I have an 86 with about 280,000 miles on it. Over the last few months my gas mileage has declined drastically. My odometer doesn't work, but I would have to say it gets maybe 17 miles per gallon. I have had an 87 with well over 300,000 miles on it get 30-33 miles per gallon. I have done plugs, distributer cap, rotor button, fuel filter all with no improvement. When it first cranks, it won't idle well till it warms up. It sometimes dips to about 200rpm then picks up to 1200rpm. It idles erractically like that for a few minutes. What could possibly be wrong to make mileage be soor poor? Bad injectors, AFM, TPS, fuel pump, anything. Any advise anyone can offer will be much appreciated. Thanks.
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I'd guess that your idle valve is bad, but you most probably have a vacuum leak somewhere. This can make the idle real bad and severely increase the fuel consumption as the ECU is trying to compensate for the high volumes of air by injecting more and more fuel.
But, it could be many more things as well. Bad injectors, damaged camshaft/rockers and AFM are a few to name.It's not an old car. It's an old friend. -
My '87 325es has been doing the same thing, practically. Bad idle at start, but, when she warms up it purrs.Comment
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bad mileage
check
- air filter?
- o2 sensor --> use the mustang 5.0 one, they are cheap to replace.
- throttle body?
- vacuum leak -specifically PCV tube
- injectors
- ICV
- coolant temp sensor.
If your maf is bad I would think you would have bad idle or poor drivability constantly.Comment
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