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Car Forum / Nissan / Nissan Cars / May 20051999 Nissan Maxima knocks when idle
I have a 1999 Nissan Maxima GLE driven for about 60,000 miles. I noticed that since the past few weeks, the car knocks when it is idle (when engine is warmed up). It happens when I stop at a light or when I am stuck up in traffic. I do not notice the knock during regular driving. I use 91 octane level gas in it. Any ideas what might be causing this... I had the car serviced for 60K miles at the dealers site a month ago. The computer showed no error codes. Thanks your knock sensor is most likely worn out... dealer will want 400 bucks to remove the intake manifold to replace the sensor (3 hours labor) the sensor is located in the top of the engine in the middle under the intake manifold you can go to sears and get a 12 mm jointed socket (around the corner) that fit on the end of a couple of feet of the 1/4 socket extension. this will allow you to remove the sensor without removing the intake manifold do a Google search for maxima knock sensor for more detailed instructions john -- Yes this is my truck. No I won't help you move >I have a 1999 Nissan Maxima GLE driven for about 60,000 miles. I > noticed that since the past few weeks, the car knocks when it is idle [quoted text clipped - 8 lines] > > Thanks > your knock sensor is most likely worn out... > dealer will want 400 bucks to remove the intake manifold At idle? I highly doubt it's the knock sensor. Could be a lot of things. I'd have a mechanic you trust listen to it. It's hard to diagnose noises over the internet. Have a qualified tech listen to this knock ordinarily the knock sensor would set a code and it would almost never cause an ign./timing knock at idle. >I have a 1999 Nissan Maxima GLE driven for about 60,000 miles. I > noticed that since the past few weeks, the car knocks when it is idle [quoted text clipped - 8 lines] > > Thanks >Have a qualified tech listen to this knock ordinarily the knock sensor would >set a code and it would almost never cause an ign./timing knock at idle. [quoted text clipped - 8 lines] >> I had the car serviced for 60K miles at the dealers site a month ago. >> The computer showed no error codes. Knock sensor does not detect mechanical knock. It only detects the frequency of ignition knock or pinging. This will usually happen at high load and moderate rpm, if it happens at idle then it would be pinging at all loads and speeds. A mechanical knock that only happens when warm is usually bad news. Check oil level and dig out the receipts for oil changes. Sounds like it's going to be a big end. Rev engine in neutral to about 2.5K and then take foot off throttle, if it knocks as it slows down on the overrun then it's almost 100% certain to be big end(s). Main bearings rumble as they all help each other. Tappets will rattle when cold before they rattle warm. Cams like mains all the journals help support the shaft so they won't knock as such. But it could just be something lose like a heat shield or engine mount. Could be a lot of things, from a hydraulic lifter that isn't pumping up, to piston slap or a loose wristpin. It could even be one of the pumps driven off the serpentine belt making noise. It is almost impossible to diagnose a rattling or knocking engine noise like that without actually hearing it. I would have the dealer diagnose it. > I have a 1999 Nissan Maxima GLE driven for about 60,000 miles. I > noticed that since the past few weeks, the car knocks when it is idle [quoted text clipped - 8 lines] > > Thanks If it was rod bearings you hear a rattle on revving the engine. Doubt it's mains either. Could be piston slap -- lifters. You should have a qualified mechanic listen to it. |
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