If you are using OBDII scan data you will notice a pid called Absolute Load Value. This is an indicator of the engine's current pumping response based on the demand and presented as a percentage. Think of this as a "Lung Capacity" test for your car. It shows how much air your engine is actually pulling in compared to the maximum amount it was designed to handle. For example, if this value is at 80% it means your engine is filling its cylinders 80% of the way with fresh air. It's a great way to see if your engine is breathing well or if there is a problem causing it to struggle for breath. Calculated Engine Load is what the computer is trying to do under current conditions, like giving 100% to sprint up that steep hill (wide open throttle for instance). A comparison of the two data items can help determine if you have a breathing problem and what may be the cause. If you are looking for the cause of your car struggling up a hill or losing power on hard acceleration, and you see 100% Calculated Engine Load but a Absolute Load Value much lower then you have a problem with lung capacity. At a Calculated Load of 100% you want to see 85% or better Absolute Load. 70% to 80% is a red flag and anything less than 70% you definitely have a restriction in intake or exhaust. Now there are other causes for power loss at wide open throttle, fuel delivery for instance, but a weak fuel delivery won't show up in your Load Values. You look for hints of that in fuel trims or by looking at air/fuel ratio sensor data during the problem. In Load Values if you see both Absolute and Calculated low at wide open throttle during the power loss you likely have a Mass Airflow sensor problem. We'll cover those topics later.
"If your car has a turbocharger, don't be alarmed if your Absolute Load goes over 100%! A turbo literally force-feeds your engine, so it can actually breathe at 150% or even 200% capacity."
Thanks for reading!
Kenny@GGAuto.Repair
No comments:
Post a Comment