Rpm’s fluctuate at idle, car shakes, and shuts off. Goes into limp mode, and is hesitant to accelerate, Check engine light has been on throwing a code for a mass airflow sensor, I have replaced the MAF and that is NOT the issue.
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Hi Brett,
The MAF measures the amount of air flowing from the air filter to the engine to determine the correct fuel to air ratio. The two main possibilities I see here are that a) your replacement MAF is defective (which has happened to me), or b) you may have an air leak between the MAF and the intake manifold.
Couple of things I'd try first would be to unplug the MAF and see if your issue goes away. When the engine computer doesn't get a signal from the MAF it defaults to preset readings based on other factors such as RPM and throttle position. It will still run reasonably well, just not quite as efficiently when it has a MAF reporting the actual airflow. If it stops misbehaving with the MAF unplugged, then you've almost certainly gotten a bad part and replacing it (again) should fix the problem.
Otherwise, check the air duct between the MAF and the manifold for any cracks or leaks; if there are it'll be letting in extra air that the MAF wasn't accounting for and throw off your air/fuel ratio.
Give those things a try and let us know what you find.
P.S., Another thing just occurred to me; when my 1999 Beetle's MAF was misbehaving, I found that the plug that connected to the MAF had deteriorated to the point where I wasn't getting good electrical connections, so check your plug for pushed in, broken or missing pins and any signs of corrosion on the pins, along with the wires themselves for breaks or frayed spots.
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Hi,
I realize that you have replaced the MAF sensor but perhaps the problem is with the MAF sensor circuit.
Here are images from the relevant section of the service manual for your model that describe how and what to test when there are MAF sensor DTC codes.
(click on images)
Note: Ref EC-447 mentioned in image #2 is shown in image #4.
Hopefully this is of some help.
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you have a hole in the air intake boot(big black hose that connects your air filter to the throttle body) which is letting un-metered air in the motor causing the check engine light on and limp mode, and the code is most likely po171(lean) or a code relating to your airflow meter(MAF Sensor) reading out of range, erratic.etc...... unplug your airflow meter and the computer will recognize that it's missing and will make adjustments to injector pulse/fuel trim, ignition timing, possibly variable valve and/or camshaft timing, and any other performance adjustments i'm forgetting by calculating air intake volume based on readings from your TPS, ECT, A/F Ratio and/or O2 sensor(s) and ANY OTHER SENSOR i'm forgetting. It's also possible that i'm a professional bullshitter and just spent all that time making up everything i just typed here!Nope! From your description it sounds like what i said, a hole in the air intake boot causing too much air into the motor for the ECU to compensate for by adding fuel(if the ECU could read how much air it is!) you can, A; unplug your vehicle's Mass Air Flow Sensor pigtail connector, or, B; visually locate and verify a crack/tear/hole allowing air to enter without being accounted for, and then get a roll of good quality Duct Tape(preferably black colored Gorilla Tape) and carefully wrap the intake boot to seal the air intake leak. i use black duct tape due to income deficiencies i have so the tape will be there for an extended amount of time- which is until it fails, and then will get a fresh rewrapping of black duct tape!
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2 commentaires
Hi,
What is the model year of the vehicle and what DTC code number is being shown by the OBDII scan?
par jayeff
2015 Nissan Sentra SR, I don’t know the code number, just that it reads as a mass airflow sensor on a diagnostics check
par brett roberts