out!
Im willing to bet money on this actually. The more I look at it, the more it makes sense. The IX tables on the right in the AC Off Neutral (top right) are way higher then the 03's table to the left. I bet you could just change those last two values (102) to the values from the 03 and fix this. That way your cold idle wouldnt be affected, but once warm it wouldnt hang anymore.
Someone test my theory
Someone test my theory