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Nissan Sentra 2001 stalling at idle, gets "stuck in low rpms" and low power at low rpm's

My families 2001 Nissan sentra often stalls at stoplights, has low power sometimes in the low rpm’s and sometimes (though not always) chugs/jolts a bit at low rpms and has trouble “overcoming” that window and getting more power. If I give it more gas the engine seems to get “normal” at around 2500 or 3000 rpm’s and then is fine.

We took it in and the mechanic said it was a bad O2 sensor or MAF sensor… can’t remember which. We tried replacing the MAF sensor but it still has the problem. We have heard that we may need the computer re-set somehow or made to recognize and sync up with the new part. As we call around this is very expensive just to make a part that is already installed work. Is this necessary? What’s the next, cheapest, step. Thanks!

I found a couple recalls affecting that year for a “deffective crank position sensor” that supposedly produce my cars symptoms. Any tips for determining if that is the issue and for cashing in on the recall?

Make an appointment with Nissan dealership.

RECALL: 2000 - 2003 Nissan Sentra
NHTSA Campaign Number: 03V455000
www.nhtsa.dot.gov

Manufacturer NISSAN NORTH AMERICA, INC.
Recall Date: 11/17/2003
Potential Number Of Units Affected: 630000
Description ENGINE AND ENGINE COOLING
Summary ON CERTAIN PASSENGER VEHICLES, THE CIRCUIT BOARD FOR THE CRANK POSITION SENSOR MAY HAVE AN IMPROPER SOLDER JOINT DUE TO SOLDER DEFORMATION CAUSED BY HEAT STRESS ACCELERATED BY THE EXISTENCE OF FLUX RESIDUE DURING THE SOLDERING PROCESS.
Consequence THIS COULD CAUSE THE “SERVICE ENGINE SOON” WARNING LIGHT TO COME ON, CREATE A NO START CONDITION, CAUSE REDUCED ENGINE POWER, OR CAUSE THE ENGINE TO STOP RUNNING WITHOUT WARNING DURING VEHICLE OPERATION, WHICH COULD RESULT IN A CRASH.
Remedy DEALERS WILL REPLACE THE CRANK POSITION SENSORS. VEHICLES INVOLVED IN A PREVIOUS RECALL CAMPAIGN, 01V357, ARE ALSO INCLUDED IN THIS NEW CAMPAIGN. THE REPLACEMENT SENSORS USED IN THAT CAMPAIGN ARE ALSO AFFECTED. OWNER NOTIFICATION BEGAN ON DECEMBER 22, 2003. OWNERS SHOULD CONTACT NISSAN AT 1-800-647-7261 OR INFINITI AT 1-800-662-6200.

If the above isn’t the problem, another likely cause is an air leak that is allowing unmetered air through, bypassing the MAF. This causes a lean fuel mixture, especially at idle and low speeds.

If the car idles roughly, and stalls when you put it in gear, an overly lean mixture is a likely cause. The first place I look when this happens on my cars – neither is a Nissan – is leaky vacuum hose and vacuum devices. Often a quick visual inspection of the vacuum hoses will spot a cracked hose or something like that. If not a hose, then it might be a leaky device, which I can find with a hand held vacuum pump & guage. If it is a cracked hose, usually it leaks right where the hose connects to a connector.

Your mechanic-- if he already did the inspection of the vacuum hoses and devices – isn’t wrong, as faulty O2 sensors and MAFs can cause this symptom too, as can a variety of other problems, but more often than not in my experience I’d expect some kind of air leak.