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Chevy Silverado and GMC Sierra Gasoline Engine Problems

I have a 99 Silverado w/5.3L engine. The idle speed is too low. It gets as low as 430 rpm when I firsty put the tranny in drive and then the idle increases to a more acceptable level. There are no DTC's. This problem is most noticeable when you pull up to a stop. The engine rpm's get low enough to dim the lights and almoist stall the engine. The engine has 62k miles.


  • chrisarachrisara Posts: 2
    I am have the same exact problem with my 2003 4.3. Did you find a solution to the problem? If so please email me.
  • Ditto fellas, I just bought an 01 silverado 5.3L w/ 66,000 miles, and the idle adjustment is too low. I don't know what it should be,(my tach reads 200-400 w/AC on), but i know it shouldn't almost choke down at every stop (as well as the headlights dimming.)The thing is, its not a rough idle, it runs very smooth but just so low that it almost chokes, and surges when given gas.Some have suggested a vacuum leak, faulty ground, or ECM problems. Still looking for answers. All advice is greatly appreciated. Thanks
  • muddingmudding Posts: 3
    I have a 2003 Sierra 2500 4x4. After the truck sets for about 20 minutes you hear a very loud "pop". The dealership has replaced the heat shield and that didn't fix the "popping". Any ideas???? Please........
  • obyoneobyone Posts: 8,065
    It's probably the exhaust contracting on cool down.
  • muddingmudding Posts: 3
    It's much louder than the normal cooling down noises. It's a loud "pop" or "ping".
  • Hey guys, problem solved!!! A friend recommended I call his mechanic, and he told me the low idle was a common problem on these engines. Actually, the real problem is that the accelerator is sticking (although this is not as evident as the low idle; this is why you feel the surge, instead of a smooth acceleration. The low idle is a by-product of this problem). The problem is due to hydrocarbon (sludge) buildup inside the throttle body, and possibly the air flow sensor. He cleaned both (I assume with something like common carb cleaner?). Anyway, she runs like a charm now! I was amazed at the smooth transition of the tranny!!! This was because the accelerator was sticking & had nothing to do with the tranny. The tach has gone from 300-400 in gear w/ac compressor on (almost choking at stops) to an even 500 & idling perfectly. Just want to emphasize that you may not feel the accelerator sticking, but if you experience low idle, you may be surprised at the difference when you do this! He charged me $40 to do this but said the problem may recur in 25,000 miles & may need cleaning again. However, I believe these cleaning procedures may be covered in a Chilton's or Haynes manual. Hope this helps & good luck guys
  • I have a 2001 chev silverado with the 4.3L v6 it seems that any time the tranny shifts up and the rpm's drop to around 1000 I get a labouring sound from the engine a the whole truck vibrates. If you increase the rpms to say 1200 it goes away. Any ideas? It does it at all speeds but only when the rpms are around 1000
  • I want to replace my 195 degree thermostat with a 180 degree one for my 2006 GMC Sierra with the 4.8 litre engine. Anybody know where to purchase one or know of one from a different model that will fit?
  • Having problems with my 2001 silverado 2wd. it rotates over and idles until it shuts off. I just changed spark plugs and they smelled like fuel. It ran for a bit longer with the new spark plugs but then died down.I was thinking about changing the fuel filter and cleaning the throttle body for build up. i was thinking of fuel system because it had been sitting the last 7-8 months because i just got out the military.
  • I have a 2002 silverado 2500hd auto,6.0 engine 100,000 miles, there is a intermitten miss or skip in the engine under load 30-65 mph, no codes on scan, o2 sensors replaced,fuel tank cleaned & fuelpump replaced, fuel filter replaced, plugs & wires replaced, engine serviced, trans serviced , computer reprogramed by dealer, still got the miss sometimes its not so noticeable sometimes its more of a jurking, please someone help I love this truck
  • 1999 Silverado 2500 6.0 L motor. In the morning or after sitting for a short while the oil pressure does not rise to a sufficient pressure to prevent the lifters from rattling until the pressure gets to approx. 20psi. Any thought

  • What brand of fuel have you used during it's life. Have you had the injectors cleaned recently. It my be concidered a soft miss from one or more partially restricted injectors.
    It's my understanding the computor is not scheduled to record and error until it misses more them 250 times.
    I had spark plug wires go bad and the computor didn't record a fault. I finally had to have the service technition go for a test ride with the computor attached and have him watch it very carefully to even see the miss.
    Best of luck
  • Since I bought the truck used in '03 it often will not turn over and crank. Sometimes it starts as soon as I turn the key, but often I have to pat the accelerator and hold the key. I have checked the fuel pump, and it checks out. Someone told me that it might be the fuel pressure regulator, and others have said to replace the fuel filter. I have no problems once the truck is cranked and running, but as soon as I turn it off and try to start it again it may not crank. Please help
  • obmobm Posts: 2
    I have a 2001 3500 with an 8.1L engine with the check engine light on. It scans code 342 for cam position sensor low voltage. Replaced the cam position sensor with a new GM unit. Cleared the code. The light comes back on after about 30 miles driving. Same code.

    Is there more than one cam position sensor on this engine or does anyone have any suggestions on why I'm getting the low voltage reading? The engine runs great. Do you think it will leave me by the side of the road?

    Thanks for any advise anyone can give me.
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