Bronco 5.8L acceleration issues
Thread Starter
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Junior User
Joined: Jun 2011
Posts: 50
Likes: 0
Bronco 5.8L acceleration issues
Hi Folks!
I'm at the end of my rope trying to diagnose an issue with my truck a 1990 bronco 5.8l with about 135,000 miles. It goes like this...
Start the truck cold and runs like a champ for about 3-5 minutes.
As the temp gauge rises the hesitation starts. As it reaches normal op temp it becomes predictable when it hesitates such as starting from a light or under certain acceleration loads. For example if on the freeway going say 65 it runs fine no hesitation or bucking. If I try to accelerate if falls flat on its face. Ease of the gas and feather it, it keeps me going. Going up a hill immediately causes the hesitation.
I have no codes in the system.
I have replaced the following parts in attempt to fix the problem... And some parts broke along the way while trying to fix the problem.
Egr & sensor
Erg tube
TPS
O2 sensor
Fuel filter
Fuel Pump
Spark plugs
Spark plug Wires
Cap & Rotor
Distributor
Battery & Cables
Alternator
Both catalytic converters
I have no idea what else could cause this issue. Please help guys
I'm at the end of my rope trying to diagnose an issue with my truck a 1990 bronco 5.8l with about 135,000 miles. It goes like this...
Start the truck cold and runs like a champ for about 3-5 minutes.
As the temp gauge rises the hesitation starts. As it reaches normal op temp it becomes predictable when it hesitates such as starting from a light or under certain acceleration loads. For example if on the freeway going say 65 it runs fine no hesitation or bucking. If I try to accelerate if falls flat on its face. Ease of the gas and feather it, it keeps me going. Going up a hill immediately causes the hesitation.
I have no codes in the system.
I have replaced the following parts in attempt to fix the problem... And some parts broke along the way while trying to fix the problem.
Egr & sensor
Erg tube
TPS
O2 sensor
Fuel filter
Fuel Pump
Spark plugs
Spark plug Wires
Cap & Rotor
Distributor
Battery & Cables
Alternator
Both catalytic converters
I have no idea what else could cause this issue. Please help guys
Thread Starter
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Junior User
Joined: Jun 2011
Posts: 50
Likes: 0
Would it run different with it unplugged at temp?
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Thread Starter
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Junior User
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The check light activated. No difference for the better.
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New User
Joined: Jun 2014
Posts: 15
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From: Abbotsford
You could replace the temp sensor, they are cheap and I have seen a lot of problems related to temp sensors. Or find the resistance chart for the sensor and check it when warmed up, don't have the chart handy.
Lead Driver
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
Plug that back in, and try unplugging the air temperature sensor on the intake manifold. It looks similar to the coolant temp sensor. If no change again, try unplugging the MAP sensor.
I know having you do this sounds goofy, but the computer will generally substitute a value that works good enough when you unplug sensors.
I know having you do this sounds goofy, but the computer will generally substitute a value that works good enough when you unplug sensors.
it might have made the problem worse. Maybe its just me. I'm at a complete loss right now.
Hotshot
Joined: Sep 2001
Posts: 11,958
Likes: 228
What does top of the line plugs mean? If they are Bosch platinum 4 or another gimmick plug, switch to standard Motorcraft or Autolite.