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-   -   Need help interpreting these. Codes are cul 5 misfire and banks 1 n 2 o2 sensor bad (https://blazerforum.com/forum/engine-transmission-35/need-help-interpreting-these-codes-cul-5-misfire-banks-1-n-2-o2-sensor-bad-105097/)

GeorgeLG 10-28-2022 01:57 PM

This data is a mix of no load in park and driving which makes it harder to draw conclusions, especially fuel trims. That said, I know that you are facing challenges and very busy so I will give you my thoughts on what I see. Difficult problems like this are tough to solve this way without ongoing dialogue.

You have a #5 cylinder problem that should be repaired. Some vehicles can run OK with a bad cylinder but other problems may follow like destroying the cat. I would want to verify with a retest, throttle open, all plugs out, engine warm not hot. Also looking at the plugs.

Your fuel trims are vastly different between banks, even going from heavily rich to heavily lean, but because you are driving for the 2500 test I cant get too specific. The fact that the banks are so different says that the problem is not likely global in nature (affecting all cylinders equally) so probably not say the MAF or ECT. I would swap pre cat sensors and see if the mismatch follows to rule out sensor problems. Test right before and after. One of the cheapest things to rule out are exhaust and intake leaks since at times you are compensating for a severe lean condition. Other things that can cause this severe fuel delivery mismatch between banks are injectors and there are injector delivery tests to help with that. You can also test the firing pulses for the injectors

There are other Android apps that can do some of the things that we like to look at here like CMPR and O2 sensor graphs. They run about $10 a pop and Torque Pro and Car Diagnostic Pro would cover it. We usually use the Amazon BAFX BT dongle for around $25. I don't know if yours will work but I think Torque lite is free and would at least tell you if you can connect OK.


George


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