So, today I had an older model Camaro, 2001, high mileage, and not very well maintained. It came in with the check engine light on, and had codes stored for the fuel trim being lean. Specifically, a P0174 Fuel Trim Lean Bank 2 code. This was surprising as while watching the info on the Tech 2 scanner, both banks seemed equally lean. Usually, lean codes result from the engine getting too much air in the air/fuel mixture.
After all the basic checks for vacuum leaks, making sure the oxygen sensors were working correctly, and no other parts were broken, it was looking like it might be a difficult fix. There seemed to be a lazy oxygen sensor in position number two, but it did come back to normal as I continued diagnosis. So, a little deeper into this I went. I decided to take a fuel sample and check alcohol content to see if that was the cause of the lean condition. It checked out at 11 percent, which is acceptable. Fuel pressure was also fine at around 55 psi.
Basically it came down to the idea that the car wasn’t getting enough fuel delivered through the fuel injectors. The car’s computer is telling the fuel injectors to spray a certain amount of fuel for a certain amount of time. When clogged up or dirty, the injectors can only flow a minimal amount. The computer is expecting to see a certain air/fuel ratio, and when they can’t flow, there will be more air than fuel and become lean in the cylinder. This can happen due to the fuel injectors getting clogged from poor quality fuel, additives, etc.
Fuel Injector Cleaning
A fuel injector cleaning, as well as inspecting and cleaning the air intake system and mass airflow sensor did the trick! The fuel trim levels were back at a near perfect level on this Camaro. So, if you ever have a problem where the usual things aren’t checking out, don’t give up and just dig a little deeper. The problem will usually present itself with enough looking!