Envision Engine Running Lean: Power Loss & Jerking

I dealt with nearly identical symptoms on my 2018 Enclave last year, and as someone with some hands-on experience maintaining cars, these signs immediately raised concerns about fuel delivery. After monitoring the rough running and jerking during acceleration, I took it to my regular workshop. The diagnostic scan revealed a faulty fuel injector was disrupting the air-fuel ratio, causing incomplete combustion. The mass air flow sensor readings were normal, but the engine was getting inconsistent fuel delivery. The repair involved: Testing all fuel injectors, Replacing one defective injector, Cleaning the throttle body while they were working in that area, Full system diagnostic after repair Total cost came to 515 Euro for parts and labor. Since the repair, the engine has run smoothly with proper power delivery and no check engine light. However, different model years can have varying issues. Could you share: Current mileage on your Envision, Any recent maintenance history, Whether the check engine light appeared suddenly or gradually, If the symptoms are worse during cold starts or when the engine is warm This information would help determine if your situation matches what I experienced or might point to a different underlying cause.

Thanks for sharing your experience. Just had my car serviced at 118949 KM and started noticing these issues shortly after. The scan from my mechanic pointed to both upstream oxygen sensors giving inconsistent readings. This explains the air-fuel ratio issues and why the check engine light keeps coming on. They also found carbon buildup around the spark plugs, likely contributing to the rough running. Getting it back in the shop next week to have the O2 sensors replaced and spark plugs cleaned. Really hoping this resolves both the power loss and engine roughness. Will keep the group updated on whether this fixes all the symptoms.

Thanks for the update on your Envision. When I had my Enclave serviced, the oxygen sensor readings were also part of what we checked, but in my case, the fuel injector was the main culprit behind the air-fuel ratio issues. The carbon buildup you mentioned around the spark plugs often happens when the engine runs too lean for an extended period. This matches with those inconsistent O2 sensor readings you mentioned. The intake manifold and throttle body might also need inspection since carbon deposits tend to spread throughout the system. After my fuel injector replacement, I made sure to use high-quality fuel and fuel system cleaner every few months to prevent future issues. This maintenance routine has kept my engine running smoothly with no check engine light returns. Do let us know how the O2 sensor replacement works out. If you still notice any rough running afterward, it might be worth having the fuel injectors tested as a next step, considering how similar our symptoms were.

Most of the O2 sensors have been replaced now and I wanted to follow up on the results. The check engine light finally cleared and the engine is running much smoother during acceleration. The mechanic also did a thorough cleaning of the throttle body while they were working on it. The air-fuel ratio seems to be properly regulated now based on how the engine performs. No more jerking or power loss issues. Total repair cost was around 800 for parts and labor, but worth it to have the engine running correctly again. The only lingering item is they recommended having the mass air flow sensor cleaned at the next service interval as a preventive measure. But for now, all the major symptoms that initially concerned me are resolved. Really appreciate everyone who provided input on troubleshooting these issues.