Hi all,

I have a 2008 Sport MT with around 230,000 miles (370,000KM). I've recently done a valve adjustment and replaced all ignition coils - which fixed the issues I was having with the engine stalling when cold and it stuttering in 4th and 5th gear. The exhaust valves had little to no clearance on all of them and I adjusted to around .011. Intake valves were slightly loose and I adjusted to around .007. Engine looked surprisingly clean inside.

This was done around 2 weeks ago and I've probably driven ~1000 miles since. The car feels new again and I'm getting a slight increase in MPG, but I've developed a P0497 and P0420 code as of yesterday. I'm not sure if it's related to something I did via the valve adjustment, but the timing seems suspicious. I also had the idler pulley and serpentine belt replaced around 5 days ago due to the idler pulley bearing going out and spinning freely. The new belt seems tight and all accessories are working.

This car does have a history of evap issues and had developed a misfire previously where it fouled out the cylinder 3 spark plug and ignition coil. This was taken care of probably 30,000 miles ago, but maybe it damaged the catalytic converter and is just now presenting itself? My back O2 sensor seems to be all over the place. Screenshot below is around 2900RPMs and the gridlines represent 5 second intervals. Additionally, I'm noticing a slight knock sound that seems new - most audible between 0:04-0:06 here: I don't recall ever hearing this before the idler pulley replacement.

Any advice on next steps? I'm thinking I may try changing out the PCV valve and see if that resolves anything. I don't have to get emissions checks, so I can get a cheaper catalytic converter if necessary. And now that I'm fully paranoid I may recheck valve clearances this weekend to make sure they're in spec.

 

On your scanner look on catalyst temperature during cruise speed - post it here so we can compare it to the readings I took 6 years ago (when my car was newer)
The evap issues can be caused caused by collapsed or plugged hose between pure valve and intake plenum or purge valve itself (fails to open)
New noise after belt change can point to the belt vibration, loose valve gives ticking every other engine revolution (diesel like sound at idle, almost like leaking spark plug or exhaust gasket) but it is more like ticking type of sound

 

If I recall correctly the catalyst was reading around 1100F via the scan tool. I tried using an IR thermometer and that indicated around 450F towards the front of the catalytic converter and around 400F at the back.

I went ahead and took it into a shop to have them take a further look. They mentioned they have a new exhaust tool that can test the catalytic converter. I'm fully expecting it to get replaced, but my concern is what would have killed it - maybe just age since it's 230K miles?

Another thing I mentioned to them was crankcase pressure. Quite a bit of air escapes out the oil fill cap if the engine is idling. I'm hoping it's PCV valve related and not piston rings, like they suspected when I mentioned it.

Hoping to hear back from them in a few days and I'll be sure to update here.

Thanks for the help!

 

Do you have any oil in intake?