Currently have a 2005 S2000 with 125k miles. Just replaced the head with all new 16 valves and guides as well with valve seals. The head was sent to a reputable machine shop. Two days later having a check engine light for 3 cylinder misfires (1,3,4). Also a knock sensor code. I’ve done new NGK spark plugs and OEM coil packs as well. The car does bog a bit when driving and has some trouble starting. It will crank over and eventually start if I give it a little gas in the pedal. Anyone have any ideas on how to get this issue fixed? Thanks

 

Since the car was recently fixed, maybe you should ask that shop to help with the diagnosis.

Out of curiosity, why did the engine need a complete head job?

Thanks!

 

It needed a head job because the exhaust valves were leaking and the car had really low compression.

 

Sounds like either the machine shop fudged something, or whoever reassembled the engine fudged something. I'd start with checking the valve lash. It could just need a valve adjustment.

 

I would not touch anything before taking it back to the shop that did the work and giving them a chance to look into it. Even if it is a good shop and they would cover their stuff, they are much likely to do so once you have started messing with things. Easy for them to then claim you caused the issue. So, take that list of codes with you and give them a chance to look at it.

Did they also assemble everything or did you just have them do the head work?