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View Full Version : L5P: Balance rate criteria changed?



chessy56
08-17-2023, 06:45
2017 L5P, 150K miles
Current DTCs: P026D, P2A00

These are pending codes and have been for quite some time now. I can get anywhere from 10 to 100 "warm-ups without an emissions malfunction" PID count before it gets reset to "0". No recent CEL activation. I've gone through the diagnostics shown in my Mitchell1DIY (which lists the injectors or the NOx1 sensor), as well as checking the fuel rail pressure sensor connector, the fuel filter (and a line flush), all of the various tech bulletins, etc. One individual on another site mentioned that the injector balance rates changed with the introduction of the L5P. According to this guy, GM stated that the old +/- 4 (P/N) and +/-6 (D/R) do not apply to the new injectors used in the L5P.

I'm now hearing that 0 +/- 0.2 is the new criteria and exceeding that contributes to the P026D (but no mention of this being in gear or Park). Yes, I find cyl 4 & 5 occasionally displays 0 +/- 0.4 (or more) and 0.7 on cylinder 2; however, if left to idle for a few minutes after a drive, most of them will settle on 0 +/- 0.2.

Any truth to this new (tight) pass/fail range for the L5P balance rates?
Thanks.

Chessy56

More Power
08-18-2023, 21:04
Hadn't heard about a rate change, but there are potential causes of a balance problem other than injectors... i.e. valve clearances, cylinder compression

cabletech
08-19-2023, 13:30
GM stopped using the Bosch fuel system after the 2016 model year (due to CP4 failures) and switched to a Denso system. That's likely the reason for the change.