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I had the famous 240sx die at idle/hesitation problem where the car runs rich... floods.. hesitates and smells like gas. I belive I now understand exactly what caused it. BTW this is after ~900 in repairs and diagnosis from the dealer.

My first mechanic suggested I do a tune up including plugs and ditributor rotor/cap. Still stalling. He suggested that the CAT may be busted up and choking the exhaust. This all cost $650 and i realised that this guy is as useless as a tit afte suggesting the CAT since i had just passed emmisions inspections and told him about that.

Next I cleaned the AICV. Still stalling.

Next I took it to the dealer. They told me the MAF was slow and charged me $150 for diagnosis.

I belive my problem came from a dirty MAF mesh rather than a dirty MAF sensor foil. The sensor measures air velocity at one region in the cross section and, in the ideal, a measurement of the total airflow through the duct is deduced from that one sample area. In the real world that mesh will get dirty inconsistently and the flow will not be uniform. If the spot on the mesh is clean in front of the sensor element then flow readings will be incorrectly high, causing a rich condition that may eventually stall the car. I belive at Idle my engine was running so rich it was flooding. Also I think the mesh may be a flow straightner rather than a sensor guard. It might be there as a design feature to create a more accurate/precise instrument. In short the MAF is likley the most important sensor in an EFI so keep the mesh clean so the thing works properly. I have owned the car for 7 years. It has never run better/ smoother/ smoother throttle response as it does no simply for cleaning that friggin mesh. Hope this helps.
 

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I had the famous 240sx die at idle/hesitation problem where the car runs rich... floods.. hesitates and smells like gas. I belive I now understand exactly what caused it. BTW this is after ~900 in repairs and diagnosis from the dealer.

My first mechanic suggested I do a tune up including plugs and ditributor rotor/cap. Still stalling. He suggested that the CAT may be busted up and choking the exhaust. This all cost $650 and i realised that this guy is as useless as a tit afte suggesting the CAT since i had just passed emmisions inspections and told him about that.

Next I cleaned the AICV. Still stalling.

Next I took it to the dealer. They told me the MAF was slow and charged me $150 for diagnosis.

I belive my problem came from a dirty MAF mesh rather than a dirty MAF sensor foil. The sensor measures air velocity at one region in the cross section and, in the ideal, a measurement of the total airflow through the duct is deduced from that one sample area. In the real world that mesh will get dirty inconsistently and the flow will not be uniform. If the spot on the mesh is clean in front of the sensor element then flow readings will be incorrectly high, causing a rich condition that may eventually stall the car. I belive at Idle my engine was running so rich it was flooding. Also I think the mesh may be a flow straightner rather than a sensor guard. It might be there as a design feature to create a more accurate/precise instrument. In short the MAF is likley the most important sensor in an EFI so keep the mesh clean so the thing works properly. I have owned the car for 7 years. It has never run better/ smoother/ smoother throttle response as it does no simply for cleaning that friggin mesh. Hope this helps.
Thanks you for the post.
 
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