random idle drop
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91beatuphatch
- Posts: 484
- Joined: Wed Aug 18, 2010 1:15 am
random idle drop
im still very lost by this... its showing a 2 wire o2 sensor but i have a one wire o2?
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JustRob
- Posts: 7884
- Joined: Sat Nov 18, 2006 7:28 pm
random idle drop
Sorry, I must have accidentally posted the troubleshooting flowchart from a '92 instead of a '91.
I know you replaced the O2 sensor already, but test it just to be sure it's good. Measure the voltage between the O2 sensor connector (sensor side) and body ground with the vehicle running at operating temperature. Voltage should be above 0.6 V at 4,500 RPM and below 0.4 V when the throttle is quickly released from 4,500 RPM. If the voltage is out of range, the O2 sensor is bad.
If the sensor is good, check the voltage at the ECU between pins A18 (Negative) and C16 (Positive). Same as before, voltage should be above 0.6 V at 4,500 RPM and below 0.4 V when the throttle is quickly released from 4,500 RPM. If not, there is a short in the wire between the ECU and O2 sensor (Pin C16, White).
If it checks out, fuel pressure needs to be checked to see if the fuel pressure regulator is bad. Since you already did this, with the engine idling was the fuel pressure between 41-48 psi with the vacuum line disconnected and pinched from the FPR and 32-39 psi with the vacuum line connected to the FPR? If not, replace the FPR. If it is, then a couple other items could be the culprit. LMK how everything checks out.
I know you replaced the O2 sensor already, but test it just to be sure it's good. Measure the voltage between the O2 sensor connector (sensor side) and body ground with the vehicle running at operating temperature. Voltage should be above 0.6 V at 4,500 RPM and below 0.4 V when the throttle is quickly released from 4,500 RPM. If the voltage is out of range, the O2 sensor is bad.
If the sensor is good, check the voltage at the ECU between pins A18 (Negative) and C16 (Positive). Same as before, voltage should be above 0.6 V at 4,500 RPM and below 0.4 V when the throttle is quickly released from 4,500 RPM. If not, there is a short in the wire between the ECU and O2 sensor (Pin C16, White).
If it checks out, fuel pressure needs to be checked to see if the fuel pressure regulator is bad. Since you already did this, with the engine idling was the fuel pressure between 41-48 psi with the vacuum line disconnected and pinched from the FPR and 32-39 psi with the vacuum line connected to the FPR? If not, replace the FPR. If it is, then a couple other items could be the culprit. LMK how everything checks out.
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( .)(. )Civic
- Posts: 37
- Joined: Sat Jul 09, 2011 5:48 am
random idle drop
I also have this problem but on my y8 does it happen the most right after start up?