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post #1 of 4 (permalink) Old 12-13-06, 09:30 AM Thread Starter
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Question 5.0 running rich

hi all
I've got a 94 mustang GT and it's running so fat that it makes my eyes water!
I threw the scan tool on it to check the sensor outputs and the 02 sensors are both pegged as rich. the odd thing was, when I ran a custom stream the coolant temp sensor was reading 1800 deg F, when I ran the standard datastream it was reading 171 deg F.
I used to get about 400km to a tank, until I replaced the fuel pump (due to hard start) and now I'm only getting about 325km. I've also recently done a tune up (just plugs/wires/cap/rotor/fuel filter). the engine is completely stock except for the K&N cold air intake.
with gas prices the way they are these days this car is killing me! if anyone has any ideas how to solve this problem I would appreciate it! I recorded the stream, so if any other details from it would help I can post them up here.


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post #2 of 4 (permalink) Old 12-13-06, 07:47 PM
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Re: 5.0 running rich

From what you've detailed, my first thought would be perhaps the fuel pressure regulator has gone bad. If you can get your hands on a fuel pressure gauge, check it out. It should be in the low-mid thirties. If it is bad, an aftermarket regulator and gauge can be had for fairly reasonable prices from several sources.

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post #3 of 4 (permalink) Old 04-06-07, 09:36 PM
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Re: 5.0 running rich

I have the same problem in my 1994 mustang but I'm allso reading a code for the transmision oil tempeture sensor.... My car runs ok at regular speed but when I florit It doesnot aselerate like it should...... it doesnot eaven pillout....
does your car do the same......
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post #4 of 4 (permalink) Old 04-07-07, 01:21 PM Thread Starter
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Re: 5.0 running rich

no mine performs fine, and I have no other codes. I've replaced the coolant temp sensor and both o2 sensors and everything else is in spec. I think it's a computer problem - my car KNOWS it's running rich, but isn't doing anything to correct it.
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