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Old Oct 22, 2004 | 09:41 AM
  #1  
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Idle Surge

My 1991 Bronco is surging. I replaced the Idle Air Control...still surges.

Any help would be appreciated.
 
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Old Oct 22, 2004 | 09:51 AM
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Maybe a vaccuum leak?
 
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Old Oct 22, 2004 | 09:57 AM
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What do you mean by idle surge? I know when I first turn my 1990 bronco on it revs itself up to about 2000 then it finally settles down to 800. Is this an idle surge?

Kyle
 
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Old Oct 22, 2004 | 11:09 AM
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If you do a search, you will finds numerous links about this. For one, the throttle position sensor could be bad or out of adjustment. Take your throttle body off and clean it with throttle body cleare and replace the gasket as well. There are just so many things that can screw up an idle. My fuel pressure regulator caused this for a year before I figured it out. Fuel filter to a certain degree can do it also as can gasket leak around the tb.

Good luck,
 
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Old Oct 22, 2004 | 11:51 AM
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Thank you! I suspected the throtle position sensor, but after paying over $100 for an IAC I was a little gun shy to pay $65 for a TPS.

I will try the suggestions .....thanks
 
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Old Oct 22, 2004 | 02:11 PM
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you can test first before you buy:

https://www.ford-trucks.com/article/..._code_124.html
 
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Old Oct 22, 2004 | 02:17 PM
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Awesome thanks for the link!
 
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Old Nov 4, 2004 | 11:23 PM
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Well, I replaced the AIC, the TPS, cleaned the throtle body....and it still surges!

After disconecting the batery to install the tps, the surge went away for a day or two, but now it is back. I suspect the computer was reset when the batery was disconected????
Also, the idle goes up when I put it in gear and stays high until I step on the brake and come to a complete stop, then it drops down.

This is driving me nuts! Help!
 
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Old Nov 5, 2004 | 02:29 AM
  #9  
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May have a bad ECT. Engine Coolant Temperature sensor. The PCM takes info about engine temp from this sensor for idle control settings. Its mounted in the lower intake manifold just behind the water neck for the thermostat. But it should have triggered a "check engine" light and code in the computer.
 
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Old Nov 5, 2004 | 06:38 AM
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I'm in the same boat with ya Ed!! My Bronco is doing the same thing (and has for the 5 years I've had it!) and I've replace the IAC, TPS, dist cap and rotor, plugs, wires, fuel filter and fuel regulator. Hadn't heard about the ECT though....will try that this weekend. I've read on other forums that this is a problem for alot of Fords'....cars, trucks, 6 and 8 cyl...around the mid-late 80's. A friend's Dad's 89 F150 6cyl does the same as my 87 302!!

My daughter wants to put pixy dust on it!! Might have to try that!!
 
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Old Nov 6, 2004 | 12:30 PM
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I remember my first Bronco had the same problem. This was due to a bad Thermostat. I guess it had to deal with the temp. of the engine.

Now my second Bronco has the problem and the Check Engine light comes on and off. I will look into the AIC later and then go down the list.

Thank you guys!

-Stranger
 
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Old Nov 6, 2004 | 12:48 PM
  #12  
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Sounds like the egr is stuck open. take it off and clean it up and make sure its not getting vacume at idle.
 
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Old Nov 9, 2004 | 07:11 PM
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run the codes and see if any are given!
 
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Old Nov 10, 2004 | 10:05 AM
  #14  
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Originally Posted by Ed_B1
Well, I replaced the AIC, the TPS, cleaned the throtle body....and it still surges!

After disconecting the batery to install the tps, the surge went away for a day or two, but now it is back. I suspect the computer was reset when the batery was disconected????
Also, the idle goes up when I put it in gear and stays high until I step on the brake and come to a complete stop, then it drops down.

This is driving me nuts! Help!
I had the same stuff happening- I ended up replacing the throttle body and all is well
 
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