2007 M35x Ignition Coil Wiring

[RemtechM35x]

Hey Guys,

First off I bought this car used at about 40K miles so there is some history behind this vehicle with another owner.

After my first spark plug replacement Ive always wondered if they wiring on my ignition coils were in the correct order. I matched it every time by marking them before i remove the plugs. It just bothered me that on the driver side the furthest back and the middle harness plugs sorta looked flip flopped. Reason why I thought this is because aren't they usually in order by length? The furthest back coil is plugged in the middle plug on the harness and the middle coil is plugged into the plug that is the shortest which is the furthest back plug on the harness.

Also the cats burnt out at about 80K miles which I thought that was a bit too early. In the back of my head it seems like I am shooting unspent fuel down there. On idle it is smooth but it putts here and there occasionally. Not consistently.

Could someone take a picture or provide me with a schematics for this harness please?

[psyopper]

The length of the wire doesn't matter, it's just a connection between the distributor/coil/harness and the spark plug. If these were installed incorrectly neither of your cylinders would be firing and you would know it as the car would be nearly un-drivable.

You can swap these cables between cylinders to better match the length, what matters is connecting the correct output on the harness to the correct input on the engine. More than likely the PO didn't reinstall them correctly. Strange that you've done more than one plug change, plugs on this car usually go 100k between changes.

Maybe one of the photos here will help> howto-change-spark-plugs-m35-vq35de-t497801.html

[lovemycarM35]

I had the same issue with my M I few weeks ago it would stutter but only at certain positions of the throttle occasionally. Not consistently this also happening to a another member on the forum. It turned out to bea bad ignition coil so I replaced all six of them OEM and plugs by the way my M only has 74K and my plugs were not good according to my mechanic. cars smooth as butter now no more stutter