I've had my Evo VIII for two years now, and the idle has always stabilized at around 1100-1200 rpms, which I thought was high, considering my DSMs always idled between 750-850. I never gave it much thought however, since other than that, the car has always run fine. Four times during the past winter, I got intermittent CELs for a random misfire in Cylinder 3, but they would always clear themselves after a day or so. Its been at least a month now since the last time the CEL came on. This past week, I noticed that my idle was fluctuating a bit once the car was warmed up. Sometimes the idle will randomly rise to about 1300-1500 before dropping down to 1100 again, but more often, it will drop to 900 and the engine sounds like it has cams in it. As you can see in the video, the tach doesn't register a jumpy idle, but you can definitely hear it in the exhaust note.

-I got the 60k mile service done about 10k miles ago, so the plugs are brand new.
-I don't have much free time off from work, so I haven't gotten the chance to do a boost/vacuum leak test. It has the stock plastic bov though, so there's a good chance thats at least a boost leak by now. I do have a bluetooth ODBII adapter that I use to get codes and data from the ECU, and that tells me my vacuum at idle is around -18.7 in/hg.
-Not sure if its related, but my SRS light came on a couple weeks ago. I had been digging around underneath the driver-side seat after I lost something, so I'm not sure if I bumped an airbag connector and thats what tripped that.

 

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Im very interested in what you find out. I have a similar issue. Except mine has idled like that ever since I got the car so I just thought that was a normal thing. Thinking now maybe its not or possibly has gotten worse over the 3 years i've owned the car and I just didnt notice.

Mine is a stock Evo IV engine in an Evo VIII. The guy I bought the car from said last night that it sounded like a dead miss at idle but its a consistent idle at about 1000 rpms.

I also have an AEM V1 so I don't get CELs so I don't know if its missing on a cylinder or what. I need to do a comp and leak down test though.

I'm hoping its like a cracked oil ring or bad piston or something so that when I build the new engine that goes away.