# 01 Altima Idle surge



## baddragster225 (Jan 25, 2018)

I have a 01 Altima 2.4 with a 5speed. Found the intake was leaking and fixed that problem but another has came about. When driving the car upon slowing to a stop I noticed the car will rev between 1,000 to 2,000 rpms until you come to a complete stop and if you coast the car out of gear and foot of the gas pedal the rpms will began to raise and do the same thing. clutch in or out it makes no difference. I have replaced the IAC valve, TPS, mass air flow sensor. Not sure what it could be. Any input would be a great help. Thanks a lot!!!!


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## RJ64 (Jul 23, 2017)

You said that you fixed the intake leak, but where was it leaking and what did you do? If you replaced the intake gasket, the one between the intake manifold and cylinder head, are you SURE that it isn't leaking anymore? What you have described is the same thing that many cars I have owned have done because of an intake leak. Make sure all your vacuum hoses aren't damaged while you are at it. They are 17+ years old now, and rubber eventually hardens and cracks and it is very easy to miss that. Take your time when checking these things and have someone check after you do. You can spray WD40, or a similar product, at a suspected leak area to see if the idle changes as a way to find a vacuum leak. Flammable spray products can cause FIRE, so I wouldn't do that. Try the simple stuff first before you spend too many $$.


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## rogoman (Dec 16, 2004)

Spray testing for vacuum leaks is not very accurate. Use a vacuum gauge for good accuracy; most auto parts stores sell vacuum gauges. To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source, usually somewhere on the intake manifold. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. At about 3,000 RPM, it should be around 21 InHg.

If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. The gasket may have failed; spray a water mist at the gasket to see if the gauge reading changes. Also check the intake plenum bellows at the throttle body and at the MAF for cracks or loose clamps.

I had a '91 240SX with the same problem as yours. My fix was a bad seal at the output side of the MAF where there is a clamp. I found it by watching the vacuum gauge during idle and pushing against the plenum hose; found the problem spot by a major deflection in the vacuum gauge.


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## matthias (Jun 11, 2018)

Nice information . ..


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