Mechanics

ENGINE MISFIRE CRUISING ON THE HIGHWAY

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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Michaelcox1
October 5, 2012.




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

Saturntech9
Oct 5, 2012.
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.

Tiny
Michaelcox1
Oct 5, 2012.
Can anyone help please only vehicle I have to get to work and pick up the kids from school

Tiny
Michaelcox1
Oct 5, 2012.
When is the baro sensor reading 4.25 volts at idle or with the key on engine off?
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Saturntech9
Oct 5, 2012.
At idle or on the throttle

Tiny
Michaelcox1
Oct 5, 2012.
Do you have any codes in the computer?

Saturntech9
Oct 5, 2012.
No not at all. Im lost.

Tiny
Michaelcox1
Oct 5, 2012.
So it never changes from 4.25 volts?

Saturntech9
Oct 5, 2012.
No not at all. So it's at max all the time thinking it needs max fuel.

Tiny
Michaelcox1
Oct 5, 2012.
What size engine do you have?

Saturntech9
Oct 5, 2012.

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