Check those PCV valves
Joined: Aug 2003
Posts: 6,573
Likes: 72
From: Kansas City
Check those PCV valves
For the past 6 weeks or so, the part throttle acceleration of my car felt a bit flat and not quite right. While I was at my last auto-x event, I had the hood up while the car was idling between runs and I heard a hissing sound coming from the area of the PCV valve (forward passenger side valve cover). It was a sound I had never heard before. While a PCV valve does have some noise associated with it, this was much louder than normal. When I got home, I pulled the valve. Everything seemed fine, but when I applied to vacuum to the valve, it would not hold it. There was a small leak or obstruction letting a small bit of air through. The correct operation of the valve is to close under high vaccum situations such as throttle throttle acceleration. At WOT, there is no vacuum therefore the operation of the valve isn't that important. I attempted to clean the valve, but it would still leak. I called around to all the Nissan and Infiniti dealers and none of them stocked the valve because they said it never failed. I would agree, I've never had a PCV valve fail before, but I guess there's always a first time. I ordered a new valve, got it, and tested it. It held vacuum perfectly. I put the valve in and driveability was back to normal. My MPGs are up about 10% too over the past 2 weeks even with the cooler temps.
For the past 6 weeks or so, the part throttle acceleration of my car felt a bit flat and not quite right. While I was at my last auto-x event, I had the hood up while the car was idling between runs and I heard a hissing sound coming from the area of the PCV valve (forward passenger side valve cover). It was a sound I had never heard before. While a PCV valve does have some noise associated with it, this was much louder than normal. When I got home, I pulled the valve. Everything seemed fine, but when I applied to vacuum to the valve, it would not hold it. There was a small leak or obstruction letting a small bit of air through. The correct operation of the valve is to close under high vaccum situations such as throttle throttle acceleration. At WOT, there is no vacuum therefore the operation of the valve isn't that important. I attempted to clean the valve, but it would still leak. I called around to all the Nissan and Infiniti dealers and none of them stocked the valve because they said it never failed. I would agree, I've never had a PCV valve fail before, but I guess there's always a first time. I ordered a new valve, got it, and tested it. It held vacuum perfectly. I put the valve in and driveability was back to normal. My MPGs are up about 10% too over the past 2 weeks even with the cooler temps.
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according to the FSM, you can check this by removing the PCV valve from the rocker cover (valve cover) while idling. You should hear a hissing sound if its working properly. Also, you should feel a strong vaccuum immediately when you press your finger to cover the valve.
Joined: Aug 2003
Posts: 6,573
Likes: 72
From: Kansas City
according to the FSM, you can check this by removing the PCV valve from the rocker cover (valve cover) while idling. You should hear a hissing sound if its working properly. Also, you should feel a strong vaccuum immediately when you press your finger to cover the valve.
Just saying that you should check this BEFORE you decide its not working properly. Its supposed to hiss somewhat...if its working. It shouldn't be too loud though.
That's interesting, back in the day, we changed the PCV valve with every tune up. And back then, we did that every 20,000 miles. I'll check mine as soon as I get a chance.
