ok this is the situation, around November 2009, the car was functioning perfectly, would boost 0.9 in all speeds maybe a bit more in 3rd and 4rd 5th, I just put the car home, 2 days later went for a drive and the idle was acting weird, the idle RPM is perfect at ~850
but the vacuum is between -0.4 and -0.5 , it keeps moving around, it used to be -0.6 , when i turn on the AC it goed to -0.3 with little fluctuation, then after a min or so hops to the -0,4 and -0.5 fluctuation and goes back to ~-0.3... the boosting was good the same at first, but after this isue has been here a while the 1ste boost 0.8 and 2nd also, and 3rd 4th 5th goes to 0.9 bar dont know if this is a coincidence but i notices this after doing compression test and checking the wastegate, i put air into the wastegate hose to see if it moves(it did, dont know if it got damaged? :S), i checked spark plugs changed to iridium, did boost leak and found the throttle body leak, fixed that leak and didnt change anything, still same issue, did a compression test ( all cylinders reached past 150 i think), no check engine light on, did a test with evoscan for fault codes, found nothing, changed the coil wires, same issue. the car drives great , idle is good if i rev to 1200 RPM vacuum would stay at 1 level, car drives normal without hesitation or anything.
today i noticed i have a boost drop issue also, in all speeds it drops at least 0.1 bar after 5k RPM

any help, i've been suffering with this problem for a while and its driving me crazy

 

any help anyone ?

 

Can you break that one massive sentence into coherent thoughts?

I get lost every time I try to read it.

 

ok the car used to run fine every speed boosting 0.9 bar.. and idle good

now:
-doesn't idle good, misfire
-idles at steady 850RPM which is good
-idle vacuum is moving between -.6 and -.5
-idle when ac on , fairly good at -.3
(using a bar boost meter)
-car has boost drop of 0.1 bar in gear 1 - 3.. 4th 5th gear boost doesn't drop
-when i rev the car to 1200 RPM the idle vacuum doesn't move like them its idle and the car doesn't look like that is misfiring
-idle sounds like the car has cams , but it doesn't

what i did:
-changed sparkplugs
-changed sparkplug wires
-used evoscan dtc codes , found nothing , and have a new version of evocan and every time it just gives me like 8 different codes i do it (think evoscan is not working for it)
-did a engine compression test, good, all 150
-did a boost leak and found the throttle body shaft seals leaking, changed that and the car does exactly the same
-no check engine light

 

a couple of videos i made of the idle : http://rapidshare.com/files/376684051/Evo_Idle.zip

 

did you ever find this problem? also put videos on youtube that way i can see them... my evo is doing this and iv done so much **** replacing and nothing has changed. still gos well but idle sound is like cams but they are standard i think no hks or anything on them

 

Have you recently done any mods to it

 

If its an unstable idle check that the battery terminals are tight and that your grounding is good. Then start checking idle screw etc.

 

i have a grounding kit installed on mine.. i have gone to a new bov and air filter gfb bov and hks air filter. the idle on the gauge sits nice and strong. but the engine rocks and pops and farts driving me bloody crazy iv had timing checked was dead on i replaced the air flow meter with evo 7 that made it run better for a few days then got worse so i put evo 4 item back on...the throttle body was replaced not long ago so im sure its not that... all my vacuum lines are good iv gone over them a millions times...

 

I have the same problem mate!, i will post videos of the car working and see if yours is the same

 

Cas?sometimes heat kills these and causes the car to run like what you have said. Do u have an upgraded fuel pump?

 

yea mate ill do same this weekend...

 

cas?? whats that.. no not that i no of

 

I posted the video on metacafe:

http://www.metacafe.com/watch/7253421/idle/

Does yours do the same?

 

yea it was.. but i think i may have fixed mine. im not sure tho as its still lumpy sometimes. but i replaced one hose that runs from fuel reg back to the plug thingy lol .. plus i also replaced the hose that runs from the standard boost controller solenoid to the intake part and it seems to be ok.. heres a pic of parts i move/replaced. as i was taking photos i noticed that i could spin my bov!! lmfao it fell apart when i pulled of!!!.. gave a clean up and put back on fingers crossed!