Suburban Engine Runs Lean

I own a Chevrolet Suburban as well. Your experience sounds familiar. Lean running, power loss, and the check engine light. Before you replace the injectors, have you thought about other things that affect the air-fuel ratio? What diagnostic codes are you getting? Have you checked the EGR valve or the intake manifold for leaks? A bad catalytic converter could also make the sensors think it's running lean.

Thanks for the reply. I got a P0171 code, for a lean condition on Bank 1. I haven't checked the EGR valve or intake manifold for leaks yet, but I will. How could a faulty catalytic converter affect the readings?

Think of the catalytic converter as the engine's respiratory system. If it's not 'breathing' correctly, it can skew the oxygen sensor readings. These sensors control how much fuel the engine gets. A failing converter might not process exhaust gases well, making the sensors misinterpret the data and tell the engine to run leaner than it should. Given the P0171 code, I'd suggest seeing a qualified technician for a full diagnostic. It is better to be safe than sorry, before catalytic converter damage follows which is going to be extremely expensive.

Thanks for the guidance and explanations. It makes sense, and I agree a professional diagnostic is a good idea. I took the car to the workshop. Eventually the mechanics changed the fuel injectors. The final repair cost was 515€. Thanks again for your help.