Mechanics

MAF

2003 Ford Ranger

Engine Mechanical problem
2003 Ford Ranger 6 cyl Four Wheel Drive Automatic 97000 miles

i have codes p0171 and p0174 I know that these 2 codes together most of the time mean maf is bad but I cat tell I cleaned my maf with maf cleaner changed my air filter chnged my plugs and wireset and fuel injectors but when I idle at a stop or red light my trucks feels like its about to die it will get low rpms and shake but just a little. My truck has never stalled out and when I drive it works great its only when im stoped in gear. Please help me with this problem.
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Mjrambo
April 19, 2009.




Hello,

Here are some other things to check.

Fuel Filter and fuel pressure.

Check for Vacuum Leaks and check the IAC.

Here is more on the MAF.

Your engine is designed to run on specific values, if there are no codes besides a lean mixture code and the engine is running ok the problem is a sensing value problem. A MAF (mass air flow) sensor is famous for causing such a problem. Example: Let's say the engine is running at 2100 RPM at any particular time. When a MAF fails it sends feedback information to the ECM/PCM that the engine is running at 1800 RPM so the computer will lean down the mixture. But the engine is running at 2100 rpm so the mixture is detected lean by the oxygen sensor and the computer will illuminate the CEL (check engine light). There are a few main reasons the MAF reading can be incorrect. First the air intake boot could be cracked or ripped allowing non-metered engine air intake to be consumed. Or the MAF fails because the sensing element inside the sensor becomes contaminated from impurities from the air the engine consumes. Sometimes this element can be cleaned with an aerosol cleaner such as carburetor cleaner. I have had limited success cleaning the MAF sensor, replacement at this point is best. Repair or replace failed components as needed and recheck the system.

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Obxautomedic
Apr 19, 2009.


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