Fuel system status
#1
04-09-2016
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Location: Edmond, OK
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Fuel system status
I have a 2005 ford ranger 3.0l v6 I just recently bought a scan tool and my fuel system status is open loop due to system failure when bogging down and closed loop using oxygen sensor to determine fuel mix when not bogging down what does all this mean I have p0305 misfire detected on cylinder 5 and it does seem to switch between the two even when the truck has warmed up
Last edited by Lotsofcoolify; 04-10-2016 at 05:11 AM.
#2
04-09-2016
The OBD2 system uses code numbers, hundreds of them, PARTIAL list is here: OBD-II Trouble Codes
These are in "Computerese" not "english", after all it is a computer that is using them, and a very very dumb computer by today's standards.
The scan tool is not any smarter, so grain of salt when interpreting codes
You need to post the code numbers associated with what you are saying.
"Open Loop" means the computer can't rely on a sensor so it using preset tables in memory to run the engine.
Open Loop is normal on a cold engine, O2 sensors don't working until they are above 650 degrees, and a cold engine needs a richer fuel mix and higher idle(choked) to run right, so computer has to wait until they warm up.
Computer will then go to Closed Loop, and use all the sensors to run the engine more efficiently.
If computer has trouble with a sensor's data coming in it may switch to Open Loop again even after warm up.
If a sensor's data is high or low or isn't coming in the computer sets a code for that, and that usually means the sensor IS WORKING, the code is there because there is a problem with the system that sensor is monitoring.
So "don't shoot the messenger", if a code description mentions a sensor then that sensor is NOT the problem, computerese.
Fuel system doesn't have open or closed loop
The computer will turn fuel pump on and off based on engine/driver demand for fuel.
There is a fuel tank pressure sensor, but that's part of the EVAP system and would effect engine operation
4.0l SOHC did have a pressure sensor on the fuel rail, 3.0l didn't as far as I know.
If you engine is bogging down then clean the MAF sensor.
Get a Vacuum gauge($25) and test for steady 18"-21" of vacuum at idle, pop open throttle a few times and watch what vacuum gauge does.
And post the codes
These are in "Computerese" not "english", after all it is a computer that is using them, and a very very dumb computer by today's standards.
The scan tool is not any smarter, so grain of salt when interpreting codes
You need to post the code numbers associated with what you are saying.
"Open Loop" means the computer can't rely on a sensor so it using preset tables in memory to run the engine.
Open Loop is normal on a cold engine, O2 sensors don't working until they are above 650 degrees, and a cold engine needs a richer fuel mix and higher idle(choked) to run right, so computer has to wait until they warm up.
Computer will then go to Closed Loop, and use all the sensors to run the engine more efficiently.
If computer has trouble with a sensor's data coming in it may switch to Open Loop again even after warm up.
If a sensor's data is high or low or isn't coming in the computer sets a code for that, and that usually means the sensor IS WORKING, the code is there because there is a problem with the system that sensor is monitoring.
So "don't shoot the messenger", if a code description mentions a sensor then that sensor is NOT the problem, computerese.
Fuel system doesn't have open or closed loop
The computer will turn fuel pump on and off based on engine/driver demand for fuel.
There is a fuel tank pressure sensor, but that's part of the EVAP system and would effect engine operation
4.0l SOHC did have a pressure sensor on the fuel rail, 3.0l didn't as far as I know.
If you engine is bogging down then clean the MAF sensor.
Get a Vacuum gauge($25) and test for steady 18"-21" of vacuum at idle, pop open throttle a few times and watch what vacuum gauge does.
And post the codes
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