Any ideas on what might cause a random misfire code? I have 2003 cl-s 6-speed (190,000 miles) and have replaced spark plugs and coils, EGR valve, plenum gasket, throttle body gasket, and power steering pump (It needs a new rack and pinion). It needs a valve adjustment as well, which is what my buddy thinks it is, but I'm thinking of either a crank position sensor or maybe a fuel pump. I love this car but this misfire is making me go insane. Any order in which I should do these repairs if you think it is one of these problems? ANY advice would be greatly appreciated. (yes I should have done the valve adjustment while I was already in there but I was hoping each time the other fix would do the trick and I don't have the expectance to know how much drag there should be).

PS I just bought this car and I am brand new to this website, I accidentally posted this in an old thread, so I figured id make anew thread? Hope that is allowed.

 

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Have you considered the fuel injectors? They might be slightly worn after 190K.

In addition, if it is a six-speed, with an unknown history to you because you just purchased it, also consider bent valves from a possible over-rev situation.

All the threads I've seen here, in the past, when either crank sensor is bad usually the ECM sets a P0336 Crankshaft Position Sensor A, located behind the crank pulley, and Codes P0385,P0386 in regards to Crankshaft Position Sensor B, which is located on the Transmission Bell Housing.

 

I'm gonna take it in a get a valve adjustment and pray the valves are not bent guess. I can hear them clicking so I know it needs to be done regardless. Anyway, how would I go about checking if the fuel injectors are bad? I was thinking it could those as well but the fuel pump is a much cheaper fix lol.

 

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Just in case it was flipped around, make sure the upper plenum metal gasket 'tab' faces toward the firewall when installed and IM EGR passages are clear.