As far as I can tell, The tension of the DV spring is partially the culprit.. and the "Stock" cars that I have seen experience it, have had their stock DV's installed backwards..

Take that with a grain of salt, but there's definitely something to be said about a properly adjusted Diverter Valve..

 

There is no RPM raise in my car, but RPMs hang longer than I would like them to after a high RPM shift. I initially attributed it to the heavy stock flywheel since I drove with a 12lb flywheel in my Subaru for over two years. Later I heard there was a restrictor pill to limit clutch dumps and figured it may cause the clutch to be a little slow when disengaging. One quick shift under some power and I felt the presence of the pill. Excellent, I thought, as that was considerably cheaper than the outrageous multidisc clutch/flywheel packages. In investigating the pill, I came upon this thread which almost mirrors the behavior I was experiencing on my very (read: COMPLETELY) stock car. Admittedly, I haven't spent any time isolating what conditions might allow this behavior to replicate.

-Jon

 

I'm glad I found this post. After reading this whole thread I think I'm experiencing the same issue as most of you guys.

Almost a week ago I did the first (and so far only) mod on my 05 Evo GSR, I replaced the whole TBE (DP/test pipe/cat back), since then I see spikes at high RPMs. I know for sure this is not a clutch related issue, nor driver error.

Let me explain: I started experiencing spikes on high RPMs when shifting. This spikes happened only when boosting, if I shifted at high RPMs but not under boost conditions, nothing weird happened. At low RPMs everything is fine. That shows you that this issue is boost related. Next, I thought it had something to do with my driving pattern, not letting the gas off soon enough, but eventhough I've been driving manual cars for ~20 years I didn't discard the idea. I confirmed that it was not a driver error nor a clutch related issue when I discovered that if I accelerate hard, then all of the sudden let off the gas (boost was built, RPMs @ around 5000), the RPMs will quikcly jump about 200 RPMs on top of whatever the RPMs were at that point, and this whole thing happened without even touching the clutch pedal.

I've been thinking that this issue could be related to the BOV failing to release all the pressure within the intake system, and the last posts may confirm it, however I'm not sure so I'd appreciate some input.

One last thing to consider, I have an 05 EVO so I have the launch restrictor (5K RPM limiter) still in use, on the other hand I have a remote starter installed so the clutch switch has been removed, I no longer need to press the clutch in order to start the car (if that matters in this issue).

Thanks.

 

My Evo does the same thing and I have posted all around the world looking for advice on it.

I would like to ask all experiencing this symptom / problem (as its real and a pain in the a$$) to please reach under the throttle body and remove the connector to the Idle Speed Control Valve (ISCV) small little connector with 6 wires, yes when its disconnected, it will probably stall, but restart and blip the throttle to keep it running, take it for a drive and see what happens, I bet you the problem has gone away, the revs drop normally...I will even put money on it ! just doesnt idle - so the ISCV is sticking in an open position when it should be closing - check if yours gets HOT as well, I am sure it fails due to temparature

Now the problem comes in - a replacement ISCV just fails again, so whats the point of replacing the stock one ? I have been digging around in the Hyundai parts bin as they used the 4g63 as well and the ISCV looks similiar but slightly different check electrical connections etc (its actually a mitsu branded part) so I am hoping for one that has more "toughness" built into it, I think a few members here and on other boards are aware of the trick to get this problem solved but they keep the answer very close to there chest, so its gotta be a simple ' duh why didnt I think of that....'

Please let me know your findings on this one

Cheers

 

Interesting read. I too am experiencing the rpm rise between shifts and at idle. Ive had the car a month, and it didnt start doing this until after the first time out to the track. Currently the car will run fine and drive fine, but I will notice that if I press in the clutch, the rpms will raise and remain between 2-3k rpm. Sitting at rest, with the gearbox in neutral, clutch in or out the idle will steady out at 1100 (hks 280/280's) and then climb to 2k... it will remain there for about 2 or three seconds and then drop back to the 1100rpms idle. Almost remeniscent of the DSM days when the IAC (Idle Air Controller) would fail...

I too am researching a fix, thinking that perhaps I have a vacume leak somewhere, but it seems far to common to be just tha. Im guessing something to do with the above mention IAC flaking out. Since people report the problem on stock to modified cars, perhaps Mitsubishi should be taxed with aiding a remedy. (don't hold your breath)

 

+1

I have the same thing after I install my greddy type-s. I put the stock bov back and the rmp only incrase 300 when i shifted from 1st to 2nd. With the after market bov it increases more than 1K.

