Throttle hang and the Idle Stepper Table
Oct 4, 2006, 03:00 PM
#16
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Originally Posted by urBan_dK
I have seen this table in the ECU and I couldn't figure out why the axis values were so small (0-1016). All I can figure is maybe the person who created the map definition in XML couldn't figure out what this table did so they left the scale values as the literal hex values instead of multiplying by 8 or something to get a full RPM value.
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).
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).
Oct 4, 2006, 04:02 PM
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Originally Posted by ShiftySVT
I was wondering that too. Maybe the RPM axis isn't right. I'm going to adjust the values down in the table and log a run to see if the Idle stepper values are less and if the throttle hang is improved. I'll let you guys know what I find. It might have to wait till tomorrow though.
Oct 9, 2006, 11:27 AM
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This is a pretty well-known problem. I have it on my 03. Here is one of the threads:
https://www.evolutionm.net/forums/sh...ight=rpm+raise
https://www.evolutionm.net/forums/sh...ight=rpm+raise
Oct 9, 2006, 12:21 PM
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That is just the title of the thread. The "throttle hang" expression is more accurate. I noticed this in my 03, one month after I bought it in April 2003. Seems common in the eariler 8's. There has been a couple reports of an extra throttle spring curing it. I've just been living with it.
Oct 9, 2006, 12:41 PM
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I get different variations of this but mainly.....
Coming up on traffic, holding my constant speed/rpm I let off the gas. You would think it would start to decelerate, however, the car maintains its speed and rpm for a couple to a few seconds before it starts to decelerate.
Another variation is like someone stated before, you accelerate hard and when the clutch goes in, the rpms stays up for a few seconds until it comes down.....
Coming up on traffic, holding my constant speed/rpm I let off the gas. You would think it would start to decelerate, however, the car maintains its speed and rpm for a couple to a few seconds before it starts to decelerate.
Another variation is like someone stated before, you accelerate hard and when the clutch goes in, the rpms stays up for a few seconds until it comes down.....
Oct 9, 2006, 12:42 PM
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I think people are describing two different problems in this thread. I thought initially we were talking about just the problem on the 05/06 where the RPMs tend to go down slowly after being revved. I thought it was determined that this was due to ECU changes that were supposed to improve emissions.
The other problem I am hearing about in this thread sounds like a mechanical issue rather than an ECU one.
The other problem I am hearing about in this thread sounds like a mechanical issue rather than an ECU one.
Oct 9, 2006, 12:57 PM
#26
Originally Posted by urBan_dK
I think people are describing two different problems in this thread. I thought initially we were talking about just the problem on the 05/06 where the RPMs tend to go down slowly after being revved. I thought it was determined that this was due to ECU changes that were supposed to improve emissions.
The other problem I am hearing about in this thread sounds like a mechanical issue rather than an ECU one.
The other problem I am hearing about in this thread sounds like a mechanical issue rather than an ECU one.
This is why there is RPM hang. Its for better emissions. And only on 05 & 06 EVOs.
If RPM raises when your trying to shift, learn how to drive better.
Also, I have heard the Idle stepper table is different on the 03/04 ECUs. If you want to try to get rid of the RPM hang, try out the 03/04 table.
Oct 9, 2006, 01:06 PM
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Maybe. The perception of a problem is colored by your expertise. If you are mechanically inclined, you tend to think in terms of the CBV, throttle spring, clutch restricter, etc. If you are software inclined, you tend to think in terms of the ECU. Maybe it is two different issues, I don't know. Or, a combination of systems with the intent of slowing down the closing of the throttle, probably for emmissions control.
I mainly notice it shifting rapidly at high revs. Obviously, you try to let off on the throttle at the same time as disengaging the clutch. If some "system or systems" is holding the throttle open when you take the load off the engine, this may result in a raise in RPM. It depends on how much the throttle is open and how fast you are shifting as to whether the RPM raises or drops off slower than expected.
All I know for sure, is that it is annoying!
I mainly notice it shifting rapidly at high revs. Obviously, you try to let off on the throttle at the same time as disengaging the clutch. If some "system or systems" is holding the throttle open when you take the load off the engine, this may result in a raise in RPM. It depends on how much the throttle is open and how fast you are shifting as to whether the RPM raises or drops off slower than expected.
All I know for sure, is that it is annoying!
Oct 9, 2006, 01:14 PM
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What my prob is, is when i go WOT and take it to 6 or 7k and let off the throttle the car should "engine brake", but what happens is that the RPM remains where i lifted for like 10 seconds. Not all the time BTW. Also if i push the clutch in the RPM's stay where they were while i was in gear. It comes and goes and i am confident it is a ECU prob. I tried to coppy the tables from an 03 and still have the same problem.
Oct 9, 2006, 01:17 PM
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It feels like the car is using the Cruise control when i lift throttle. It continues driving and i get no engine braking. The throttle isnt stuck because it dosent continue at WOT, rather like ideling except at XXXX RPM.