95 2.0 FWD FCC PCM Equipped Vehicles

1995 2.0L FWD FCC PCM Equipped Vehicles

Upstream O2S Monitor
Engine at normal operation temperature above 170°F. Operate the vehicle for a period of time, more than 2 minutes, at a speed above 25 mph. Bring the vehicle to a complete stop, foot on the brake transaxle in gear (automatic transaxle) neutral for manual transaxle. The monitor should run while vehicle is stopped with the engine idling. Wait for a few minutes to allow the monitor to complete before turning off engine.

Downstream O2S Monitor
Engine at normal operation temperature above 170°F. Decel Fuel Shut-off Active. Minimum Engine RPM = 1600 RPM. Upstream O2S less than .471, the PCM begins the Downstream O2S rationality test. The PCM looks at the Downstream O2S volts for 5 seconds, if less than .295 volts, the test passes. If the Downstream O2S is greater than .295 volts, the test increments a count of 1 and the test is done again. A count of 3 will set a DTC and store Freeze Frame Data.

Rich (High Voltage) Output Test
Engine coolant temperature is above 170°F. At WOT TPS voltage for more than 2 seconds. The Upstream O2S volts above .490 volts, the PCM begins the Downstream O2S rationality test. The PCM looks at Downstream O2S volts for 5 seconds, if more than .608 volts, the test passes. If the Downstream O2S is less than .608 volts, the test increments a count of 1 and the test is done again. A count of 3 will set a DTC and store Freeze Frame Data.

EGR Monitor
EGR Solenoid is enabled, vehicle speed more than 3 MPH. Time from Start/Run is more than 2:09 minutes. The Fuel Control in Closed Loop. No Limp-In or OBD II Monitor faults present. Purge is enabled. Engine coolant temperature more than 144°F. MAP Range during Monitor: 11.70" to 16.20". RPM Range during Monitor: 2200 RPM to 2400 RPM. Actual TP Sensor above minimum TP Sensor Range: .295 volts to 1.0 volt. Maximum Short Term Adapt = +6%. The PCM stores the EGR on Short Term Adaptive Memory value. The PCM begins the monitor. The PCM turns off the EGR Solenoid. The PCM uses a modified ramp rate for Short Term Adaptive Memory. The PCM stores the EGR off Short Term Adaptive Memory value. The PCM determines the Short Term Adaptive Memory shift. Between 3% to 17% Short Term shift adaptive memory an EGR Monitor passes. Less than 3% rich or more than 17% shift rich will run the test again. 3 failed tests will equal a 1 trip EGR Monitor Failure.

Catalyst Monitor
Engine coolant temp above 170°F. Accumulated open throttle time of 3:00 minutes. The vehicle speed above 20 MPH and the TP Sensor is open for 4:00 minutes for an ATX or 5:00 minutes for a MTX.

NOTE: If the vehicle speed drops below 20 MPH or the throttle is closed the timer counts back down until the vehicle speed is above 20 MPH, then the counter resumes counting up again. MAP range during monitor: 14.60" to 18.20". The RPM range during monitor: 1500 RPM to 2000 RPM. The time spent in the above MAP and RPM ranges should be more than 3.9 seconds. No Limp-In or OBD II Monitor faults present. The PCM begins the monitor. The PCM starts a timer and counts the Upstream O2S switches and counts the Downstream O2S switches until 20 seconds is reached. After 20 seconds is reached, the PCM divides the Downstream O2S switches by the Upstream O2S switches to determine the switching frequency. If it is less than the calibrated amount, the catalyst monitor passes. If it is more than the calibrated amount, the test increments a count of 1 and the test is done again. A count of 2 will cause the monitor to fail 1 trip and store Freeze Frame Data.

Purge Flow Monitor
A Purge Free Cell Update must take place. ATX transmission is in gear at idle, Cell 12, or an MTX is in Cell 13. To do a Purge Free Cell Update, the engine must be running In Closed Loop, engine coolant temperature above 170°F for more than 1 minute. The PCM attempts a Purge Free Updated every other time the Cell is entered. The engine must remain in the Cell for 20 seconds to complete a Purge Free Update. The Purge Free Cell will update once the Purge Duty Cycle returns from 0% to some other value, and the PCM begins Stage I of the Purge Flow Monitor.

