Trionic OBDII Enhanced EVAP Test Procedure

1. Preconditioning:

M. Fuel level must be between 1/4 and 3/4 full for test results to be accurate.

N. Extremely hot or extremely cold ambient temperatures may affect test results. When a very cold vehicle or a very warm vehicle is brought into a shop at "normal room temperature, high fuel vapor pressure is present in the fuel tank. For this reason, we recommend a "drive cycle" to bring the fuel temperature closer to the ambient temperature.

O. Drive cycle - drive the vehicle under varying speed and load conditions for 5 to 10 minutes.

P. Bring the vehicle into the shop, connect Tech 2 or ISAT and monitor Tank Pressure with the engine running.

For the most accurate readings, use Tech 2, "Read Values". Highlight "Tank Pressure" and press ENTER to display a graph with current tank pressure readings in the lower left-hand comer of the display.

Q. Shut off the engine, energize the canister close valve with jumper wires and monitor "Tank Pressure". You should hear the CCV click when you connect the jumpers. Tank pressure must not rise by more than 0.2 kPa within one minute. If the tank pressure rises more than 0.2 kPa within one minute, this indicates a vapor pressure which may affect test results. You must either repeat the drive cycle or allow the vehicle to stabilize at room temperature for several hours, then repeat this check.





(Note:
On M96.5 models, the 2-pin connector for the canister close valve is located under the hood as shown in Figure 2. On 1997 models, this connector is located inside the right fender. On 1997 models, remove the turn signal for access to the CCV.





2. Leave the canister close valve energized with jumper wires.

^ Tech 2 Read Values - Tank Pressure

^ Disconnect EVAP valve

^ Start engine





3. Reconnect the EVAP valve. Leave the canister close valve energized with jumper wires.

NOTE:
In this step you will allow intake manifold vacuum to pass through the EVAP valve and cause a slight vacuum (pressure drop) in the tank. In most cases, this pressure drop will take place quickly. For the most accurate test results, it is important to SHUT OFF THE ENGINE as soon as the tank pressure is -1.0 kPa. Never allow the tank pressure to drop below -2.0 kPa.

Tech 2 - Read Values - Tank Pressure

Start engine, run until EVAP cycles (> 140°F [>60°C]). You can feel the EVAP valve "clicking".





4. Leave the canister close valve energized with jumper wires.

With the tank pressure still at -1.0 kPa from the previous step, monitor mading for one minute after you have shut off the engine. Check the tank pressure after one minute.

NOTE:
In steps # 5 through # 9, you will be using a hand vacuum pump and the Saab Turbo Boost Gauge to search for a small vacuum leak. It is important that the hand pump and gauge do not leak!





5. Disconnect vent hose from filler neck and connect the Saab Turbo boost gauge, P/N 83 94 514 to the end of the hose.

^ Disconnect vent hose from throttle housing (which goes to the EVAP valve) and connect a vacuum pump to the end of the hose.

^ Energize the canister close valve with jumper wires.

^ Energize the EVAP with a jumper wire.





6. Remove the inner fender.

^ Disconnect hose from canister which connects to the tiller neck.

^ Connect vacuum pump to this hose.





7. Remove the canister and the canister close valve (as a unit) to bench test.

^ Connect vacuum pump to one of the small ports on the canister.

^ Connect the turbo boost gauge to the other small port.

^ Energize the canister close valve with jumper wires





8. Remove the canister close valve from the canister and put it aside for now.

^ Plug 2 of the ports in the canister. Connect a hose to the 3rd port.

^ Submerge the canister in a container of water.

^ Use a hand pump (NOT shop air pressure) to blow into the 3rd port.








9. Check the canister close valve by connecting the turbo boost gauge and vacuum pump to the hose on the end of the canister close valve with a "tee". Energize the canister close valve with jumper wires.

10. Final check:

Clear the diagnostic trouble code.

Perform a driving cycle:

^ Ignition switch in the ON position, A/C switched off. Connect a jumper wire across the fan relay so that the low speed radiator fan runs continuously.

^ Start the engine and run it at idling speed until the temperature of the coolant exceeds 140°F (60°C) or for at least 1 minute if this temperature is reached earlier.

^ Depress the accelerator for a second or two and then run the engine at idling speed for 30 seconds. Repeat three times.

Evaluation of the driving cycle:

^ Connect Tech 2 or ISAT.

^ Select "DIAGNOSTIC STATUS".

^ Select "EVAP".

When "Diagnostic Status/EVAP" displays "READY", recheck to see if the DTC has recurred.

[YES]

P0442:

^ Carefully perform all of the leak checks again (step # 5 to # 9) to make sure that there is not a small leak that you have overlooked.

^ Call the Technical Assistance Center. Be sure that you have notes regarding ALL of your test results, including the ECM program version.

P0455:

^ Carefully check the canister close valve for an intermittent mechanical operation. It might intermittently not seat correctly internally, causing a failure of the first portion of the test. Also check the canister close valve electrical circuit.

^ Check with the customer to make sure that they are not refueling the vehicle with the engine running. If the diagnostic procedure runs during refueling, the ECM will determine that there is a Large Leak (P0455). This is VERY RARE, but it is a possibility.

[NO]

If you have not found a leak, and the vehicle has a history of recurring M.I.L. accompanied by DTC P0442 or P0455, then contact the Technical Assistance Center at 1-800-766-2857.