Philml

Rebuild coil packs (forgot the name who did it, will find out if important) suppose to be bulletproof for renntech, about year after filled up with fuel (haven't got into a boost that whole day) about 2 minutes later it started to missfire slowly and literally minute it started missfire it went full blast missfire, later on checked the codes and it was 8 cylinders missfire plus o2 sensor code , is there any chance it could me sparkplugs?
Any help would be appreciated greatly

JJKCMO

Voltage transformer?

Philml

I sent it to v12icpack to test it and it tested good

Philml

Could the low voltage main battery possibly cause missfire? Month after it happened the main was pretty much totally dead, couldn't test it after I charged it since voltage transformer was out to be tested

ItalianJoe1

Not usually, did you replace the battery though? You say 8 cylinders went down, was that all 6 on one side and 2 others, or spread around? Does it still misfire on the whole bank after starting?

Philml

I charged it and it was 100% and missfire was on
​​​​​5 8 9 10 4 12 11 6 cylinders if the battery gives me any sign of a problem I will replace it

Philml

waiting for the voltage transformer to return so I can test it more and it seems like it was half of the passenger side and all but one driver side cylinders that missfired

ItalianJoe1

Check fuel pressures, I've seen a few older M275 cars with weak pumps, if you lose a transformer or coil pack it should be every cylinder on that side, but it's always possible a few on the other side pop up randomly. I'm fighting an issue where my whole right bank goes down, used to do it only under heavy load, now it's right on startup. Pretty sure my ME is dead, as i've swapped coils and tested the voltage transformer as well.