When I first bought this car last year I had a 455 code with the check engine light. New gas cap fixed the problem.


Now it's back again. I found and fixed two small vacuum leaks under the hood. One was in the small line going from the throttle body to the fuel pressure regulator they other was in the 180 degree bend that goes to the purge canister.


The code went away for a week after I fixed those and cleared the code but now it's back.


Is there a way to test the purge canister to see if it's bad? I pulled the line off if it that goes back to the fuel tank and put on a vacuum gauge and it pulls a steady 18-20 inches of vacuum all the time. Starts slow but then finally climbs and stays at 18-20. I'm not sure if I understand how the purge canister works but should it pull that much vacuum all the time? I searched all over net but I can't find out how to test that part. Any ideas?

 

is this what you were looking for

STATIC CHECK:

The canister purge valve is checked by carrying out the following steps:

Resistance measurement. Turn ignition off. Remove the connector of the canister purge valve and measure the resistance across the two terminals of the coil. The resistance (depending on the type of valve) can vary from ± 15 ohm to ± 75 ohm.
Checking the wiring. Turn ignition off. Remove the connector of the canister purge valve and the plug of the ECU. Measure the resistance between the terminal in the connector of the canister purge valve and the corresponding terminal in the plug of the ECU. The resistance should be less than 1 ohm. If not, check the wiring and connectors and repair them, if necessary.
Voltage check. Turn ignition off. Remove the connector of the canister purge valve. Start the engine and measure the voltage on the positive terminal of the connector. Check if the supply voltage is present. If the supply voltage is not present, check the relay, and if it is present, check the fuse. Also check the wire connection between the relay and the canister purge valve.
DYNAMIC CHECK:

An oscilloscope is used to check the signal of a canister purge valve.

Figure 1 shows the voltage image during triggering of the canister purge valve by the ECU. Connect one measuring pin of the oscilloscope to the signal wire of the canister purge valve, and the other to the ground of the battery. Start the car and check if the canister purge valve is triggered with pulses. Duty cycle triggering frequency differs per ECU. Triggering of the valve can also depend on engine temperature, engine speed and engine load, among other things.
There are also systems whereby the valve is powered continually.

Visual inspection. Check the connectors and wiring for damage. Check the hose connection between the canister purge valve and the intake manifold, and between the canister purge valve and the carbon filter for damage. Check the canister purge valve for mechanical breakage. Repair these if necessary.
Mechanical check. Remove the connector from the canister purge valve and check if the connection between the two connectors from the valve is closed. Connect 12 V on the canister purge valve and check if the connection is open.

 

Thanks. This is the type of thing I needed.




I have a strong feeling that it is the purge valve. After the check engine light had been on for a week the tests I did the other day must have done something. After I put it back together and drove it 5 miles the light went off. It's been 2 days now and I've started it a half dozen times and put 20 miles on it and no light. If it comes back on and shows the same code I'll put your troubleshooting tips to use.