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Lean code= O2 sensor sees too much unburned air. Could be caused by a unmetered air leak (vacuum leak) but you would most likely run rough at idle and better at rpms. It could mean you are not getting enuf fuel to burn the air, fuel pump weak (my first guess) or dirty clogged injectors (again unlikey as you run well up to a certain load) OR the VAF (it measures the amount of air you take in to the engine via how far the flappy door moves) has a sticky flappy door. All this has been stated before, i am just a post whore. I would second everything IceDawg said. And replace your O2 because you probably need to anyway.
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Going old school...
89L Carby FIDO, previously owned by FestivaFred -
Make sure you have no cracks in your intake tubingFord Fester
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^^ and worn mounts letting the cracks open a little when you get violent with the throttle!
Make sure the tps is not stuck too, although the vaf is more critical, make sure every thing that should move to let the ecm know you just dumped air in does in fact report that!Reflex paint by Langeman...Lifted...Tow Rig
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Wow lots of great info here. As of now I took the maf out and the flap moves fairly easy. It feels like its spring loaded to close but it to move easily when I press it. How do I test the coil for arcing?Comment
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Is your CEL on constantly or only when you rev the engine?Daily Driver:
91 Red Ford Festiva L 5spd Stock
Show Car:
2004 Black Premium Mustang GT ConvertibleComment
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When I start the car the check engine light comes on after about 2-3 seconds and remains on no matter if I rev it or not. Its like its in what I like to call "limp home mode" dumping extra fuel to comensate for the lean condition so the engine isnt damaged.Comment
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Well distributor, and wires replaced but problem persists. Im thinking weak fuel pump or bad fuel pressure regulator, which is more likely the culprit? Like I said it idles fine and runs fine with light throttle, but as soon as I get on the gas it falls FLAT on its face.Comment
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Have you changed the fuel filter? I had a Nova that when the fuel filter clogged it would give symptoms like you are describing.Jerry
Team Lightning
Owner of Team Lightning
90 L "Peewee" B6D. Bought new May 16,1990
92 L Thunder BP G5M-R Turbo B6T electronics. Jan 2016 FOTM winner SOLD
93 L Lightning. BP
Not a user of drugs or alcohol, Just addicted to Festiva'sComment
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yup fuel filter has also been changedComment
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