 

same problem i have but like it only happens every now and then.


ANY ONE HAVE ANY UPDATES ON THIS??

 

Determined to be bov, injectors, dirty TB , or your just not letting go of the pedal all the way..yes I know it sounds stupid, but really pay attention next time you shift and make sure to take your foot all the way off before you even touch the clutch, just try and do it slow and work your way up and see if it still happens.

 

05's have this issue because the 05' ecu is programmed to keep the engine part throttle to reduce emissions..... 05's with the clutch switch disabled (for launching) will notice rpm's raising during shifts, this is because the ecu is not able to detect the clutch being depressed and therefore keeps the engine at part throttle even though you do not have a load on it (clutch pressed in). 05's with the clutch switch NOT tampered with, will notice occasionally when letting off the throttle, the car will 'keep going', same concept here, the car is kept p/t , if you press the clutch in, and release, the car will go back to closed throttle (hints the clutch switch to avoid having the car revving without load).

This make sense or did I confuse you all?

 

you confused me with how keeping hte car at part throttle reduces emissions

 

I have some more data, and some possible concusions.

1) problem only occurs in cold weather => dense air matters
2) tapping the brake instantly stops the rpm surge => ECU matters
3) I have a WORKS/GFB adjustale hybrid BOV. If set to full recirc there is no problem. If set to partial or full VTA, rpm surges. This behaviour is reproducable every time. The degree of VTA needed for an rpm surge depends on how cold it is. On a hot day 50% VTA is no problem, on a very cold day any VTA triggers rpm surge.

Theory:

1) there's definitely software involved (ECU) - the problem is so difficult to pinpoint, because it involes the ECU's response to a specific set of conditions, and the conditions depend on weather (air density), BOV behaviour, and possibly back pressure from the intake filter.

2) The 05's have this behaviour because the ECU was programmed differently than preceding models. Other cars may show similiar symptoms, but they are caused by a different problem (e.g. throttle spring, dirty injectors, etc.). People who tried VTA BOV's on '05 cars have reported no stalling problems, while earlier versions do have stalling problems, again indicating different programming for the ECU / MAF operation.

3) Disconnecting the clutch switch fixes the problem for some USDM vehicles, because the clutch switch connects to the ECU - you cannot start the car without depressing the clutch. Pressing the clutch(switch) also changes the A/F during shifting, supposedly leaning it to improve emissions. So when you disconnect the switch, you change the input the ECU sees during a shift and prevent the specific "input pattern" that causes the rpm surge. I don't think this is a reliable solution though.


Possible Work Arounds:
1) warm weather (yeah I know .... can't bolt that on)
2) don't VTA (unless you are stock already)
3) clean your air filter
4) verify proper operation of the clutch switch

The only true solution:
Fix the problem. IMO the problem is software, the ECU programming responds in a way that is undesireable. Whether or not this behaviour was intended by mitsu is hard to say, some people have suggested this is a feature, like anti-lag of some sort that kicks in when driving hard. It still annoys me, and I wish this feature was gone, but thankfully I only see it 3 months out of the year (as long as I don't VTA > 20% and keep my filter clean).

 

This has happned in my 05 from stock till now.....but only when at a rapidly reached high rpm (6000+) and pushing the clutch in quickly and going to neutral.......DAMN this is driving me CRAZY lol

 

so with this data can someone hand this problem to a flasher and have them remedy your clutch in lean condition????

 

Well mine started doing this after my exhaust install! Two times since saturday !

 

I really haven't read all the replys on this thread but I'll tell ya this... I have an 06 IX and once I got 500 miles on the car I started to do some spirited driving. This is not a "normal" situation and I can drive. I've had about 10 DSM, 4 GVR4's and have driven a bunch of evo's that don't do it at all!

In my experience I notice it most say you start to accelerate on the hard side then abruptly put the clutch in and let off the gas. Let me paint a picture. Say you start to romp it and get to about 5K rpms and someone ahead pulls out of a parking lot. Naturally you let off, throw the clutch, and brake. All the while for say 3 seconds the car continues to rev at 5K rpm then very slowly falls to idle but taking an additional 2-5 seconds to fall. It was so bad the first few times it did it I thought my throttle cable was stuck or the plenum was stuck open. I'm researching it here and having my shop foreman look into it. Maybe we'll find a clear solution. It's not mod or clutch specific in my case (however those things might effect the overall intensity of it) since my car only has an exhaust and did this problem before that was put on.