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Shaking truck and funny acceleration... ahhhhhhh

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ChevyCaGal, Jun 6, 2002.

  1. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    Hey gang... I got a problem... I drove my truck today to work. It ran fine enough until mid morning.... then when it was warmed up and fine it started doing this.... I got to a light and as I was slowing down it began to vibrate and shake. Not really violently, but enough to make me think something is for sure up... at idle it didn't shake quite as bad but idled like garbage. When I hit the gas when it turned green it accelerated really slowly and shook pretty good up until about 8mph.... it would drive and accel slowly up until about 35-40mph... after that it drove fine, shifted perfect and was going on the freeway fine. It would run fine until I slowed down under 10mph then it gets the shakes again. Again repeat the struggle to accelerate if I need to speed up.... another thing to note, my exhaust is not exactly quiet, but it's louder now for sure and it has like it's got some weird go kart thing going on when I gas it. At idle it doesn't do that but it's still way louder then normal. Also on acceleration sometimes it would for a split second right when the gas was hit make a sound like a diesel semi truck (like when they idle) up in the engine... I am stumped where to start to be honest... any ideas to check for because this is new to me. Thanks!
     
  2. MudFrog

    MudFrog 1/2 ton status

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    Might not be your issue, but once when my rear ujoint went bad it did what you describe except for the exhaust and diesel sound. Slowing down it would vibrate extremely bad, and starting off it would vibrate bad and my top speed was about 15 mph. The problem was one of the caps was completely off and one was still in, but the drive shaft never actually dropped..
    So maybe you actually have 2 differen't issues??
     
  3. 74k5inVA

    74k5inVA 1/2 ton status

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    ok, my 94 s10 would do the same thing. it would rumble and shake when i slowed down and idled, sometimes it would not, it also made diesel sounds and had funny exhaust sounds to. the major problem was that the exhaust had to be replaced. i had holes in the pipes (not just the tail pipe, but the one between the cat and muffler and the one from manifold to cat. this results in a different pressure drop that can cause thing to backfire or even shake and idle like garbage. mine did not backfire, but did everything yours sounds like it is doing. once i replaced the exhaust i had less of a problem. another cause of the dieseling was that i had carbon build up. since most of my drives were short (under 5 miles) my engine would never heat up. if i would take a long drive and the engine would heat up and burn most of that build up off then it would not make those noises for a while. also i used injector cleaner, which helped my performance but probably didn't help this problem. i know that the s10 sounds and feels much better after she gets out and stretches her legs. it has more miles on it than my blazer and it is 20 years younger. hope this helps
     
  4. muddin4fun

    muddin4fun 3/4 ton status

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    weird /forums/images/icons/shocked.gif

    I wonder if you blew an exhaust manifold gasket?

    Can you disconnect the exhaust system from the Y-pipe and start it up and test it like that. It would eliminate your cat as the problems.

    I'm lost!
     
  5. 74k5inVA

    74k5inVA 1/2 ton status

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    i would think that if that was the case you could smell major fumes.
     
  6. muddin4fun

    muddin4fun 3/4 ton status

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    Probably...but I've blown header gaskets without smelling anything.
     
  7. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    The rough idle and shaky at low RPM/MPH could be an EGR valve that is stuck or plugged. As for the exhaust sound that could be an exhaust doughnut going or any number or things.
     
  8. 74k5inVA

    74k5inVA 1/2 ton status

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    darn, i forgot to mention the EGR!
     
  9. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    I think it's an exhaust issue the more I look at it... the u-joints are fine and it's vibes at a stand still and the shaft isn't spinning while at a stand still to affect me like that.... the muffler is making odd noises so I can only assume something is plugged. I'm going take it to be looked at because if my headers are screwed up I want a mechanic to say so that way I can use my warrenty I have left on them with Edelbrock. Thanks!
     
  10. 70~K5

    70~K5 1/2 ton status

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    Check the EGR valve the line going to it came lose on the Wifes new '01 trooper going to Reno last month made funny sounds when on the pipe.
     
  11. MNorby

    MNorby 3/4 ton status Premium Member GMOTM Winner

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    maybe a bad sprak plug or wire or just disconnected and it is missing and only noticeable at the slow and stop?????
     
  12. Pugsley

    Pugsley 1/2 ton status

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    I'd say check for crossfiring/shorted plug wires - I had a plug wire on mine that was shorting to the loom, and it had the shakes in a big way.
     
  13. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    EGR...Check it. may have stuck open. EGR doesn't come on till your running about 1500-2k. If it were on at idle it will run like garbage. It will do the same acclerating till it get's into the range it shoudl be operating. Bad plug wires fouled plug can give simular problems. Stuck choke also but it will run real rich at idle will be the tell tale sign of that. You also have that horrible mix control solonoid carb I bet and when that solonoide dies it can give you a simular problem.
    How long since you filled up the truck? might have got a bad tank of gas and plugged the fuel filter. That usualy does the other way arounf. run fine at idel. will accelerated ok then fall on it's face.
     
  14. muddin4fun

    muddin4fun 3/4 ton status

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    the egr might also be the reason you're hearing something in the engine compartment.


    <blockquote><font class="small">In reply to:</font><hr>

    the muffler is making odd noises so

    <hr></blockquote>

    You need new muffler bearings /forums/images/icons/laugh.gif

    If your egr is bad, I'm sure your exhaust can make all sorts of weird noises /forums/images/icons/smile.gif
     
  15. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    I have newer plug wires and plugs... I checked them twice and they aren't messed up... it was running fine for 2 days so I think if I messed them up I would have noticed before then. I just filled up yesterday and dumped in some cleaner crud.... runs just as crappy..... I am gonna tweek the EGR on Saturday cuz it's been too hot to work on it after work in the 100 degree heat. I noticed today the worst it shakes is when I am slowing down to like 5mph when braking and then when I back up... then when I accelerate until I hit just over 10mph it looks like I have crack in the gas tank the way it shakes.... once I hit 40mph (which is hard it's struggling) it's fine.... just can hear the exhaust and now there's a cool tick in the engine.... I just don't know where the issue is. My headers are fine and no holes in the pipes. Like I said I will check the EGR.... thanks guys! /forums/images/icons/smile.gif
     
  16. thatK30guy

    thatK30guy 1 ton status Premium Member

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    What you are experiencing is exactly what my '85 K30 sounds like it's doing, too! /forums/images/icons/frown.gif

    I was given ideas that the intake manifold could have a vacuum leak somewhere. /forums/images/icons/tongue.gif
     
  17. YtseJam

    YtseJam 1/2 ton status

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    It sounds to me like a cylinder misfire. Check for a bad spark plug or wire. Check the distributor cap &amp; rotor.
     
  18. thatK30guy

    thatK30guy 1 ton status Premium Member

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    All those have been replaced for new and there is no difference on the change. /forums/images/icons/frown.gif
     
  19. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    It's not the farging intake itself I found that out... The EGR might be it and I think it is (I checked everything else and there's nothing left)... I am gonna play with that today and if I can't fix it then it goes to a mechanic if not. I have some warrenties left and if I get them in writing that stuff is defective or messed up I can get new if it's the stuff I recently bought....
     

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