Air / Fuel Levels
03-27-2005, 03:27 AM
#1
Racer
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Air / Fuel Levels
What would be a normal A/F reading at idle for an 84 944. I had my car dyno'd with A/F and the reading was 40:1. Everyone in the garage was amazed. They said most car's won't even run past 20:1.
03-27-2005, 12:38 PM
#3
Three Wheelin'
Your engine should be running somewhere near 14.5:1 at idle. The fuel/air ratio is controlled by the DME based on engine coolant temperature, air flow, and excess O2 levels in the exhaust.
The primary control is the O2 sensor, which developes an output voltage that is roughly proportional to the amouint of excess O2 in the exhaust.
The easiest way to check the O2 sensor is to tap into the sensor wire with a digital volt meter. At idle the sensor should have an output that varies across 0.50 volts. A second test is to disconnect the O2 sensor from the DME and read the sensor's output. In this configuration the sensor should have an steady output of between 0.50 and 0.70 volts DC.
The primary control is the O2 sensor, which developes an output voltage that is roughly proportional to the amouint of excess O2 in the exhaust.
The easiest way to check the O2 sensor is to tap into the sensor wire with a digital volt meter. At idle the sensor should have an output that varies across 0.50 volts. A second test is to disconnect the O2 sensor from the DME and read the sensor's output. In this configuration the sensor should have an steady output of between 0.50 and 0.70 volts DC.
03-27-2005, 02:53 PM
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Originally Posted by Charlotte944
Your engine should be running somewhere near 14.5:1 at idle. The fuel/air ratio is controlled by the DME based on engine coolant temperature, air flow, and excess O2 levels in the exhaust.
The primary control is the O2 sensor, which developes an output voltage that is roughly proportional to the amouint of excess O2 in the exhaust.
The easiest way to check the O2 sensor is to tap into the sensor wire with a digital volt meter. At idle the sensor should have an output that varies across 0.50 volts. A second test is to disconnect the O2 sensor from the DME and read the sensor's output. In this configuration the sensor should have an steady output of between 0.50 and 0.70 volts DC.
The primary control is the O2 sensor, which developes an output voltage that is roughly proportional to the amouint of excess O2 in the exhaust.
The easiest way to check the O2 sensor is to tap into the sensor wire with a digital volt meter. At idle the sensor should have an output that varies across 0.50 volts. A second test is to disconnect the O2 sensor from the DME and read the sensor's output. In this configuration the sensor should have an steady output of between 0.50 and 0.70 volts DC.
I did notice under hard accelaration it went down to 13:1. I just want to have my car running well and have it pass smog too.