emissions failure update

With no cats, you will fail the visual part of the inspection. Your chances of passing without them on and properly functioning are not good, especially on a car that is still running the original engine with lots of miles on it.

The thermactor air system is the smog pump and control valves. You will post codes 44 & 94 if the solenoid control valves are missing or not connected.

if the check engine light doesn't come on (which i doubt it does) then who cares? they dont do OBDII tests on anything below 1998 i believe or 96. throw ur cats on and go


edit: if it's the actual pump not pumping air, then replace the smog pump. with the car on, remove the hose from the smog pump and check if it's pushing air.

***BE CAREFUL OF THE BELTS***

ttop5oh said:

well, they didn't do a visual inspection, WA is pretty good about not doing that...i have never had them do one on anything i have e-tested...what i am curious about is CAN it pass the computer test without them? the motor is mostly stock and only has about 60k miles on it. as far as the solenoids, they are hooked up and i assume they are functioning...i just have code 91-Thermactor pump inop...all other codes are fixed...

Josh

Click to expand...

Codes 44/94 are the Thermactor Air System codes. Code 91 is an O2 sensor.

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

You may be out of luck to pass smog without the cats. I doubt it can burn clean enough but what you can do is try an msd ignition and try to run it lean.
Kevin