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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: 8,054
    It's probably the exhaust contracting on cool down.
  • muddingmudding Posts: 3
  • 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.
  • This isn't the right place to ask these questions. Havn't you guys ever heard of Someone needs to ask mommy if he can go outside once in a while.
  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    Why not make this the place? :)

    kcram - Pickups Host
  • obmobm Posts: 2
    No I've never heard of That's why I asked for help. Didn't need help with my Fords.
    I'm not going to complain about GMC, they gave me 2 torque converters 1 Reman. tranny 1 brand new 2004 tranny with 100K warranty, new front hubs, brake pads and rotors all the way around. Rented me a car that we had for 3 weeks and towed my truck several times for several hundred miles.
    Anyway the cam sensor for the 2001 is different than the generic 2002 and newer uses that the Chevy dealer said was the replacement. Got a 2001 specific sensor from Standard [after market] and all's well for about 3 weeks and 1000 miles.
    P.S. Someones mommy should tell junior to take his nap and put the computer away..
  • I have the same problem with my 2003 4.8 silverado. but it only does it when i reset the computer or mess with the program. it will idle low and and sometimes die when i stop or turn hard. Now here's the kicker after a week or so it will gradually get better until it idles just fine. that is in till the next time i re program something on the computer. And i never get any dtc's. Is there anyone else out there with this problem or maybe a solution?
  • tcush1tcush1 Posts: 1
    I have a 2001 that is having the same problem. Today it won't even turn over. I had just a couple of "no engine turn" in the past year but today it won't react at all. I'm guessing it's either the anti-theft or a relay. It would still turn over if it was the fuel pump, just not start. Did you have any luck?????
  • I have a 2003 Silverado SS with 6.0. Will turn over but getting no spark. Haven't ran computer diagnostic on it yet, but i'm pretty depressed my truck won't start. Maybe I have similiar problem??
  • don't know whats wrong with your truck but i am curious let me kn ow whats up when you get it fixed
  • Not sure if its the problem, check your crank sensor. Had a Jeep and it goes out on it about twice a year. Cost $31.00 for the jeep sensor.
  • When let off of accelerator at any speed but especially above 50mph, there is slack between the engine and rear end/trans and or both. Truck has 140,000 miles, u-joints have been checked.
  • My 2003 GMC Sierra 2500HD with the 6.0 liter has a MAF code according to the service tech working on it. He however has test the MAF sensor and believes it to be working properly. After some additional testing he is now telling me that the code and the rough idle are caused by a leaking intake manifold gasket. Is this possible?
    Please help.
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