1993 Ford Bronco hesitates and sputters at highway speeds

Tiny
MCCULLEK
  • MEMBER
  • 1993 FORD BRONCO
  • V8
  • 4WD
  • AUTOMATIC
  • 125,000 MILES
This is a well maintained Bronco and I recently had the transmission rebuilt, and the motor tuned up. We replaced all of the spark plug wires and plugs, etc. I also had the radiator flushed out and installed a new thermostat.

The engine cranks and runs great, even when it has been sitting for a month or longer. Around town, it runs great, although the temperature sensor seems to run hotter than normal, the engine never over heats. I took it to a radiator shop and they said to put an original thermostat part in it and I did that, but it still seems to run at a higher temperature and occasionally moves over to the over heat area, and it does seem to be running hotter, but the engine doesn't really over heat? Around town it runs great with lots of take off power and it cranks and idles well.

However, when you take it out on the highway, once you get up to around 50-55 miles an hour, it starts sputtering and hesitating. If you accellerate, it will kick out of over drive and take off with lots of power, but as soon as it goes back in OD, it starts sputtering and hesitating again.

I'm not sure if the temperature issue is related to the highway hesitation and sputtering, but I would like to solve both issues even if not.
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Saturday, May 17th, 2008 AT 11:49 AM

5 Replies

Tiny
MASTERTECHTIM
  • MEMBER
Unplug the egr valve and see if the problem goes away, if not I think your going to find a bad spark plug and or plug wire.
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Saturday, May 17th, 2008 AT 1:41 PM
Tiny
MCCULLEK
  • MEMBER
OK, I unplugged the electrical connector that goes into the EGR, I assume that is what you are referring to when you say unplug it? This did help considerably, but it did not cure the problem in full. I still get some hesitation when you start up an incline or steeper hill while at higher speeds. The check engine light is on as well, but I'm sure that is to be expected with the EGR being unplugged.

Will it hurt anything to run the engine with the EGR disconnected, or do I need to replace it and plug it back up? I prefer to just leave it off if it doesn't damage the motor in any way.

One other item, I read somewhere that there is a problem with Ford 5.0 V8 motors in my year range in which the 8th cylinder doesn't fire correctly due to the PCV valve being in the rear of the motor and that it needs to be moved to cure this problem. Could this have anything to do with my issue?

Thanks for your help so far.
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Saturday, May 17th, 2008 AT 9:48 PM
Tiny
MASTERTECHTIM
  • MEMBER
I have never heard of the moving of the pcv valve but you can leave the egr disconnected. Also unplug the vacuum line to it and plug it, this should make a real big difference
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Sunday, May 18th, 2008 AT 10:35 AM
Tiny
MCCULLEK
  • MEMBER
Is there a trick to fooling the check engine light so that it works but ingores the ERG issue?
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Monday, May 19th, 2008 AT 7:27 PM
Tiny
MASTERTECHTIM
  • MEMBER
Not that im aware of.
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Tuesday, May 20th, 2008 AT 11:10 AM

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