1988 Bronco II surges, loss of power, intermittent. | Ford Explorer - Ford Ranger Forums - Serious Explorations

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1988 Bronco II surges, loss of power, intermittent.

89Bronco

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1989 Bronco II
Hello all. I have a 1988 Bronco II 4wd auto with 2.9 that I just bought. It was running fine, then it has developed a intermittent miss, loss of power, and a surging, all while holding the accelerator steady, then it will lunge forward with a burst of power, then revert to the loss of power, almost seems like a stuck choke, but it is fuel injected. It idles fine. Fresh tune-up, map sensor, throttle sensor, fuel filter, oxygen sensor all new. My mechanic is puzzled, as the scanner says the oxygen sensor is bad, but it is new. We are at our wits end. What can we try next? Thanks in advance.
 
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Twiztid

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most likely the TFI module or bad pick-up in the dist. have had that problem on a few 2.9's before
 
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janderson4010

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third boxcar, midnight train
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MrShorty

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as the scanner says the oxygen sensor is bad,
I'm guessing by this you mean that he pulled codes, got an O2 sensor code, and, from that alone, decided the O2 sensor must be bad.

I know I'm inferring/assuming a lot here, but I'd make sure you've fully diagnosed that O2 sensor code. If you've replaced the O2 sensor and are still getting the O2 sensor code, that suggests to me that something else in fuel control/engine management is at fault. Have you checked fuel pressure (when it is stumbling)? Fuel pressure test is usually the first test listed for O2 sensor codes by the book.
 
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89Bronco

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Sorry, forgot to say we tried a new TFI, and it didn't change anything. Will try the distributor pick up Monday. Will keep you posted. Thanks!
 
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89Bronco

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Will also pass on the info about the fuel pressure to my mechanic. Thanks!
 
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janderson4010

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I'm guessing by this you mean that he pulled codes, got an O2 sensor code, and, from that alone, decided the O2 sensor must be bad.

I know I'm inferring/assuming a lot here, but I'd make sure you've fully diagnosed that O2 sensor code. If you've replaced the O2 sensor and are still getting the O2 sensor code, that suggests to me that something else in fuel control/engine management is at fault. Have you checked fuel pressure (when it is stumbling)? Fuel pressure test is usually the first test listed for O2 sensor codes by the book.

you would hope so
 
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89Bronco

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Okay, replaced the module in the distributor, seems to work well, except still get the same problem very intermittently. It almost seems that if I drive it real easy, it runs fine, but if I make a hard turn coming out of say, a driveway, it will sputter and load up again, but if I throw it in neutral and idle it up a little, it clears up.
 
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janderson4010

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my BII did the same thing only waaaay worse, turns out my o2 sensor wires had contacted the exhaust and melted together. so my fuel air mixture was all screwed up. thus when I started up and it was warming up it ran fine but as soon as it warmed up and started trying to adjust the fuel air mix it would barely run and die all the time.
 
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blindtoe

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Fuel pressure regulator. Check the fuel pressure
 
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