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Blocked Hose From Vacuum Source To Pcv

1.4K views 1 reply 2 participants last post by  Nidan  
#1 ·
My '96 Sable wagon (Duratec) CEL came on and I read the two codes P0171 & P0174 ("System too lean (Bank 1)" " System too lean (Bank2)"). After perusing this site for the two codes for any hints, I too, found that the hose from the PCV valve to the metal pipe (vacuum source) had a split in it which was allowing outside air in. Had to use my mirror-on-a-stick to see it clearly, just as the instructions told me to do.

Basically, the hose had collapsed on itself due to age, oil contamination, pull of the vacuum, and the sharp 90 degree turn. I taped up the hose as a temporary fix only to find that the hose was blocked - it was blocked with the collapsed hose at the split.

So, with the split outside air was getting in but also the PCV valve cirucit was not being activated by the vacuum due to the blocked hose. Not exactly a winning combination.

My question is that just what is happening to the engine if the PCV cirucit is not operating ? I really couldn't tell between having the blocked pipe and when I put in a new one.

Bruce

PS - I was able to buy just that hose from a Ford dealer ($13). It was longer than the original hose so that the bend was much less than the 90 degrees in 3 inches.
 
#2 ·
The PCV system removes blowby gases from the engine block... all engines have a certain amount of blowby (gases leaking past the pistons while the engine runs). If these vapours build up, they contaminate and break down the engine oil, and can, in worst cases, cause seals to blow out and create oil leaks. Also, as you've learned, the split hose will cause a vacuum leak. Since you have the new hose on, you should be good to go. Just disconnect the battery for a few minutes to reset the PCM... that will also clear the codes and turn off the CEL. Then the PCM's adaptive fuel strategy will relearn without the big air leak.