posted 01-20-2004 06:08 PM               

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Any help to the possible cause would be greatly appreciated. Thanks for any help. My vehicle is a 1998 FORD F-150 4.6 LITER 60,000 MILES
PINGS ON RAPID ACCERATION. HOT OR COLD.
RAN ENJECTOR CLEANER THROUGH FUEL TANK
CHANGED FUEL FILTER
CLEARED CODE. CODE RETURNED AFTER ABOUT 150 MILES.

[This message has been edited by Busman (edited 01-21-2004).]

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posted 01-20-2004 08:44 PM            

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There's air getting into the number 1 bank either before or after combustion.

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posted 01-22-2004 10:47 AM               

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You need to get the Long Term Fuel Trim value. This will enable you to definitely determin if you have an air leak or possibly the oposite, rich mixture.

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posted 01-22-2004 06:48 PM               

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quote:

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Originally posted by marvinshos:
You need to get the Long Term Fuel Trim value. This will enable you to definitely determin if you have an air leak or possibly the oposite, rich mixture.

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I am not clear on the long term fuel valve. How is this obtained? Thanks for your help.

[This message has been edited by Busman (edited 01-22-2004).]

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posted 01-23-2004 10:38 AM            

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quote:

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Originally posted by Busman:
[B] I am not clear on the long term fuel valve. How is this obtained? Thanks for your help.

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I don't know where marvinshos gets this idea you could have a rich condition.
The pinging can be from a lean condition.
Do you have a scan tool? If you can only read codes you won't be able to give me much help. Look for vacuum leaks or exhaust manifold leaks on that side. Spray carb cleaner around the intake on that side and see if the engine changes idle. If it does you found your leak.

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posted 01-23-2004 11:04 AM               

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Im convinced that P0171 also occurs in California emission System cars having Air/Fuel Ratio Sensors(in lieu of O2 Sensors.

My '97 Camry (4 Cylinder) had a P0171 DTC along with a -11% Long Term Fuel Trim. Unfortunetly I never found the cause, as the DTC cleared itself before I could get all the data.

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posted 01-23-2004 02:00 PM            

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There is not really anything special about California vehicles except that they usually have an extra catalytic converter slapped on them. A/F ratio sensors are all over everywhere. They function slightly differently but the fuel control mechanisms are exactly the same only more precise.

I have seen "system too lean" codes where the LTFT was subtracting fuel (negative %) but it was on a turbocharged car with a major vacuum leak (after the turbo) fuel trims were all over the place (positive and negative) due to the turbo and location of the leak.

Like carfixer says P0171 usually means air is getting in somewhere and leaning out the mixture.

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