Stage I: If any of the Purge Normal Cells are richer than their Purge Free Cell Mirrors by the calibrated amount, Stage I Passes. Stop testing this trip. Stage I Pass Specifications:

If less than the spec, continue with Stage II.

Stage II: delay for 1 second from Stage I. Minimum Baro more than 21.70". Maximum Throttle Change (TPS) less than .060 volts. Maximum MAP vacuum change less than 0.50" vacuum. Maximum RPM change less than 96 RPM. Maximum charging system voltage change less than 0.99 volts. Maximum generator duty cycle change less than 14% duty cycle. The PCM updates the Cell with purge on for 1 seconds. The PCM updates the Cell with purge off for 2 seconds. In Stage II, the PCM subtracts the Purge Normal Cell value from the Purge Free Cell Value. If the difference is greater than calibrated amount, Stage II Passes and no further testing is performed that trip. If the difference is less than the calibrated amount, continue testing. The PCM averages the Short Term Adaptive Memory percent and the RPM for 3 seconds. The PCM stores the averaged Short: Term Adaptive Memory and the RPM value and then reads and stores the IAC Steps. The PCM begins increasing the Purge Flow (by increasing the Purge Solenoid Duty Cycle) .40% every 44 milliseconds. The PCM begins a new averaging for Short Term Adaptive Memory and RPM. The PCM continues taking new IAC step readings. The PCM compares Short Term Adaptive, RPM and IAC Steps from before the Purge Duty Cycle was increased during Stage II until 1 of 3 things happen:
Short Term Adaptive % changes by 5.0%.
IAC Steps change by 1 Step.
RPM changes by approximately: 100 RPM
If any of the above happen, Stage II passes. If not and 99% Purge Solenoid Duty Cycle is reached, Stage II Fails. This will cause the Purge Flow Monitor to Fail 1 Trip and Freeze Frame Data will be stored.

Secondary Air Monitor
Stage I runs when the Secondary Air Solenoid is on (Upstream Air Added). The Secondary Air Solenoid is switched on, or goes from blocked to upstream air under the following conditions:
Secondary Air Sol on Times:
Engine Running
Coolant Temp after Start-Up below 120°F ECT = 2:00 minimum; above 120°F ECT = 0:20 minimum
In Decel and all items met:
Engine Temp above 0°F
Engine Temp below 154°F
MAP above 19" vacuum
RPM above 1220 RPM
RPM below 3500 RPM

The PCM begins Stage I: The PCM monitors the Downstream O2S while the Secondary Air Solenoid is on (in the Upstream mode). If Downstream O2S is below .725 volts, the PCM goes to Step A. If Downstream O2S is above .745 volts, the PCM goes to Step B.

A. If the Downstream O2S is less than .725 volts, the PCM waits for the Secondary Air to be turned off. After the Secondary Air is turned off, the PCM monitors the Downstream O2S for 2 Seconds. If the Downstream O2S voltage is now above .745 volts, Stage I Passes and all testing is stopped this trip. If it is not above .745 volts, Stage I fails and Stage II begins.

Or

B. If the Downstream O2S is greater than .745 volts with the Secondary Air Solenoid on (Upstream Air Mode), then the PCM fails Stage I and Stage II begins.

The PCM begins Stage II after the following:
Stage I Failed.
Fuel System in Closed Loop.
At Idle.
Test not already failed this Trip.
RPM above 700 RPM

In Stage II PCM richens the mixture until the Downstream O2S switches rich by doing the following:
The PCM changes the Upstream O2S rich switch point from .490 volts to 1.02 volts
The PCM increments a counter by 0.02 volts every 2 seconds
The PCM stops updating Long Term Adaptive Memory
The PCM turns off the purge solenoid (No Purge Flow)
The PCM uses the Purge Free Idle Cell value for fuel calculations
The PCM modifies the Fuel Ramps of Short Term Adaptive Memory

If the Downstream O2S does not switch to rich (above .745 volts) before the Upstream O2S counter gets to 1.12 volts, The PCM fails Stage II and the Secondary Air Monitor fails 1 trip and Freeze Frame Data is stored.

