Engine Fault Codes?
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Joined: Jun 2004
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<TABLE width="100%" border=1><TBODY><TR><TD class=ital width="10%">P0171</TD><TD width="90%">System Too Lean - Bank No. 1</TD><TR><TD class=ital width="10%">P0172</TD><TD width="90%">System Too Rich - Bank No. 1</TD><TR><TD class=ital width="10%">P0174</TD><TD width="90%">System Too Lean - Bank No. 2</TD></TR></TBODY></TABLE>
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Joined: Jul 2002
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From: Long Island USA
Lean bank is a vacuum leak, leaky intake tubing, anything adding more air AFTER the MAF. Or, possibly a dirty/faulty injector - check the simple things first, cracked intake hose, PCV hose, bad PCV valve?
Also, I've had a '96 t-bird 4.6L with OBD II throw the Bank 1 lean code with a dirty MAF - take out the air cleaner, look down the tube at the MAF wires. If they are WHITE they are clean, if they are grey or darker they are dirty. Clean 'em up, and the MAF will start registering the correct amount of air (dirty will tell the computer less air, which is wrong, so the computer will see the engine running lean at the O2 sensors).
Seen cars with stock air filtes with dirty MAF's after only 20K miles... (GM, but hey...)
Also, I've had a '96 t-bird 4.6L with OBD II throw the Bank 1 lean code with a dirty MAF - take out the air cleaner, look down the tube at the MAF wires. If they are WHITE they are clean, if they are grey or darker they are dirty. Clean 'em up, and the MAF will start registering the correct amount of air (dirty will tell the computer less air, which is wrong, so the computer will see the engine running lean at the O2 sensors).
Seen cars with stock air filtes with dirty MAF's after only 20K miles... (GM, but hey...)
Fleet Mechanic
Joined: Apr 2001
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Originally Posted by krewat
Lean bank is a vacuum leak, leaky intake tubing, anything adding more air AFTER the MAF. Or, possibly a dirty/faulty injector - check the simple things first, cracked intake hose, PCV hose, bad PCV valve?
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Junior User
Joined: Mar 2004
Posts: 56
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From: central coast of californ
thanks for the help
I want to thanks all of the respondants. It turned out to be a vacuum leak in the pcv hose. I fixed it and all is well. Thanks again, Wayne
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