ENGINE MISFIRE CRUISING ON THE HIGHWAY

  • Tiny
  • michaelcox1
  • 2000 Chevrolet Silverado
  • 19,300 miles

Why does my engine misfire when I'm cruising on the highway. This usually occurs when I'm climbing a gradual hill. If I give it gas the vehicle jumps

i have replaced all sensors! Fuel pressure is 50 psi where it is suppose to be lost!

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Friday, October 5th, 2012 AT 12:40 AM

19 Replies

  • Tiny
  • saturntech9
  • Expert
  • 29,311 posts

Have you looked at the plugs and wires?Is I worse with the ac on?

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Friday, October 5th, 2012 AT 12:51 AM
  • Tiny
  • michaelcox1
  • Member

Hi thank you! I replace the fuel pressure sender, map sensor, all four O2 sensors, fuel pressure reading is 50psi, spark plugs changed 3000 miles ago, I put a computer on it and it said my barometric pressure voltage is 4.25 which I think its suppose to be reading.5 volts. So i'm very lost can you help me? Oh yeah it idles with a little miss and when I first get on the fuel slowly it bucks and chokes misses bad. Then when I kick it down to the next gear it runs fine. But when its in overdrive going up a hill it does the same thing until it kicks into the lower gear. Any help would be appreciated.

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Friday, October 5th, 2012 AT 12:57 AM
  • Tiny
  • michaelcox1
  • Member

Can anyone help please only vehicle I have to get to work and pick up the kids from school

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Friday, October 5th, 2012 AT 1:24 AM
  • Tiny
  • saturntech9
  • Expert
  • 29,311 posts

When is the baro sensor reading 4.25 volts at idle or with the key on engine off?

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Friday, October 5th, 2012 AT 3:10 AM
  • Tiny
  • michaelcox1
  • Member

At idle or on the throttle

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Friday, October 5th, 2012 AT 11:19 AM
  • Tiny
  • saturntech9
  • Expert
  • 29,311 posts

Do you have any codes in the computer?

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Friday, October 5th, 2012 AT 1:51 PM
  • Tiny
  • michaelcox1
  • Member

No not at all. Im lost.

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Friday, October 5th, 2012 AT 3:51 PM
  • Tiny
  • saturntech9
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So it never changes from 4.25 volts?

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Friday, October 5th, 2012 AT 4:34 PM
  • Tiny
  • michaelcox1
  • Member

No not at all. So it's at max all the time thinking it needs max fuel.

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Friday, October 5th, 2012 AT 5:21 PM
  • Tiny
  • saturntech9
  • Expert
  • 29,311 posts

What size engine do you have?

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Friday, October 5th, 2012 AT 5:45 PM

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