94 351 Surging
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Joined: Sep 2004
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94 351 Surging
My 1994 351 Bronco surges a low speeds...Any ideas, tune up done all seems well, also new tranny but has been surging for a while now...do not notice at high speeds just below 45-50 or so really notice at about 30....
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Joined: Oct 2005
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My best guess is one of two things.
1. You're probably getting unmetered (aka free air) some place in the intake system after the air flow sensor. That can make the O2 sensor think you have a lean condition which it richens to compensate, then the air flow meter again tells the computer to lean the mixture out again, and the two sensors seesaw the mixture back and forth. This problem is somewhat common after a tune up, mechs sometimes don't get all the intake hoses tightened up properly.
2. If the surging isn't cured by hose tightening, then I'd suspect your O2 sensor. You can test it, the methods have probably been discussed out here several times, but the best thing is to replace it, on a Ford if you shop wisely, you can buy a new one for less than $70.00.
Pat
1. You're probably getting unmetered (aka free air) some place in the intake system after the air flow sensor. That can make the O2 sensor think you have a lean condition which it richens to compensate, then the air flow meter again tells the computer to lean the mixture out again, and the two sensors seesaw the mixture back and forth. This problem is somewhat common after a tune up, mechs sometimes don't get all the intake hoses tightened up properly.
2. If the surging isn't cured by hose tightening, then I'd suspect your O2 sensor. You can test it, the methods have probably been discussed out here several times, but the best thing is to replace it, on a Ford if you shop wisely, you can buy a new one for less than $70.00.
Pat
