# 2003 Altima with rough idle and loss of power



## ProfR (Mar 27, 2016)

I have a 2003 Altima 2.5S that is having problems idling. When I start it when the engine is cold, the RPM's are usually around the 1400-1500 range. Then after I drive it for about 10 minutes and let the engine idle, it will run fine for about 15 seconds before the RPM drops to the point where it stalls. I can hit the gas and bring it up to about 1000 RPM for 5-7 seconds and let off and it will idle fine for another 15ish seconds before doing it again. Also, while driving, the car feels like it randomly loses power. For example, taking off from a stoplight, the car will seem to lose power and no matter how much I hit the gas, the car will not accelerate like it should for about 7 seconds (It does accelerate though, just poorly for the amount I'm hitting the gas). This has caused issues on the highways when I am trying to pass someone but can't accelerate. There is no consistency in this; it happens randomly. 

It does have a check engine light on and the codes are P0507 (idle air rpm higher than expected) and P0138 (O2 sensor high voltage). I had the speed and revolution sensors replaced by Nissan a few months ago if that matters at all. Any help is appreciated.


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## rogoman (Dec 16, 2004)

The P0507 condition can be caused by the following:
● Electric throttle control actuator. Check the harness connector.
● Intake system vacuum leak. To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. At 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 valve and at the MAF for cracks or loose clamps.
● PCV system. It may be a bad valve or cracked hoses.

The P0138 condition can cause the ECU to produce an incorrect fuel mixture. Here are some possible causes:
● Harness or connectors (The sensor circuit is open or shorted).
● Heated oxygen sensor 2 is bad.


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## SACCITYAUTO (Mar 22, 2016)

have a mechanic look into see what the codes are and could be the air flow meter i have one for sale contact me


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