01blkt/a

Ok new to the ls1 motor recently did the mac mid lengths and off road y and a lid. I of course did plugs and wires when i did the headers cause i was there, went with the msd wires an ngk plugs now i am getting a random misfire code so i put it on my snap on scanner its mis firing only on bank 2. Im out of ideaschecked everything seems fine just has a random miss. Know i need to get a tune but waiting for gears an cam. Will a tune cause this or any ideas of what may be doing thi. Thanks in advance.

SouthernRex

I've heard things about "performance spark plugs" not working right in the LT1 and LS1 motors, but I don't want to just throw ideas out. There are people with a lot more expertise on here than me.

alfablue

Just have to remember that an engine needs three things to run:

Proper Fuel/air mixture
compression
spark

We can safely assume you have compression unless something went horribly wrong with the header install.

Fuel/air can be changed by the headers. The o2 sensor does get moved further down the stream and that will affect how it reads. I don't think this would be enough to cause a misfire issue, but I could be wrong. Did you replace/check the o2 sensor when you did the install? How old is it? I had an issue with my o2 when I first got mine that was causing a misfire issue, but that was with stock exhaust. (You could test the injectors and the signal with a tester and noid light if you wanted)

Lastly spark, What NGK plugs did you get? What are they gapped at?

Best way to figure some of this out is if you have some kind of OBD2 reader (not just a scan tool because that wont really tell you what the sensors are reading) and see what the o2 sensor says on the pass side. Is it just sitting low and staying low? High?

01blkt/a

Think i figured it out my buddy was helping me and think he swapped the o2s front to back i swapped them an runs fine now and no misfires reading on my snap on scanner thanks for all the help.