I have a 2006 Honda S2000 with a P0420, P0300, P0302, P0303, and P0304 code. The car has an intake, Invidia Catback, and is tuned on KTuner. It appears the previous owner drilled the cat out and welded it back on. I’ve replaced plugs, coils, injectors, fuel rail, fuel pressure is good, and cleaned the MAF. The car idles fine on cold start in the mornings and doesn’t misfire. Once the cars warm it starts to misfire. Could a bad upstream o2 cause these issues?

 

Got a spacer on the secondary sensor ?

 

I do, found out my timing is off while working on it today. Would you know how to adjust the timing?

 

Cam or ignition ?

 

P0420 is no surprise since you don't have a catalytic converter but plenty of guys admit to "test pipes" and there are ways to spoof even the earlier non-tuneable OEM ECUs. Your tuner is the key guy here. Same for timing. My Gernby FlashPro tuned 2006 shows none of these symptoms but does have a Berk 63mm high-flow cat. One of these is inexpensive will bolt right in and may be all you need on that side.

I'm guessing passing smog is not an issue (we have no idea where your car is registered)?

-- Chuck

 

My cans are misaligned when the crank is at TDC

 

the car is registered in KY so smog isn’t an issue for me. I’ve attached photos of the crank and cams, is this off or normal?

 

A good way is to test for tdc of piston <remove spark plug ect> and check there.
crank pulley can have some movement wear as its rubber