i have done all this before.. that is why i know it is lean.. computer say's left bank lean... plugs are a little white. etc i had a broke ground wire on the left 02.. when i plugged it back up the car mis fireded under a load, when i rebroke the wire its stopped mis firing , but is still a little lean... so being that this is NOT the car i drive to work.. i just want it to run rich as fuel milage is not a problem with it. and it should run better while i trace down other issue's. I know when the computer see's full throttle it goes full rich and this is when the car seems to run at its best, but below that it fill's weaker than it should be. ( one more reason i think its the lean issue on this)
so if there is a wire i can jump or disconnect on the water temp sensor or on the 02 system, to make it think it needs to run full rich than this is the info i need right now
thanks
chad
You are well intentioned, but way off base.
EFI engines are set to run on the lean side to reduce emissions and fuel consumption. Reading the plugs isn't a reliable method of checking the air/fuel mixture unless you shut the engine off when at full throttle, take the engine out of gear and coast to a stop. Then the plugs will reflect what the fuel mixture is and not the lean mixture that is the result of the computer reducing fuel flow to an engine that isn't creating power.
If you got a code 41/91, that is an O2 sensor problem or a vacuum leak. You should see 14.5"-18"of vacuum at 650 RPM, and 18"-21" at 1000 RPM.
Code 41 or 91 - O2 indicates system lean. Look for a vacuum leak or failing O2 sensor.
The computer sees a lean mixture signal coming from the O2 sensors and tries to compensate by adding more fuel. Many times the end result is an engine that runs pig rich and stinks of unburned fuel.
The following is a Quote from Charles O. Probst, Ford fuel Injection & Electronic Engine control:
"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than 400 Millivolts. Remember lean = less voltage.
When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than 600 millivolts. Remember rich = more voltage.
Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.
Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage." End Quote
Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear. The computer pins are 29 (LH O2 with a dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter.
Most of the common multimeters have a resistance scale. Be sure the O2 sensors are disconnected and measure the resistance from the O2 sensor body harness to the pins on the computer.
Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter. Do not attempt to measure the resistance of the O2 sensors, it may damage them.
The O2 sensor ground (orange wire with a ring terminal on it) is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts
Here's a book that will get you started with how the Ford electronic engine control or "computer" works.
Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst :ISBN 0-8376-0301-3.
It's about $20 from Borders.com see http://www.amazon.com/ . Select boo...very good, and I found it to be very helpful.