Trying to figure out why a friends 04 i35 had a miss on cylinder 2.? He said he was driving to work and check engine light came on then soon after the car started missing. Changed plugs, and coils still missing. Any advice guys?

 

OEM spec spark plugs and coilpacks? It's likely a failing injector. Luckily cylinder 2 is easy to get to. What was the engine code when the codes were pulled?

 

Code 0302 cylinder 2 misfire. I changed the injector still misfiring

 

Used, rebuilt or new? Don't rule out that the new injector is still faulty. I once had a misfire, replace the injector with a refurbished one and "flow tested" only to have ongoing misfire issues. Replaced the injector again, and the misfire went away.

It can only be 3 things. Spark plug, coilpack, or injector. Swap Coilpack 2 with coilpack 4 and see if the code moves to cylinder 4. If so, it's your coilpack and not your injector.

 

Owner bought new aftermarket coils. I’m going to swap coil packs tomorrow and see. Also I’m going to pull spark plugs. I don’t know what else to test for besides compression

 

Also injectors are reman and tested

 

Oh boy, our cars are picky and seem to only like OEM spec coilpacks. Let's see what happens when you swap coilpacks. Pull the sparkplug and check for condition, and for crap stuck at electrode.

 

Like I said, don't rule out that the "new" injector could be bad.

 

Ok thanks I’ll swap coils and see what happens

 

 

The plug from cylinder 2 is clean and other plugs look slightly worn. What isn’t cylinder 2 getting correctly

 

Yeah, but you just recently changed the spark plug in cylinder 2. Were any miles put on the car since the replacement?

 

Also, here is a good chart for reading spark plugs.

https://ngksparkplugs.com/en/resources/read-spark-plug

 

Found the issue someone replaced the coil harness with an aftermarket one. I’m going to cut a factory one off and replace it. Also remove intake and replace injectors and plugs with OEM coils and ngk plugs. Owner had Bosch in there smdh

 

Nice detective work.

I was gonna say, wha'ts with the Bosch plugs? NGK all the way.

 

Yes what kind should I go with for best performance and i appreciate the help

 

VQ engines work best with OEM plugs (NGK)