Enhanced Evaporative Emission Troubleshooting
Perform the following to inspect the system for leaks:Note 1:
The procedure described below assumes that all electrical connections are in good condition.
Note 2:
A "test" hose should be made from an 18 inch (457.2 mm) length of 3/8 inch (9.53 mm) fuel hose to perform most of the diagnostic procedures.
Note 3:
Two pairs of hose pinching pliers (Snap-On part # BLG2 or equivalent) will be needed to help troubleshoot the system.
1. Referring to the appropriate schematic, connect and clamp the "test hose" to the following hose in the system:
1998 Sonata:
The hose is located between the canister and the two way valve (Photo 1 - Left, rear of vehicle).
1998 Elantra/Tiburon:
The hose is located between the canister and the canister close valve (Photo 2 - Left, rear of vehicle).
Note:
For 1998 Elantra/Tiburon, the fuel tank must not be completely full to perform the following procedure. If the fuel tank is completely full, the waveform may not be as easy to evaluate.
1996/97 Elantra/Tiburon
1997 DOHC/1998 Accent
The hose is located between the canister air filter and the canister close valve (Photo 3 - Left, front, inner fender of vehicle).
2. a. Connect HDS to the vehicle, enter"SIMU-TECH", then select "SIGNAL WAVEFORMS".
b. At the signal selection screen, select "ORDER", "BY NAME" and then "DIFFERENTIAL PRESSURE SENSOR".
c. Select "OPTIONS" and select "DIGITAL RECORD".
d. Select "OK" and then select "RUN".
e. Set the ignition switch to the "ON" position.
f. While watching the DPS signal on HDS, GENTLY begin to blow into the fuel hose with approximately 1.0 psi (the DPS voltage should begin to rise). Continue to gently blow into the hose until the DPS voltage is approximately 4.0 volts.
Do not over pressurize since the sensor cannot read over 4.7 volts.
3. a. When the DPS reads approximately 4.0 volts, immediately clamp the "test" hose with hose pinching pliers (see Photo 4).
b. In a good system, the voltage will remain steady or even rise slightly if the canister is at the rear of the car (the value must remain constant: +/- 0.05 volts over 10 seconds). If the voltage drops, go to step E. If the voltage remains steady, go to step C.
c. By removing the hose pinching pliers, the system should return to atmospheric pressure (2.5 +/- 0.2 volts) within 25 seconds. If the voltage takes longer than 25 seconds to return to 2.5 +/- 0.2 volts, go to step D. If the voltage returns in less than 25 seconds, go to step J.
d. If it takes longer than 25 seconds, check for restricted vapor hoses or internal blockages in the "to tank" circuit. Correct any conditions found. Repeat step 2.
e. If the DPS voltage decreases after clamping, a leak is present in one of the circuits or at the canister. Isolate the leak into either the Purge, Tank or Fresh Air circuits. Use the procedure outlined below.
f. Pressurize and clamp as described in steps 2 and 3a, and connect a second set of hose pinching pliers at the "to tank" vapor hose on the canister. If the voltage drops, go to step G. If the voltage remains steady, go to step 1.
g. Pressurize and clamp as described in steps 2 and 3a, and connect a second set of hose pinching pliers at the "purge" vapor hose on the canister. If the voltage drops, go to step H. If the voltage remains steady, go to step 1.
h. Inspect the canister for a small leak by clamping both the "purge" and "to tank" vapor hoses, and supplying a low pressure source (approximately 1 psi) into the fresh air nipple, while spraying the canister with soapy water. If a leak is found, replace the canister. If no leak is found, repeat procedure starting at steps 2 and 3a.
i If the DPS voltage remains steady after the second set of hose pinching pliers are clamped, then the leak is on the other side of the "clamped" circuit. Pressurize and clamp as described in steps 2 and 3a, each time moving the second set of hose pinching pliers farther away from the canister, but in the same circuit until the leak is found. The "test hose" connection may have to be moved to different areas when checking the "to tank" circuit. Use the schematic to try to keep the DPS in the system when pressurizing and observing for leaks.
j. If no apparent leak is found, thoroughly check the "fresh air" circuit and the canister close valve as described in "canister close valve inspection".