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Discussion Starter · #1 ·
My stang has 6 error codes 29,31,66,87,95,96. Have looked these up oline and it tells you what they are but not where to go to fix. 87,95,96 are fuel pump circuit prbloms. does that mean its a wiring problom and not the pump. main prblom is car wont idle right, sometime it does and sometimes not. HELP me please
 

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First question - what have you been doing?
Multiple codes often indicate poor harness connections. Had lot's of stuff unplugged, or maybe the EEC connection?
29 - VSS input low
31 - EVP ckt below min V
66 - MAF signal low (less than .4V last warm up) - or - TOT sensor output was less than Self-Test minimum value of 0.15 volts
87 - Fuel pump primary circuit failure. When the FP relay was activated by the EEC, voltage was not detected on the control circuit. -or - Voltage was not detected on Fuel Pump Monitor while the engine was running.
95 - Fuel pump secondary circuit failure. (The EEC senses infinite resistance to ground from the fuel pump on the Fuel Pump Monitor circuit.)
96 - Fuel pump secondary circuit failure. (The EEC did not sense battery voltage on the Fuel Pump Monitor circuit.)

Start here:
Mustang FAQ - Engine Information
 

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Discussion Starter · #3 ·
I haven't unpluged anything. the last problom I had with the car was the idling was the "idle control motor. and plugs and wires. also had code air management cercuit # 2 don't know what that is eathier.
 

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Okay...how are you at wire diagrams?...the one's in that link are coloured, and easy to follow.
Anyway...except for the VSS code, you're showing a common problem in the circuits from EEC pins 37/57 (voltage out) and for fuel pump alone, pin 22 (relay control ground).
What year model, and do you know how to manually clear the codes?
 

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You can clear the codes if you have a reader/scanner, or you can use a jumper wire:
Look at the top right of this diagram http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif , see the "Self Test Connector" and "Self Test Input" plugs?
1. Jump from "46" on "Self Test Connector" to "Self Test Input".
2. Turn key to "run" (don't start engine).
3. When check engine light (MIL) starts to flash codes, pull the jumper out and the EEC will go into "clear codes" mode.
 

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Oh, fuel pump isn't that hard to replace.
Uh, just though of something...you have a hatchback?
Raise up the carpet/mat back there and see if the fuel pump/sending unit harness has been mashed/damaged.
 

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I just ran my codes and I am having some of the same problems... Right now my car wont go over 3500 rpms... when i reach that point it starts to tach out like a rev limiter kicks in. the running codes that i get are 33,94,44. The codes i get with the key in the on position is 81,82,85,84, 22, 33,95. I know some of these are smog codes but i am not running cats or smog pump
 
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