Field Trip! Misfire Diagnosis Pt.2

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  • Hello Matt,
    I was wondering if there could be performance problems that do not trigger a code.

    I thought a while and decided to trust PCMs more than I should have. BECAUSE I later found on your youtube channel a video from 2012 where test driving could not regenerate a previously generated code. (The car was misfiring on bank 1). The problem was an oxygen sensor. In the video you confirmed it was not a wiring or PCM problem.

    From this I am concluding that it is possible for a functioning PCM not to throw codes for performance problems that are obvious (misfiring) to the driver/mechanic. This leads me to question if less obvious performance problems which “authorized service centers’ say DO NOT EXIST can and/or do exist.

    Some time ago I watch a video where you explained the “cells” of a PCM in relation to fuel trim data ( I believe). I would like to a have a better understanding of PCMs. I am thinking that PCMs mapped for France by the manufacturer which some how end up on the market in Turkey perform poorly in Turkey. However, “dealerships” are saying “NO PROBLEM – it is in your head”.

    Can you direct me to a source that explains PCMs in a helpful manner?

    Thanks a lot for your labors and generosity to us.