My truck keep falling deed at stop sign and red light i change the crankshaft ckp sensor but im still having the same problem with it doind the same thing need urget help.

autodr

• 260 Answers
• Posted on Nov 15, 2008

SOURCE: Cleaning the Mass Air Flow Sensor

i will try to help. 171/174 indicates lean condition in engine. the mass air flow sensor is located in the rubber tube going to throttlebody. you can try to clean it. using mild carb cleaner safe for sensors, remove sensor from tube. spray clean the tiny wires located in the cylinder. do not touch them, they are very delicate. these engines are also notorious for leaking intake gaskets and faulty pcv valves. these will all set these 2 codes. feel free with anymore questions.

Harvey N Tawatao

• 3854 Answers
• Posted on May 01, 2009

SOURCE: PO174 HOW TO CLEAR THE CODE

Okay so the more oxygen in the exhaust (lean condition) the lower the voltage from the O2 sensor and the more fuel the computer calls for. Then the oxygen content in the exhaust drops (because it is being used up in the combustion process), and the voltage increases (rich condition) and the process repeats, for as long as the car is running, hundreds of times a minute. A gasoline internal combustion engine needs oxygen to burn the fuel. If the mixture is ideal (or 14.7:1) then all of the oxygen is consumed as the fuel is burned. The exact amount of fuel needed to produce a 14.7:1 air/fuel ratio varies with barometric pressure (altitude), relative humidity and fuel quality and condition; thus the need for oxygen sensors.

So knowing all of this what should we check when we have those pesky rich or lean codes? The most common issues for lean codes are:

1. Vacuum leaks - check for failed or loose vacuum lines, leaking intake gaskets, intake air tubes loose or any other source of un-metered air leaks (leaks after the Mass Air Flow Sensor) 
2. Restricted fuel filter or bent/pinched fuel system lines 
3. Incorrect input from other sensors, such as the Mass Air Flow Sensor, which may not always drop a separate code 
4. Engine misfire – Yes I know this one may seem weird. You might think that if there is a misfire then you will have all that unburned fuel and it should read rich; right? Well the O2 sensors read only oxygen content in the exhaust, so if you have all that unburned fuel from incomplete combustion then, you guessed it, you also have all that unburned oxygen. High O2 content in exhaust equals a lean reading!

There are also some other possibilities such as an internally leaking EGR system, (but this will typically set a separate code). A leak in the exhaust system before the O2 sensor will also cause incorrect readings. And always check for after- market modifications. These can throw a wrench into the works! The only other possibilities (however unlikely), are wiring issues, computer concerns or a bad O2 sensor!

P0174 is a Lean condition on the side of the engine where cylinder # 2 is. Good luck and hope this helps.

SOURCE: 2001 ford mustang service engine light on

IT ALMOST SOUNDS LIKE YOU MAY HAVE A VACUUM LEAK SOMEWHERE. USE A LENGTH OF RUBBER HOSE AND HOLD IT UP TO YOUR EAR TO PIN-POINT THE LOCATION OF A VACUUM LEAK. HOPE THIS HELPS. LET ME KNOW PLEASE. THANK YOU IN ADVANCE FOR AN HONEST RATING AND THANKS FOR USING FIX-YA. P.S. EGR VALVE IS VACUUM ACTUATED

SOURCE: 2003 Ford Taurus stalls at idle

go to autozone.com and register for free. You will then have a full free online repair manual with step-by-step directions, diagrams, troubleshooting, testing, replacing, and more. As an automechanic myself, this a wonderful site.

SOURCE: location of mass air flow sensor

The sensor is mounted on the throttle body between the air cleaner assembly and the air cleaner outlet tube.


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