I've been working on my Q45 for the last year or so when time allowed - new timing chain guides & tensioners, new lifters, new NGK Laser Platinum plugs, reman 93-96 style injectors from AUS Injection, later-style fuel rails, new fuel filter, new OEM air and coolant hoses under the plenum, new OEM knock sensors, new OEM radiator hoses and heater hoses, new OEM water pump, new OEM thermostat & radiator caps, and new gaskets and seals for everything that was removed. I finally got it all reassembled on Saturday and was rewarded with a misfire - feels like 1 cylinder. I tested all the coils while it was apart and they were all within the factory spec for resistance. There is no check engine light on.
At this point I'm guessing it's either a bad coil or a COP boot that's causing the misfire, but the only way I can think of to test them is pull each one out individually, stick a plug in the end, and visually see if there's a spark. Does anyone have any suggestions on a better way to diagnose which cylinder is misfiring and what component is causing the issue?
Last edited by Ryantzer
on Mon Jun 28, 2021 12:34 pm, edited 1 time in total.