Q: 2006 Infiniti M35X...intermittent multiple random misfire(p0300)

asked by on May 16, 2017

2006 Infiniti M35X(223k mileage)... I have an intermittent multiple random misfire p0300 code and p0430(pending) only under high load...loss of power and bad gas mileage.

Here's Freeze frame Data of P0300 (autel al519 scanner) LOAD-PCT(%) 78.8 ECT(F) 82 SHRTFT1(%) 15.6 LONGFT1(%) 9.4 SHRTFT2(%) -1.6 LONGFT2(%) -10.2 RPM 3300 TP(%) 59.6

So, as you can see, there's significant difference between banks. Bank 1 is +25% while bank 2 is -11.8% But at idle, both banks are +7% and pretty stable.

Here's link to my log (torque pro).

http://www.datazap.me/u/hyancan/log-1494095716?log=0&data=14-17-20-27

Bank 1 AFR sensor voltage seems to be mostly stay around 0.35v while bank 2 sensor is 0.5v.

I cleaned MAF sensor. replaced spark plugs, injectors, AFR sensors and vacuum hoses. and swapped coil pack But no changes.

I have been suspicious about catalytic converters or fuel pump. Help me out please...

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Hi there. Thanks for all this data; as it would be very important to have this during an actual onsite inspection. Without inspecting the vehicle onsite, to assume exactly what is causing your poor fuel mileage and acceleration issues would be an educated guess. In regards to helping you here, the best advice I can offer is to have you read this article on the P0430 OBD-II trouble code as it should point out some common causes of this code and possible solutions. Ii is quite possible you are chasing two independent issues; perhaps the fuel pump pick up filter is clogged AND the catalytic converter could be faulty. If we can help you diagnose this at your location, please set up a loss of power inspection by clicking this link.

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