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Chevy Silverado and GMC Sierra Gasoline Engine Problems



  • wmazwmaz Posts: 3
    I would suggest you find a repair shop that has a good scanning tool, like a snapon. They will be able to tell you which cylinders are misfiring. The code should tell you but a P0300 is random misfire. I had a similar problem and had to replace the PCM. Turned out the connections for the fuel injectors were firing at the wrong time. The terminals were right next to one another. If your Check Engine light is flashing you are doing damage to your converters. Don't drive any more than you have to.
  • Thanks wmaz, The Check Engine light hasn't came on in a long time. Normally it will vibrate and then the light will come on without flashing. I'm looking into getting a new PCU from a salvage yard. Crossing my fingers it helps. Thanks again.
  • hi all...guess ill start from3 days ago..3 days ago, while driving to work, truck spitted and sputtered then quit. revved it for about 15 min..all was fine..after driving 6 more minutes down the road does the same thing, but does not crank back up..i have it pulled to my home.put the diagnostic on it and got codes po171 & po174..replaced the bank 2 /sensor 2 o2 sensor and fuel filter. cranks right up and runs. now idling rough and wanting to stall out.check..ran diagnostic again over 10 times over last 2 days and getting 0 codes, but still really cannot drive it until the rough idiling and the wanting to stall issue is fixed....any thoughts or suggestions?
  • diagnostic test shows misfire on 2,4,& 6 changed plugs wires, rotor ,and cap running worse than when i brought it in it idles rough boggs down revs between 2&3 and barely moves removed three of the plugs that i just replaced and they were black pistons sound off like they r goin to shoot through the block mechanic spent eight hours on it and has been stumped he smelled the exhaust and says it smells like its dumping fouled gas what ever that means did it by bad gas did somebody dump something in my tank or is there a different solution
  • i have a 2000 chevy tahoe and a had the same problem just go to any auto parts and buy a throtle body cleaner remove your intake hose and spray it real good in your throtle body, and it will take care of the problem.
  • lfeleslfeles Posts: 2
    Mine started when I changed to synthetic oil. Was my first oil change. They should extend our warranties on this engine.
  • just_truckin13just_truckin13 Posts: 3
    edited October 2010
    2006 GMC Sierra 1500 SLE 5.3L V8 Vortec - 1st owner
    -I feel a rough idle while in park or stopped during travel. new plugs and wires, new air filter, cleaned throttle body and added fuel injector cleaner.

    -I'm unable to locate a PCV or EGR valve. I've been told that my particular vehicle does not have a PCV valve.

    -Suggestion? Advice?
  • obyoneobyone Posts: 8,065
    Clean or replace your idle air controller.
  • Unfortunately my sierra is a later model which does not have a IAC. Thank you for the reply
  • hi i have a 2000 silverado 4.3 just replaced intake manifold gaskets,and now its not firing on number 5,got new plugs and leads swaped number 3 injector to number 5 pulled plug lead off 3 and engine noise changed pulled lead off 5 no change,had compression test on 3 and 5 both same reading ,got good spark ,never replaced intake gaskets went ok but the last bolt snaped so had to take it off again and replace bolt now have this missfiring any help would be nice its hard to find as im in uk thank you
  • I've got a '99 silverado 1500, and it runs very irradic. under very slow acceleration it's fine but if i get on it at all it stumbles and falls on its face. Also when cruising down the road it runs fine until I start going up hill, then it starts to stumble again until i hit the gas and kick it into another gear. This truck also wants to die when i shift from R to D. This is very aggravating... :mad: It seems like the cooler the temperature gets the better this thing runs.. any help would be greatly appreciated
  • dwh4dwh4 Posts: 1
    Have 99 GMC Sierra with same problem last two winters. Changed fuel pump, filter, regulator, and MAF. Still get service engine light when cold, driven short distance, stopped and then restarted in short amount of time (less than one hour). Was thinking of changing EGR but you said that did not work. did you find fix yet?
  • I know these trucks have a problem with their "Heat Temp Sensor", it tells the computer to keep dumping fuel because the computer thinks the motor is still cold, it keep's flooding the engine! Just something to check !
  • Check your "Heat Raiser", sometimes these things will rust closed and cause this noise! The Heat Raiser is located on the exhaust manifold ! Just turn it by hand with engine cold, so you wil not get burned! If it turns or works , then not the problem and you will have to look else where !
  • truck lifters tap when first cranks up in mornin when engine warms it smoothes out until park after about a hour it does the same until engine warms then smoothes out again
  • etatetat Posts: 4
    does this problem have any todo with the catalic comverter or sensors its hard to see the atcual problem because when that happens i just turn off the truck and restart it and the error message dissappears,so i can't even put the diagnastics machine because when that happens i have to restart,do anyone have the same problem?if so what did you do about it what is the problem
  • etatetat Posts: 4
    not yet when that happens iam forced to turn off the truck and restartit so i can;t even take it to a mechanic where he can hookmit up to a dia,machine so,iam left with no answers to where to begin looking for my problem
  • etatetat Posts: 4
    my truck don;t low idle it runs great then all of sudden it slows down and the light appears that says reduce engine power then i have to turn truck off then turn it on again then the light dissappears
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