Mine did this when it only had 1k miles on it and still does it to this day with the flash. The throttle body seals could probably cause this also but I think its a program issue.

 

yeah, if it has been since it was brand new, then you can pretty much rule out shaft seals, unless they wern't lubed when manufactured.

 

mine has done it since i bought the car with 5 miles on the clock. many others also.
i just chalked it up to drive by wire. it hangs over 3Krpm, and magically starts engine braking when it goes under.

its by design - its not a mechanical problem. hence why people keep asking how to get rid of it using ecuflash.

 

Hopefully you aren't talking about an EVO...

EVO's don't have drive by wire...

 

It has to do with emissions.

Right now, there's nothing we can do bout it. Just live wit it.

Also, the EVO DOESN'T have drive-by wire. lol

 

OK, this is the 2nd thread I have posted this in, but I want to read what everyone has to say, so sorry for the re-post...

Oh THANK GOD for this thread...

I have driven my BRAND NEW IX MR for a total of 80 miles, and within the first 10 miles I remarked about this throttle hang. I said to my friend "this flywheel must be a thousand pounds!"

My background is with Toyotas, and toyota's ECUs and programing are pretty rock solid, so the first thing I was thinking was mechanical. Here were my thoughts.

1) Heavy flywheel / rotating mass causing inertia to keep RPMs high
2) Throttle plate sticking slightly open (pressure, or friction)
3) Throttle plate doesn't seal (doubtful as idle is controlled low)
4) Stock BOV/Diverter valve not releasing pressure, causing throttle plate to stick open.

Those with you with data logging, I would love to see the following perameters:
Throttle Position
Manifold pressure
IAC position
MAF voltage
Injector percentage.

Basically, if we see throttle position not closing, then it's a mechanical problem
If we see the throttle position fully closing then it's a software problem

Lets look at the symptoms... then let's look at the cause of those... then let's look at the cause of THOSE and go from there. once we know all the causes, we can fix them.

Symptom - RPM "hangs" after throttle closes.
Cause
Theory - Inertia keeping RPMs high, Solution: lower rotating mass
Theory - injectors are being cut causing a lean condition, and a lean power increase... (HIGHLY doubtful, but still to test)
Theory - air being vented into manifold, Cause: throttle plate open? IAC open?

Test the throttle plate... what is the voltage of the throttle plate when closed and this condition occurs. If the throttle plate is fully closed, we can eliminate the Diverter valve as a problem as well...
Test the IAC... unplug it, and see if the hang is fixed

I've been reading these forums for a couple weeks now, and it seems that any time there is a problem, people use the "boomerang solution"... This means to throw a part/software change at it and see if it comes back. Lets look at the causes and fix those.

of course I would love to do these myself, however my car is in Arizona, and I am in Wisconsin for the next month... so I can't check these myself.

Good luck guys... hope I've helped somewhat here

 

does it have anything to do with the EGR system?
does it recirculate when you let off the throttle, that could explain how its still hanging even when the throttle plate is closed?

as for the drive by wire - forgive me i'm coming from old school hondas - and hondas started to do the same thing when they switched to drive by wire - so i only assumed.

 

There has been enough research on this that it really has been isolated to a few common things, both mechanical and ECU related. The newer unmodified cars definitely seem to be ECU Related.

The RPM Rising is the other issue you seem to be describing. That could be due to excess air getting through the throttlebody, due to inadequate venting of the DV, leaks, etc.. This is REALLY common with stiffly sprung DV's as the surplus pressurized air tends to bypass the throttle plate through the BISS and Idle Stepper before the ECU cuts fuel.

 

bump to keep alive

 

Interesting, mine is 3500 and there is no mistaking when it happens for those that are wondering IF their car does this.

I will run checks on my mechanical parts, as for tuning, I can have Ivey check that.

 

cross link to the solution - https://www.evolutionm.net/forums/sh...226466&page=10

 

Good job

 

Bump need a cure,i'm not sure about your cars but with mine if i push in the clutch it will hang after i get on it.i have found that if i double clutch it let the clutch out then push it back in they drop normal,this would lead me to believe that it is computer controlled and not TB seals.

 

I posted cure that worked for me on the thread dexmix linked to, on page 13. Make sure your desired idle RPM - Drive table is set to stock, sometimes it gets changed when tuned.