1996 Chevrolet Silverado 96 Chevy z71. Surging, loosing power

Tiny
ARKANSASROUGHNECK
  • MEMBER
  • 1996 CHEVROLET SILVERADO
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 215,000 MILES
I can crank my truck get in and go sometimes it has a hard crank sometimes it doesn't. After it warms up it starts surging and loosing power and kinda sounds like its being deprived. Ive changed plugs and wires, one side of the plugs was fine but the other side plugs were black. Ive changed the distributor, Map Sensor, and had the timing reset at a shop. I cranked it just a little while ago and it made kind of a knocking noise so I shut the truck of. What could be wrong?
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Friday, November 29th, 2013 AT 1:17 PM

10 Replies

Tiny
HMAC300
  • EXPERT
What kind of knocking noise deep or on top of motor? try this for surging
http://www.2carpros.com/articles/throttle-actuator-service then scan for codes and check fuel pressure
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Friday, November 29th, 2013 AT 4:10 PM
Tiny
ARKANSASROUGHNECK
  • MEMBER
The knocking seems to be coming from the top of the motor it only does it till it warms up and after it warms up is when it starts the surging and loosing power. Some of my friends told me my motor may be going bad but im not sure.
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Friday, November 29th, 2013 AT 7:06 PM
Tiny
HMAC300
  • EXPERT
If it knocks when you start and quits when you get warm it may be piston slap you can drive practically like that forever, it's annoying but thtat is about all. I'm assuming it's a 350 try the link I sent to stop the surging as it may be the throttle plate dirty an dcheck fuelpressure. Have a mechanic check the knock i'm sure he will agree with me.
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Saturday, November 30th, 2013 AT 5:46 AM
Tiny
ARKANSASROUGHNECK
  • MEMBER
I did everything in the link you sent me this morning. Went and drove it about 10miles or so and it did fine and then it started surging and cutting out again. It acts up for a lttle while then it evens out and runs fine for a few mins then it starts doin it again. I have been to every mechanic in my town since it started messing up and they all told me it was diffrent problem I tryed everthing they have suggested and have still not figured out the problem.
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Saturday, November 30th, 2013 AT 5:15 PM
Tiny
ARKANSASROUGHNECK
  • MEMBER
And yes you are correct the motor in my truck is a 5.7L Vortec 350
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Saturday, November 30th, 2013 AT 5:17 PM
Tiny
HMAC300
  • EXPERT
Did you scan for codes and check fuelpressure as well? 60-66psi for fuel auto parts rent gauge. Also check for a vacuum leak with choke cleaner.
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Sunday, December 1st, 2013 AT 5:50 AM
Tiny
ARKANSASROUGHNECK
  • MEMBER
I checked the fuel pressure and it was fine. Scaned for codes and it keeps popping up a random misfire. It popped the code up before and thats when I changed plugs and wires and had the timing set. The code went away for a few days then popped back up and has been like that since
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Sunday, December 1st, 2013 AT 1:53 PM
Tiny
HMAC300
  • EXPERT
Have a pro check this as misfires can be a multitude o f things. They are not easy to find unless it's a compression issue.
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Sunday, December 1st, 2013 AT 3:44 PM
Tiny
ARKANSASROUGHNECK
  • MEMBER
I took it to a pro when the mifire code popped up and he said the timing was off so he timed it. Like I said I drove it for a few days after with no problem then it came back. Ive been to every mechanic in my town and have done everything they said. I went to a mechanic in the next town over from me and he said it was not misfiring and that it seemed like nothing was wrong to him. Yet the misfire code is still up and its still surging! Im lost I dont know what to do. Im about to the point of dropping another motor in or just parkin it in the backyard and let it sit.
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Sunday, December 1st, 2013 AT 4:40 PM
Tiny
HMAC300
  • EXPERT
Misfires have n't much to do with timing but I've h ad to replace the dist in mine as I've got a v6 but take the cap off andsee if you can move the rotor either direction. If it does pull it out and see if the gear is all torn up if it is get another distributor. Then it will have to be timed again because you'll get a p0016 code probably
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Monday, December 2nd, 2013 AT 6:36 AM

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