Fuel Trim Archives - UnderhoodService
Fuel Trims

To gain a better perspective on fuel trims, think about how “analog” vehicles dealt with changing fuel and air mixtures.

Drivability Issues Fuel Trim Diagnostics

No code diagnostics are some of the most challenging drivability issues.

LTF And STF Fuel Trim Feedback Loops

How to understand rich, lean and somewhere in between.

Air Filter And Fuel Trim Diagnostics

The modern engine measures two things extremely well, the amount of air going into the combustion chamber with the mass airflow sensor (MAF), and the byproducts that are generated by the combustion event with the oxygen sensor. These measurements allow the engine’s computer to put the right amount of fuel and spark into the cylinder to give the most efficient and cleanest combustion event.

Fuel Trim Theory And Operation

The modern engine measures two things extremely well, the amount of air going into the combustion chamber with the mass airflow (MAF) sensor, and the byproducts that are generated by the combustion event with the oxygen sensor. These measurements allow the engine’s computer to put the right amount of fuel and spark into the cylinder to give the most efficient and cleanest combustion event.