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Category: Ford
Satisfied Customers: 26615
Experience:  ASE CERTIFIED TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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2000 ford: liter..gas engine..Runs rich on Bank 1 and on bank

Customer Question

2000 ford crown vic, 4.6 liter FI gas engine. Runs rich on Bank 1 and on bank 2. Any ideas
Submitted: 10 years ago.
Category: Ford
Expert:  AMEDEE replied 10 years ago.
I would check the fuel pressure regulator. It is located on the fuel rail. It is round, about a quarter size and has a vacuum line going to it. If the regulator is leaking gas than it can cause this problem. Pull off the vacuum line that goes to the regulator. Be absolutely sure there is no gas in the vaccum line. If there is, the diaphram has ruptured and there is gas entering the engine that is not accounted for and the regulator will need to be replaced!
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Customer: replied 10 years ago.
Reply to AMEDEE's Post: I already tried that, there is no gas in the vacuum line.
Expert:  AMEDEE replied 10 years ago.
There could very well be an injector leaking gas on that bank. I would rec to hook up a fuel pressure gage and turn the key on to prime the pump. The gage will go up and should remain steady. If the pressure is dropping down, than one of the injectors could be leaking. You would just have to pinpoint which one by pulling the fuel rail up to see which one it is.
Customer: replied 10 years ago.
Both banks are running rich. When the check engine light comes on, it trips two codes. One for the left bank and one for the right. I would not think that I would loose injectors on both sides at the same time.
Expert:  AMEDEE replied 10 years ago.


You could have a bad mass air flow sensor. This is a very important sensor input to the computer. It uses a hot wire sensing element to measure the amount of air entering the engine. The MAF sensor then outputs an analog voltage signal to the PCM proportional to the intake air mass. The PCM calculates the required fuel injector pulse width in order to provide the desired air/fuel ratio. If the sensor is bad than this air/fuel ratio will be off causing severe performance issues. In extreme cases, I have seen these two problems cause a no start condition. This can be bad both ways over or under estimating air flow into the engine which can result in a lean or rich condition.

Customer: replied 10 years ago.
I will replace it and let you know! Thanks.
Expert:  AMEDEE replied 10 years ago.

I would rather have you check if first.

If you need help, let me know.

I would also like you to check fuel pressure. If the return line is kinked or there is some obstruction, fuel pressure could be way to high and cause your rich condition.

Customer: replied 10 years ago.
Reply to AMEDEE's Post: How do I check the air mass?
Expert:  AMEDEE replied 10 years ago.
What is the eighth digit of the vin?
Customer: replied 10 years ago.
Expert:  AMEDEE replied 10 years ago.

First start by checking the voltage with a volt meter.

Mass Air Flow Sensor

Key-On-Engine-Off 0.0-0.2 V

Idle 0.6-0.9 V

Customer: replied 10 years ago.
12 volts key on, terminal A on connecter.
Expert:  AMEDEE replied 10 years ago.
Good! GO to the signal wire and check voltage coming back to the pcm with the key on.
Customer: replied 10 years ago.
Your going to have to get a bit more specific on that one. Sorry.
Expert:  AMEDEE replied 10 years ago.
Well I can if you want. There is some more specific tests to run with more advanced tools than you most likely are willing to pay for. Normally I don't do this. I don't like to just replace parts, but under these circumstances i guess we can if your willing to do so. Go ahead and replace the mass air flow sensor. Just don't get mad at me if that does not take care of your problem. Remember, I am just trying to help you.
Customer: replied 10 years ago.
No problem.
Expert:  AMEDEE replied 10 years ago.

You will have to clear the computer by disconnecting the battery for 2 minutes.

Also, sounds weird, but, when you get it all back together. do a few Wide open throttle runs from 0 to 60. THis is how the ford engineers update the Baro pressure in the computer. WIDE OPEN THROTLE. Because the mass air flow sesnor is i control of the baro pressure you will have to run this procedure after you get the new mass air flow sensor in.