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cloe0626, Auto Mechanic
Category: Cadillac
Satisfied Customers: 791
Experience:  was a mechanic in the army for four years and have been working at a dealer ship the past five years
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How to diagnose bad purge valve symptoms?

Customer Question

How to diagnose a bad vapor canister on a 2003 Cadillac CTS? What are purge valve symptoms?

Submitted: 1 year ago.
Category: Cadillac
Customer: replied 1 year ago.

My 2003 cts 3.2 engine wont start after fueling unless i go full throttle. Ive read that almost everyone fix their problem by changing the vapor canister purge valve, but i removed mine and checked it by applying 12volts and ground. It seems like its working fine, it clicks and i also blew thru the valve with no power on it and its sealed. Also sucked on it and no air passed thru until applying 12volts. Replaced vent solenoid, the one that goes inside the canister cause its only 30 bucks. Still acting the same when fueling. I have codes for o2 sensor bank 2 sensor 2 that i have not replace and just got crankshaft position sensor code recently. No issues after being able to start the car. I have a scanner and manually opened the purge valve to 100 and the car stumbled and quit running. Did the same thing with the vent valve triggered it on and the car quit. I reset the values and car ran fine as usually. Problem only happens after adding fuel.

Expert:  cloe0626 replied 1 year ago.

This situation continues, these vapors can flood the engine cylinders, resulting in an abnormal fuel mixture getting created and burned. This causes the engine to misfire and choke.

2) Failure to Clear Emission Tests

Every car on the road is required to pass the sate-sanctioned emission test, which imposes an upper-limit on the various gases and pollutants that come out through a car's exhaust. If the canister purge valve malfunctions, it may be unable to redirect the fuel vapors back into the emission system. These vapors contain harmful hydrocarbons, which will then escape through the car's exhaust, and therefore show up in the emission tests. Thus, if your car fails the emission test, its purge valve may be at fault.

3) Damaged Gaskets

A normally functioning purge valve releases fuel vapors into the charcoal canister, where they are stored until they are recycled. A bad purge may not open to allow these vapors to pass. As a result, pressure will start to build inside the system. This pressure can be so intense that it can blow out the gasket and rubber seals, causing oil to leak and get sprayed out of the emission system and onto the engine and engine compartment. If left unresolved, this will create even more severe issues.

4) Damaged Spark Plugs

A faulty purge valve may by unable to redirect the fuel vapors into the engine's cylinders for combustion. As a result, an unnecessarily rich fuel and air mixture will get combusted during each cycle of the engine. This produces extra heat, which in the long run will wear out the spark plugs. Thus, if your car's spark plugs seem to have worn out earlier than expected, most likely, the purge valve in your car is not functioning properly.

Customer: replied 1 year ago.

What should I test to find my problem? I replaced the evap vent solenoid. Checked purged solenoid by applying 12 volts it opens and close. Triggered both solenoids with scanner. Engine shuts off when triggered. What should i do?

Expert:  cloe0626 replied 1 year ago.

If it shuts of when you trigger the solenoids then I would replace the purge valve because it shouldn't shut off

Customer: replied 1 year ago.

ok. My scanner gives me the option of the purge valve and what percent I want it. I gave the purge v.alve 100%. Thats when the engine stumbled and then shut off. So it should not do that? If this is my problem, Ive looked for that purge valve every where literaly. Where can i order it from? My car has the 3.2 engine.

Expert:  cloe0626 replied 1 year ago.

Here is the part it for 2005 but its compatible with your motor.

Customer: replied 1 year ago.

Even tho its for the 3.6 its compatible with my engine? Supposedly the one that's for my car comes with the lines attached to the solenoid. Just want to verify before ordering.

Expert:  cloe0626 replied 1 year ago.

I ran a compatibly check it will work.

If you need anything else please let me know and rate my service when you get the chance.

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