1996 Ford Bronco idle and hesitation

Tiny
JILLA
  • MEMBER
  • 1996 FORD BRONCO
  • 5.8L
  • V8
  • 4WD
  • AUTOMATIC
  • 146,324 MILES
Hesitation at startup and acceleration at around 30-40mph. Ive recently changed spark plugs, wires, ignition coil, distributor cap and rotor. Problem got a little better but still having hesitation on acceleration. Also I done od2 test the check engine light only codes read is o2 sensor bank 1 and 2 to rich. Please help I need truck for work.
Sunday, November 30th, 2014 AT 1:19 PM

27 Replies

Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Okay, when you accelerate does it have a pause then go when you press the pedal, or is it more of that it doesnt seem to have good power? I would suggest checking your TPS sensor. Remove throttle body and clean both sides (you will need a new gasket). Check to make sure your coolant level is good through the whole system with no air in the system at all. Check air filter, check engine timing.
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Sunday, November 30th, 2014 AT 2:29 PM
Tiny
JILLA
  • MEMBER
  • 46 POSTS
It idles fine in park. While driving When I press the accelerator it stumbles a little bit but then it picks up seeming like power issues, when it gets to about 30-40mph the whole truck shakes, When I let off the gas the shaking stops.
I have brand new air filter also
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Sunday, November 30th, 2014 AT 2:56 PM
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
I would recommend taking to a pro and have him look at your live data and diagnose what he sees to be the issue. My first guess is the TPS sensor. Do you have a meter to read voltage?
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Sunday, November 30th, 2014 AT 3:02 PM
Tiny
JILLA
  • MEMBER
  • 46 POSTS
Yes I have a volt meter
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Sunday, November 30th, 2014 AT 3:05 PM
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Ok, with the key on go to your TPS sensor on the throttle body. It should be three wires if I remember right (possibly orange, green, and black?). One wire should be a constant 5 volts, another should be ground, and the other should be your signal voltage. While it is plugged in find the signal wire. It should read about.60 volts at closed throttle and slowly open the throttle by hand while watching the voltage climb. It should go up to about 4.5 volts. If at any time you see point where the voltage drops off while you turn the throttle up. Then that should tell you that you have a dead spot in the sensor.
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Sunday, November 30th, 2014 AT 3:11 PM
Tiny
JILLA
  • MEMBER
  • 46 POSTS
Ok I'll try that and get back to you
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Sunday, November 30th, 2014 AT 3:13 PM
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Ok, Does this truck have a mass air flow sensor? You try to spray some mass air flow cleaner on the MAF to clean it off to see if that helps as well.
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Sunday, November 30th, 2014 AT 3:16 PM
Tiny
JILLA
  • MEMBER
  • 46 POSTS
Yes I have maf sensor and no I have tried that yet either
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Sunday, November 30th, 2014 AT 3:18 PM
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Ok, these older fords in these years can be a bear at times to diagnose. A lot of the components can cause similar issues. You could also rule that the EGR, and DPFE (differential pressure feedback egr sensor) could be a culprit. This is why I recommend taking to a pro to chase it all around. Do you have and OBD1 reader for this truck? I know that oreily auto parts carries the Ford OBD1 reader for like $32.
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Sunday, November 30th, 2014 AT 3:23 PM
Tiny
JILLA
  • MEMBER
  • 46 POSTS
The 96 Bronco uses the odb2. I used that at O'Reilly and the only codes it throw were the o2 sensors. I ran out of day light and its freezing here in Minneapolis, mn so couldn't get to the volt testing and cleaning the maf sensor.
One thing I noticed when I put the truck in gear I can hear on the passenger side sounds like the spark plugs are puting, after about 3 putts it stops and runs but not exactly how it should.
I didn't have any of these problems until I changed the oil. And that led me too do the basic tune up wires, plugs everything I posted I've done.
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Sunday, November 30th, 2014 AT 9:11 PM
Tiny
JILLA
  • MEMBER
  • 46 POSTS
And yes it sometimes do have a pause and then go when trying to accelerate
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Sunday, November 30th, 2014 AT 9:13 PM
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Sorry I havent got back to you sooner. Sometimes my email alerts go to my spam folder. What you need to check or have looked at is the fuel pressure, a clogged converter, fuel filter, TPS, EGR valve, MAF sensor.
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Tuesday, December 2nd, 2014 AT 7:51 AM
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Rent a fuel pressure gauge from a parts store. Fuel pressure with key on engine off is 30-45 and should hold steady. OH and also check the vacuum line at the fuel pressure regulator. If you remove the hose and see raw fuel coming out of the regulator then you need to replace the it (busted diaphram). That would also explain your rich codes you got from the o2 sensors.
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Tuesday, December 2nd, 2014 AT 8:00 AM
Tiny
JILLA
  • MEMBER
  • 46 POSTS
Ive changed the dpfe sensor now its at normal idle but when in gear it still hesitates and shakes really bad at 25-30mph. And there's no check engine light on anymore.
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Tuesday, December 2nd, 2014 AT 9:26 AM
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Ok, you need to check what I just wrote before regarding fuel pressure and the fuel pressure regulator. Rent a gauge from parts store if you do not own one.
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Tuesday, December 2nd, 2014 AT 9:34 AM
Tiny
JILLA
  • MEMBER
  • 46 POSTS
Ok will do and ill get back to you asap
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Tuesday, December 2nd, 2014 AT 9:44 AM
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Sounds good. We just need to be able to start eliminating what the issue could be by testing.
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Tuesday, December 2nd, 2014 AT 9:45 AM
Tiny
JILLA
  • MEMBER
  • 46 POSTS
When I get off work ill go and get the feul pressure test kit and let you know from there.
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Tuesday, December 2nd, 2014 AT 10:09 AM
Tiny
JILLA
  • MEMBER
  • 46 POSTS
Well I just replaced the pressure regulator and now it's running even worse then befor
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Tuesday, December 2nd, 2014 AT 4:30 PM
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Umm.I didnt want you to replace it. I wanted you to do the tests and see what you are getting so we know which way to go.
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Wednesday, December 3rd, 2014 AT 1:55 PM

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