MAF G/Sec Open Loop Higher Than Closed Loop?
Thread Starter
TECH Fanatic
Joined: Jan 2022
Posts: 1,362
Likes: 256
MAF G/Sec Open Loop Higher Than Closed Loop? Newbie question here but are the MAF grams per second supposed to be higher in open loop than they are in closed loop? On a cold start mine was reading 11.78 g/sec at idle and after it was in closed loop it got down into the eights. I shut it off a little bit and then went back to check it again. This time the motor was warm and the MAF reading was in the sixes. Is from an 11 to a 6 the normal open loop to closed loop range for a stock ls1 with the stock tune? I’m assuming it’s higher in open loop due to the higher idle speed. Is this correct? Or is that too big of a spread?
While I’m here I’d also like to ask, is a 0.39% TPS reading at idle normal?
While I’m here I’d also like to ask, is a 0.39% TPS reading at idle normal?
TECH Fanatic
Joined: Jan 2018
Posts: 1,059
Likes: 198
It's normal, but open-loop / closed-loop is not what's causing it. As the car gets warmer, the the idle RPM goes down, the oil gets thinner, the spark advances, and the mixture goes from rich to stoich.
All of those help it idle with less airflow. When the AFR reaches stoich the car goes into closed-loop but that's a side-effect, not a cause.
My current and previous engines needed roughly twice as much air for a cold start as for warm idle so it sounds about right to me. So does the throttle position.
All of those help it idle with less airflow. When the AFR reaches stoich the car goes into closed-loop but that's a side-effect, not a cause.
My current and previous engines needed roughly twice as much air for a cold start as for warm idle so it sounds about right to me. So does the throttle position.
Thread Starter
TECH Fanatic
Joined: Jan 2022
Posts: 1,362
Likes: 256
It's normal, but open-loop / closed-loop is not what's causing it. As the car gets warmer, the the idle RPM goes down, the oil gets thinner, the spark advances, and the mixture goes from rich to stoich.
All of those help it idle with less airflow. When the AFR reaches stoich the car goes into closed-loop but that's a side-effect, not a cause.
My current and previous engines needed roughly twice as much air for a cold start as for warm idle so it sounds about right to me. So does the throttle position.
All of those help it idle with less airflow. When the AFR reaches stoich the car goes into closed-loop but that's a side-effect, not a cause.
My current and previous engines needed roughly twice as much air for a cold start as for warm idle so it sounds about right to me. So does the throttle position.
