Honda civic 2002 P1457, Evap canister purge valve
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Honda civic 2002 P1457, Evap canister purge valve
According to Honda civic 2002 service manual, the vapor canister purge valve is supposed to hold vaccum when de-energized and open when energized.
Looking at the picture bellow from their service manual, they seem to apply vaccum on the valve side connected to the Canister side . Both my new and old valves are only holding 5in.HG vaccum applying vaccum from the canister side.
In my mind, we should test that valve with the vaccum applied to the valve side connected to the intake manifold cause manifold is applying vaccum to the valve, not the Canister. Also, having an arrow symbol on the valve make me think it is designed to hold vaccum only from one side : manifold.
Only the picture put a doubt in my mind...
Looking at the picture bellow from their service manual, they seem to apply vaccum on the valve side connected to the Canister side . Both my new and old valves are only holding 5in.HG vaccum applying vaccum from the canister side.
In my mind, we should test that valve with the vaccum applied to the valve side connected to the intake manifold cause manifold is applying vaccum to the valve, not the Canister. Also, having an arrow symbol on the valve make me think it is designed to hold vaccum only from one side : manifold.
Only the picture put a doubt in my mind...
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Re: Honda civic 2002 P1457, Evap canister purge valve
As pictured it doesn't make sense, especially since they don't tell you a spec or a limit to how much vacuum to test with.
Dynamically, the intake manifold vacuum is significantly higher than what one will ever find in the EVAP system, so the purge valve needs to be able to seal 100% against the manifold vacuum. I'd test it that direction (manifold side) with 25", not as pictured.
As pictured I'd expect sealing against only a couple inches of vacuum would be necessary.
As pictured I'd expect to run the engine and make certain the vac gauge does NOT move until the valve is opened.
When EVAP testing is done by the PCM, the tank/canister is only put under a slight vacuum. Maaaybe 2" or so MAX, because a strong vacuum will collapse the plastic fuel tank. (The fuel cap should also vent around that point to prevent tank collapse)
HTH
Dynamically, the intake manifold vacuum is significantly higher than what one will ever find in the EVAP system, so the purge valve needs to be able to seal 100% against the manifold vacuum. I'd test it that direction (manifold side) with 25", not as pictured.
As pictured I'd expect sealing against only a couple inches of vacuum would be necessary.
As pictured I'd expect to run the engine and make certain the vac gauge does NOT move until the valve is opened.
When EVAP testing is done by the PCM, the tank/canister is only put under a slight vacuum. Maaaybe 2" or so MAX, because a strong vacuum will collapse the plastic fuel tank. (The fuel cap should also vent around that point to prevent tank collapse)
HTH
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