i had a really bad case of rev hang, but it did not hapen with any mods or tuning, it just started one day. after spending many days trying to figure out the problem and goign over every component on the engine we notices a slight crack on one fo the vacuum lines goign to the fuel pressure regulator. after replacing this line no more rev hang. check for slight vacuum leaks those seem to cause rev hang if they are situated oin certains points on the car

 

i have the same problem on my brand new evo 9. i dont think it is possible for brand new cars to crack vacuum lines. . a lot of people are having this issue perhaps the car is simply built this way.

 

My solution is... Clean insdie of BOV and Egde of piston BOV for erase all oil, new line-vacumm bov to intake and un-plug conector swicht clutch, is rear pedal clutch.

Important, "NO!!!" VTA Bov in your evo, only recirculated BOV. HKS+Kit rec or Greddy type-s with one large spring o MR BOV.

 

Those of you who have fixed this issue permanently - WHAT DID YOU DO??

 

I never thought of it as an issue ? The RMP's staying up between shifts is a good thing IMHO.

 

bump... rpm shoots up doesn't rise....

 

this happens to my car too... im thinking its possibly a clutch related issue? but im not sure.

 

solution? mine does this. Evo 9

 

Mine has been doing this since I bought it a year ago. I am no self tuning, and one of the issues is that my TPS reading in ecuflash doesn't seem accurate. I have had this behavior exactly like all the others. One more description from me is that it seems like the car doesn't have any throttle steps below 25%.

i.e. driving in traffic is impossible. It just bucks like a light switch. On throttle and then Off.

I also have the RPM rising stuff between shifts.

I can do it in neutral and just rev the engine, it still stays higher and lags on the return. I cleaned the Throttle Body thoroughly when I bought the car because of this.

Does anyone know if the TPS is adjustable?

If you adjust the cable tension do you mess up the TPS reading?

Any ideas greatly appreciated.

Thx M

 

mine has been doing this well. stock clutch. put in a new exedy same thing. only different thign was that it started after getting a Samco sport DV valve, fp red, switching to e85.

 

My car is also doing this, 2007 Evo 9 with only 30,000kms.

Cleaned throttle body but that still didnt fix it, only made the problem slightly less noticeable, except in higher gears and higher RPM.

Anyone know what could be causing this issue, and if there's a permanent fix?

Its doing my head in!

 

While many are having the same symptoms, they weren't always caused by the same problem. You should read through the thread to make yourself a list of things to check. Start with the easiest/cheapest, obviously.

Last sat. I was at a track day, and in the middle of a lap I suddenly started having the same problem; RPM raising during shifts. When I got home that night I searched EvoM for others who may have had this problem and came across this thread. Then it occurred to me that my floor mats might have moved during a turn on the road course, and the pedal may have been getting stuck in the mat (It was only happening at WOT, and I have rubber winter mats on top of the stock mats to protect them). I checked the mat and made sure it was positioned correctly, and what do you know! Problem solved! I missed half a day of lapping because of such a silly problem, since I parked the car for the day when it started. I did get to ride shotgun in a SC'ed Elise though, so it wasn't that bad

 

You left floor mats in your car on a track?
I experienced throttle surge on shifts last weekend in my track Evo for the first time in 5 years. I believe it's either the idle stepper or some new intake and intercooler pipe angles in which air is getting caught. I'll have an answer next week.

 

Yea - last time I do that

 

This might sound weird but I used to have this problem after tunes and also after disconnecting/reconnecting the battery. After a while it goes away until I do one of those two things again.

I also noticed it will sort of hang there for a few seconds until I press the clutch in.