I am having a few issues with the Evo 9rs that I just purchased a few days ago. Yes, I have tried to research my issues before posting here. For starters, it always sounded like it has a cam but it does not. The idle lopes like it has a cam once it is warmed up. (My research has lead me to believe that this is a EGR CONTROL SOLENOID correct me if I am wrong). The second day I drove it, the car had a fluctuating idle when you would drive it over 15min. When stopping or just putting the car in neutral the RPM would jump from 1000-1500RPM three times or so and then drop to around 500RPM. My wideband would fluctuate lean and rich when It did it. The CEL came on with a p0134 code which was the oxygen sensor. I had my friend clear the code and replaced the oxygen sensor with a Denso 2344741 sensor. This did not solve the problem, I still have the fluctuating idle once the car warms up. It is not throwing any CELs either. I cleaned my MAF sensor as well. Any ideas?

 

Have you checked out your MIVEC map? You can get a lope at idle with a modified MIVEC map.

 

I don't believe the mivec map is modified. I can have my friend double check.

 

All help is greatly appreciated!

 

The Mivec map is fine. It looks like stock in the idle(low load, low rpm) area. It sounds like the exhaust has hiccups between every few revolutions of the engine. Logging the car showed that the idle rpm and timing advance don't sit very steady at all. Sometimes the timing advance during idle goes a few degrees less than what is in the timing maps when it is swaying up and down.

Edit: Might I add you can't visibly see the tachometer needle moving when its idling. I was talking about the idle rpm in Evoscan.

 

Tps?

 

TPS signal reads steady.

 

Here are a couple things I would check:


Aftermarket injectors scaled properly? Injector stuck open? All plugs and coils good ? Timing marks on cam gears and oil pump pully line up ok ?

Best of luck to you.

-pal215

 

Check for a bad coil pack.

 

I would check your MAF. If you know another Evo owner close by, try doing a quick swap and see if you notice a difference.

My car used to have a minor hiccup (felt like a slight misfire) in the idle that got noticeably worse whenever I tried running larger injectors. I decided to try and clean it one day with MAF cleaner and at first it ran much better. But then about 2 days later it started running a lot rougher at idle. I swapped the MAF and it solved the problem.

 

I had a similar issue and my blow off valve was actually too tight. Are you running an atmospheric bov with the stock maf?

 

I've had this issue with my Evo 9 for over a year now, it just started one day. Since then I've changed the turbo, cams, converted to speed density, changed to closed loop, deleted the ERG, redone the timing (when putting in the cams), cleaned up the head and lapped the valves, new plugs, taken out the spoolin cop and put the oem coils back in, taken out the injectors and put the oem ones back in, all to no effect. I'm not getting any codes and the idle is rough (taking the cams into account) with a constant misfire sound, when coming into corners off the throttle the car has a warbly semi backfire thing happening. I've run out of ideas how to fix this. The blowoff is a oem metal Evo 8 one that's been crushed. The post suggesting the over stiff blow off is interesting, maybe I crushed it too much, I might put my crappy plastic oem one back in and see if helps, not holding much hope though.

 

Swapped his MAF with mine and didn't run any differently. For some reason when we started it (before trying my MAF) it sounded like it was literally cammed for the whole time it was running. Restarted it and it went away. It was odd. He recorded a video of it sounding like it is camming out. I think he'll put it up on here soon.

 

That's the thing though, if it was a bad coil pack, wouldn't it break up at WOT? Because it runs great at WOT.

 

Have you done a compression and leakdown test, maybe a burnt valve letting exhaust gas or fuel mixture through when it's meant to be closed or even shot rings.