I am assuming I messed up when I installed my passenger side catch can this weekend... Car was running fine other than an "unmetered Air" code which is one of the reasons I installed the passenger side catch can. Now under medium to heavy acceleration the car starts misfiring bad. The code is misfire on cylinder 4 and misfire on all cylinders. When it first happened I pulled over and the car was running on 3 cylinders with number 4 not firing at all. I swapped coils and 4 was still not firing. I cut the car off and when I restarted it, all cylinders were running... I went and drove it again and the same thing happened again so I cut the car off then started again and all cylinders firing. I went back to the house and took the catch can off and put the plastic pipe back on that runs from the valve cover to the intake manifold. I went and drove the car again and same thing happened but this time I cleared the codes with my scanner while car was running and the 4th cylinder started firing again. Not sure if I could have messed up a wire or injector when I was snaking the pipe through the manifold or what. Everything looks to be connected and I don't see any broken wires but it is tough to see much under the manifold. Any Ideas?

 

Your "unmetered air" could be caused by an OCC drain (valve or hole) being left open, and the manifold is getting air through it. Shouldn't cause a misfire tho --- can't help with that one. Try resetting the ECU in addition to clearing codes.

 

Consider getting your intake walnut blasted. Cleared up my misfires and the renewed power feels great. 3 hours labor at your dealer.