Do Bad Balance Rates Mean You Have Bad Injectors?



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  • Do Bad Balance Rates Mean You Have Bad Injectors?

    Today, we're diving into the world of injector balance rates and the burning question: Do balance rates mean you have bad injectors? Well, not necessarily!

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    Let's break it down. Balance rates are influenced by various factors, and it's crucial to consider more than just the numbers you see. Factors like fuel injector health, fuel rail pressure, engine load (think A/C compressor, transmission in drive or park), and engine compression all play a role in determining balance rates.

    So, what's the basic function of balance rates? Essentially, it's a calculated fuel rate by the ECM, adjusting how much fuel each injector needs to maintain equal cylinder contribution and smooth crankshaft rotation.

    Now, when it comes to low compression, brace yourselves for an extremely high balance rate, something like a positive 12mm3 or higher.

    But here's the kicker – balance rates alone won't tell you everything about injector health. Injectors leaking into the combustion chamber can still yield balance rates within factory specs, say +- 4mm3, with a smoking-at-idle condition. What to look for? Check the calculated fuel rate and injector on times. If the calculated fuel rate is 8mm3, but you're seeing a lower rate like 4-5mm3 and injector on times significantly lower or even at 0ms, that's a red flag. Typically, it takes four or more leaking injectors to skew the calculated fuel rate significantly.

    Let's illustrate with an example: All 8 injector balance rates fall within the +4 to -4mm3 range at idle and in park with no accessory load. However, there's smoke in the exhaust. Look at the calculated fuel rate – it shows 5mm3, while the normal rate is 8mm3. That's 3mm3 below normal. Take an injector showing +3mm, add the 3mm3, and you get 6mm3 – over spec. You'll also notice lower injector on times compared to others.

    So, balance rates are just one piece of the puzzle. Keep an eye on the bigger picture to ensure your Duramax is running at its best! Check out the video below if you would rather watch!

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