2004 Mazda MPV vacuum line from pcv valve and intake is closed flat. New mass air flow and hoses and pcv valve.
You have the wrong type hose on the pcv valvle. It isn't vacuum hose.
Testimonial: "thank you you have been very helpful i understand now but the hose that is on the new pcv valve is a vacuum hose "
The hose is too soft. Vacuum hose isthick walled to prevent collapse.
And checkto make sure the pcv valve is functioning.
In that case tat is a good question. Why is it collapsing. The pcv valve is new, the hose is new and the engine vacuum is normally 17 to 21 inches hg. The only other thing I can think of and it has happened to me on severaloccasions is that often when the hose is spooleld on the reel it is drawn too tight and the hose tends to be flattened. Of course this presets the hose to yield to thar flattened shap and although it is manually re shaped to round it has a memory and will now return to the flatter configuration with the added help of vacuun. The only time there is vacuum inthat hose is at cruising and deceleration and it is important to have the correct pcv valve so there is no restriction of flow. If it were not for backfire ignition of crankcase fumes there would be no need for the check valve feature in the valve. I hope you find remedy. Ned
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so what is causing it to close shut
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