Even number cylinders all misfire at the same time only under load?
What is your question?
My entire right bank of cylinders misfires at any temperature but only under load of 40% or more, when the engine is accelerated in neutral there is never a misfire. I replaced fuel pump, injectors, coils, plugs, wires, VVT actuator and solenoid, cam and crank sensor, timing chain and vvt sprocket. I used all OEM parts. O2 sensors are reading good and the catalytic converters are good. the engine is healthy with 180 psi compression in all cylinders with a 5% variance. Still the same problem after replacing all that (some of the repairs were due to other problems) the vehicle is barely drivable as is. I have a good scan tool and have been able to analyze all the data but to no avail? NEED HELP. Thanks
What makes this problem better or worse?
only under load
How long has your 2007 GMC Yukon had this problem?
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I’m retired - no longer need to keep up with em!
Can switch 02 sensor with B1 to see if problem follows the sensor.
You stated 02 sensors are reading good - based on what? .... Is the front B2 02 sensor actually reading within ‘specifications’ during test drive - are fuel trims within specifications ?
It is impossible to post scan tool live data readings in a way another technician can decipher them as if it were actually being viewed by the tech *hands-on*.. There’s simply too many observations that need to be made during a scan test.
Good luck!
There are a number of potential causes for your concern. However, the active fuel management (AFM) system is a common problem with these engines. There are several TSBs for the issue.
The AFM system deactivates four of the engine's cylinders (cylinders 1 and 7 on the left bank; 4 and 6 on the right bank) under certain light load conditions. The system relies on a valve lifter oil manifold assembly (VLOM) with integrated solenoids, a relief valve and unique AFM lifters. Although the problem can be anywhere within this system, I often see collapsed AFM lifters.
Now, I'm not saying this is your problem for sure (since I haven't looked at the vehicle) but it's something to consider. To get a definitive answer, you will need to have the vehicle inspected firsthand by a professional. A list of reputable shops can be found here: https://repairpal.com/repair-shops
Also, here is some more information on the AFM issue: https://www.autoserviceprofessional.com/article/91652/ticking-gm-v8-lifters-and-dtc
I’m retired - no longer need to keep up with em! Can switch 02 sensor with B1 to see if problem follows the sensor. You stated 02 sensors are reading good - based on what? .... Is the front B2 02 sensor actually reading within ‘specifications’ during test drive - are fuel trims within specifications ? It is impossible to post scan tool live data readings in a way another technician can decipher them as if it were actually being viewed by the tech *hands-on*.. There’s simply too many observations that need to be made during a scan test. Good luck!
I knew I had seen this information in a TSB some years back: https://www.justanswer.com/chevy/59kyw-consistant-miss-fires-2-4-6-8.html