I Got This 1996 Mustang Gt, It Is Throwing 3 Codes, And Can't Idle For Crap. Sometimes Shuts Off. Here Are The Codes. If Anyone Can Help, Please Do.

P0174
P0401
P0171

Thanks

 

P0171 System Too Lean - Bank No. 1.
P0174 System Too Lean - Bank No. 2.
P0401 Insufficient EGR Flow.

[hr]
A Ford P0171 is a LEAN code fpr cylinder bank 1, and P0174 is a LEAN code for cylinder bank 2. These codes commonly occur on many Ford vehicles, and are set when the powertrain control module (PCM) sees the air/fuel mixture is running too lean (too much air, not enough fuel).
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P0401 - EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.

A code P0401 most likely means one or more of the following has happened: [ul][*]The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced[*]There is a blockage in the EGR (tube), most likely carbon buildup[*]The EGR valve is faulty[*]The EGR valve may not be opening due to a lack of vaccuum[/ul]

 

to fix the P0171/P0174 you need two new o2 sensors, (Fronts - controls A/F Ratios)


In fixing the P0401 code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit. [ul][*]Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open[*]Clean out the EGR valve and/or tubing to remove deposits[*]Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)[*]Replace the DPFE sensor (with a good quality / OEM one)[*]Replace the EGR valve[/ul]

 

Goodluck and hopefully that helps :] its all a very simple fix!

 

I don't have a repair manuel to review where the parts are. I am sure I can figure it out though. Also, could i be a possible vacuum leak? If so, how can I find it?

Thanks,

Jason

 

it could be a vaccum leak for the idling problems but your computer threw that code off for the EGR flow soo i doubt that its a vaccum leak.

if you need a repair manual heres an online version...

http://search.ebscohost.com/
username: greatfalls
password: publiclibrary

then you just insert your application (your car info) and then there you go, you have an online version of Hayne's repair manual

 

O2 sensors are probably the easiest to repair, since it just takes a wrench to unscrew it out and then you slap on the new ones. and you would get the ones cloest to your motor, on the "bend upward" part of the midpipe.

 

Man, thank you so much for all the help. As far as the vaccum pump, what should I use?

Thanks,

Jason