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I have tried to look this up, but I'm confused. The vacuum lines are good, but when i disconnect the vac line from the EGR (engine off), I can blow/suck air through it. Should This be happening? Also, with engine running and warm, I can feel no vacuum when i disconnect the vac line from the EGR and put my finger over it. Is this normal? I am getting a 33 code, and have already replaced the EVP, but continue to get this code over a year later.

HELP!!!

89 351w
 

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Satyr of the Midwest
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17,736 Posts
I have tried to look this up, but I'm confused. The vacuum lines are good, but when i disconnect the vac line from the EGR (engine off), I can blow/suck air through it. Should This be happening?
You shouldn't be sucking on anything under the hood, but I'm not one to judge. :rofl:

The EVR 'output' to the EGR valve is essentially open to the atmosphere when the engine is off or idling, so that behavior is completely normal.

Also, with engine running and warm, I can feel no vacuum when i disconnect the vac line from the EGR and put my finger over it. Is this normal?
Would you want EGR at idle? No. Therefore, there should be no appreciable vacuum at the EGR valve at idle. The only time vacuum is applied to the EGR valve is during regular operating conditions, i.e. cruising and light acceleration.

I am getting a 33 code, and have already replaced the EVP, but continue to get this code over a year later.
If you used a cheap-o AutoZone part, that's probably why, but there could be other reasons. Don't replace it again without TESTING it first! The EVP voltage should be around half a volt (between the EVP and SIG-RTN lines) with the key on and engine off; the voltage should be more than ~0.2V, but less than ~0.6V. If there's no voltage signal, make sure you're getting VREF and SIG-RTN at the EVP connector; there should be almost exactly 5.00V between those two terminals.
 
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