O2 sensor question

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Nov 15, 2003 | 08:17 PM

MunsterGarage

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Joined: Oct 2003

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From: Central New York

O2 sensor question

When an 02 sensor is failing, what are some of the things to expect?

Nov 16, 2003 | 06:44 PM

1987rangerpu

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Joined: Oct 2003

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the o2 sensor in my 87' ranger was gone and when replaced it got better mileage and almost actually passed the Ma emissions test.

Nov 16, 2003 | 06:55 PM

1ruralmailman

Mountain Pass

Joined: May 2003

Posts: 117

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From: upstate new york

usually 5-7 mpg of mileage goes away over night,strangely enough the seem to run a little smoother .ithink this has to do with the computer going full rich to keep you from melting down.

Nov 18, 2003 | 03:09 PM

gatesj

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From: Remsen, NY

Even a marginal sensor will make the mixture richer. When they're working normally, they show low (0-0.5v) voltage for lean running and higher (.5-1v) voltage for rich running. When they start to fail they make less voltage and the computer thinks the engine's running too lean, so it enriches a little to compensate.

Nov 19, 2003 | 05:39 AM

Supercab

Lead Driver

Joined: Feb 2000

Posts: 5,374

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From: Palm Bay, Florida

Could an O2 sensor thats going bad cause the computer to make the engine run so rich that it will act flooded upon a warm re-start? I think thats what might be causing my hard starting trouble.

Nov 19, 2003 | 07:27 AM

gasman6674

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Joined: Apr 2002

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From: Greenwood In. USA

I had a bad distributor cap cause that problem. I thought my injectors were dirty and leaking. I started fine in a cold start but acted like it was flooded when warm
Its a 92 302 BTW

Nov 19, 2003 | 08:39 AM

m14dan

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Joined: Nov 2003

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The o2 sensor is out of the loop when you are starting so I doubt it could cause that. On mine especialy since it only has 1 o2 sensor I treat it as part of a tune up. It gets replaced every 60,000 along with the cap, rotor, plugs and wires. I don't take any chances with parts failing so I do it by the book. Also use only ford parts with a very few exceptions. The oxygen sensor is made by bosche wich you can get at autozone a lot cheaper.