# 2011 Sentra 2.0 Stalls



## lasher15158 (Sep 2, 2017)

My 2011 Nissan Sentra will start......runs rough for several seconds and just dies. If you give it gas while it's running it runs smooth. Once you let off the gas, it starts idling rough and eventually stalls out.
Any ideas?


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## lasher15158 (Sep 2, 2017)

ok....so now the sentra starts and idles but when you give it gas it starts hesitating at about 4000rpms


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## rogoman (Dec 16, 2004)

The condition you're describing can be caused by a marginal crankshaft position sensor or a camshaft position sensor. If you're buying one or both of them, buy only OEM units from a new car dealer. Don't buy aftermarket types; they've been known to fail in a short time; some are even DOA. You can perform many of the diagnostic tests yourself which a dealer/private shop would do anyway. Here are the possible causes:

- Improper/dirty spark plug(s).
- Insufficient compression.
- Incorrect fuel pressure.
- Fuel injector(s) dirty or leaking.
- Intake system vacuum leak.
- MAF may be defective or dirty.
- Air fuel ratio (A/F) sensor 1 malfunction.
- The camshaft position sensor (CMP) or the crankshaft position sensor CKP) may be defective.

To properly diagnose dirty/leaking fuel injectors, they need to be remove and tested on a flow bench tester. You can also do a quick leak test by teeing-in a fuel pressure gauge to the fuel rail input, then turn the ignition switch to the "RUN" position without starting the engine. If the pressure drops off rapidly, one or more injectors are leaking.

How long have you had the old spark plugs? If they are very old, then it's time for a set of new ones. When replacing the plugs, examine the electrodes for telltail signs that might point to what the problem in the engine might be. Always buy OEM NGK spark plugs, not aftermarket types which can cause drivability problems.

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The fuel pressure can be tested as follows:
Tee-in a temporary fuel pressure gauge to the fuel rail input. The reading at idle should be approximately 51 psi.

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To test for an intake system vacuum leak, 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 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.


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