# Gas mileage low, idling noise and other woes...



## faraway64dn (Apr 21, 2012)

First off, hello to you all. I don't know much about cars, but I've got a service manual, tools and a willingness to learn how to work on my own stuff.

My Altima is having some troubles:

Poor engine performance
- Low gas mileage: ~20 HWY MPG
- Slow to accelerate
- Ever higher RPMS needed to achieve the same level of performance
- "Psst" sound (like compressed air leaking) when accelerator is pressed.

Idling quirks
- When idling at stop lights, my engine RPM will spontaneously change (by about 200 RPM) and engine begins to rumble

P0136 Code (O2 Bank 1 Sensor 2)
- MIL light is on, blinks wildly when accelerator is pressed (sometimes)
- This is the rear 02 sensor, right?

Climate Problems
- Air comes through the vents regardless of whether I have the fan on or off. Heat and cold air work appropriately however.

Anyone have any advice for this? A little research indicates I should check the parts listed below. I'd appreciate it if someone could tell me the best way to do this and what to look for in these:

EGR Valve
Throttle body
Vaccuum leaks
Ignition coil
Fuel filter (getting replaced)
Fuel injector
Spark plugs (wells filled with oil, gaskets and plugs will be replaced) 

Thanks!
<= :newbie:


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## smj999smj (Jan 1, 2006)

The "MIL" flashes when it sees conditions that are detrimental to the catalytic converter; often this is a misfire and an ignition issue is the typical culprit (misfiring due to a shorted spark plug wire, etc.). A rear O2 sensor (yes, you have one) is a monitoring sensor and has no affect on driveability, so it would not be the cause of the flashing "MIL." I would suspect another code to be stored. All of the above are good things to check in your post. Spark plug well or wells filled with oil due to failed tube seals can cause a short between the cylinder head and spark plug boot, so that's a good and easy thing to check. If you have a rough idle, spray carb cleaner around the intake manifold gasket area, as these have been known to fail, as well. Check the rubber duct between the air cleaner and engine for splits, as well.


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