Or

If, the Downstream O2S switches to rich (above .745 volts) before the Upstream O2S counter gets to 1.196 volts, The PCM turns the Secondary Air Solenoid on (Upstream Air Mode). The PCM resets Short Term Adaptive Memory to -1.5% and begins reducing the Short Term Adaptive Memory by -0.39% every 0.430 seconds until the Upstream O2S is below .859 volts.

Once the Upstream O2S is below .859 volts, the PCM holds the Short term Adaptive Memory at its present value.

The PCM checks to see if the Downstream O2S has switched below .725 volts, if so, the PCM Passes Stage II and no further Testing is done this Trip. If the Downstream O2S has not switched below .725 volts, wait a maximum of 20 Seconds. If either 20 Seconds passes or the Downstream O2S has not switched below .725 volts, the PCM fails Stage II Secondary Air Monitor fails 1 trip and Freeze Frame Data is stored.

Oxygen Sensor Heater Monitor (both Up and Down O2S)
Engine running at least 5 minutes.
Shut the Engine off.
Minimum battery voltage with engine off is more than 10 volts.
The PCM delays for 5 seconds.
The PCM keeps the power to the O2S Heaters off (keeps the ASD Relay off for now).
The PCM begins pulsing the O2 Sensors with 5 volts for 35 milliseconds every 1.6 Seconds.
The PCM then monitors the O2S voltage before and during each pulse.

If the initial voltage difference between the Pulse on and Pulse off minus the next Pulse on and Pulse off difference is more than 1.5 volts, the Oxygen Sensors are too cool and all testing is stopped. If the initial voltage difference minus the next voltage difference is less than 1.5 volts, the Oxygen Sensors are properly heated and the testing continues. Next, the cool-down phase begins. The PCM continues to pulse the Oxygen Sensor with 5 volts and then back to .45 volts. The PCM monitors and stores the first Pulse on and the first Pulse off voltages and then subtracts them from each other. The PCM then subtracts the voltage difference from each new set of Pulse on and Pulse off reads, to the difference of the voltage reads taken just before. Once the PCM sees a difference between readings of at least .490 volts, the sensors have properly cooled and the O2 Sensor Heaters are ready to be tested.If 3:40 minutes have elapsed and still a voltage difference of .490 has not been reached, begin heating the O2 Sensor that has cooled and disable testing on the O2 Sensor which has not fully cooled.If all Oxygen Sensors have cooled properly, the PCM then grounds the ASD Relay (to provide the O2S Heaters with voltage).The PCM continues to Pulse 5 volts to all O2 Sensors after the ASD Relay is turned on. The O2S Heaters can pass by one of two methods: First, with the 5-volt Pulse on, the PCM compares to the next 5-volt Pulse on value. If the voltages between spikes (on Pulses) has decreased by .157 volts. The O2S Heater monitor passes and all testing is stopped this trip second. The voltage difference between the Pulse on voltage is compared to next Pulse on voltage and is less than the prior voltage Pulse on, for 10 out of the 30 Pulses (33%), this indicates a Heating Trend and the O2S Heater Passes. If neither a Heating Trend nor the Absolute voltage is reached, the O2S Heater monitor fails 1 trip and the Freeze Frame Data is stored.

Mis-Fire Monitor
Mis-Fire monitor is continuously running during engine operation. For the Mis-Fire monitor to be enabled, the Adaptive Numerator must be learned since battery disconnect and every Key on there after (known as Power-on learning).

The Adaptive Numerator is a software learning routine that tells the PCM where the crankshaft slots are. Since every crankshaft is different, the PCM must learn exactly where its particular crankshaft slots are; otherwise its RPM calculations would be wrong.

After a battery disconnect and then a power-up of the PCM, the Adaptive Numerator is set to a value which it would be at if everything were perfect (crankshaft slots, sensors, PCM hardware, etc.). If the Adaptive Numerator is equal to the default value, no learning has happened and the Mis-Fire Monitor will not run.

To allow the PCM to learn the Adaptive Numerator, the following must happen:
Open Throttle
Engine Cool Temp above 100°F Or if below 100°F,
Wait for ECT rise of 59°F
More than 10" Vacuum
Above 1200 RPM
Below 3000 RPM - ATX
Below 3488 RPM - MTX

Once the PCM has learned the Adaptive Numerator, the Mis-Fire Monitor will run.

Fuel System Monitor
Fuel System monitor is continuously running during engine operation