# Rough Idle - Odd Noise from Engine Bay



## PhxJosh (Jun 27, 2009)

I have been having problems with my 99 Nissan Sentra GXE. 

First, when I am sitting at a light, I can feel a pretty strong vibration that comes in spurts, enough to shake the steering wheel a good amount. 

The idle is not consistant, I can see the RPM needle slightly bump up and down, and I can slightly feel the revs. 

When I start my car, it spikes up to 1600-1800 RPMs but then drops down to around 800 after a minute of sitting, and it smells like gas when I am sitting. 

Also, I can hear what sounds like a slight rattle coming from the engine bay. Every now and then I hear a clicking, not sure what its called but I circled the thing that is clicking below:










Lastly, the shift from 1st to 2nd is rough, especially when the A/C is on. 

So I am thinking one or more of my mounts is bad, or what? 

Thanks!!!!!


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## PhxJosh (Jun 27, 2009)

I forgot to mention, I am also gettin a P0440 code (Evap Malfunction) which goes on and off randomly. Light will come on for a day or two, then go off, then come back on a few days later.


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## zacward (Aug 23, 2009)

Check the EVAP canister and the pcv valve. Gas fumes could be coming from the evap canister or just be a leaking injector seal.


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## pulsar86 (Aug 13, 2009)

Check all vacuum hoses for leaks also pollution hoses, a cracked or loose hose to carbon cannister will give you the fuel smell, and also the code, a vaccum leak will give you the rough idle. Also check that your intake manifold is tight. If you can get hold of a vacuum gauge a good reading is 22-24 inHg at idle.


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## PhxJosh (Jun 27, 2009)

zacward said:


> Check the EVAP canister and the pcv valve. Gas fumes could be coming from the evap canister or just be a leaking injector seal.


Where is the EVAP Canister and the PCV Valve located? 



pulsar86 said:


> Check all vacuum hoses for leaks also pollution hoses, a cracked or loose hose to carbon cannister will give you the fuel smell, and also the code, a vaccum leak will give you the rough idle. Also check that your intake manifold is tight. If you can get hold of a vacuum gauge a good reading is 22-24 inHg at idle.


Where do I get a vacuum guage? Would autozone have one to lend?


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## zacward (Aug 23, 2009)

On a 98 it should be on the drivers side of the car behind the fuel tank. It is just a plastic black cylinder-shaped canister. Should have some hoses on it.


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## pulsar86 (Aug 13, 2009)

Sorry I don't know if you could get a loan or hire one. Just look for any bad, loose or cracked hoses, you can usually spot them easily enough. You can usually find the pcv valve on any car by finding the hose coming off of the valve cover on the car and following it to the inlet manifold where you will find the pcv valve. If the valve is ok you will feel suction at the valve cover end when the car is at a fast idle speed. I would say that the hose leading off the rear left of the valve cover in your picture near the oil filler [ right side of car ] leads to your pcv valve. The valve looks like it might even be at the valve cover end [by the hex fitting in the picture] although this is not as common as at the intake end.


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