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Chevy Silverado and GMC Sierra Gasoline Engine Problems



  • 1998lincoln1998lincoln Member Posts: 108
    You never told me what type of automobile you have ! One thing to look at , the
    heat sensor is telling the motor it's still cold and needs to inject more fuel !
    This happens with silverado's sometimes ! Just something to look at ! Good Luck !
  • ms1378ms1378 Member Posts: 7
    Thanks for replying, will take a look at that..bythe way I own a 2001 2500 6.0 vortec..gas sucking beast that it is, got it when gas was not so much of concern, but it still pulls any trailer that i hook to it w/ out problems.
  • obyoneobyone Member Posts: 7,841
    I'd be more concerned if the oil pressure didn't move in relation to rpms. What you describe as occurring would be the correct operation of the gauge.
  • eliaselias Member Posts: 2,209
    rj, yes it should still run if you unplug the O2 sensor after the cat.
    it seems likely that your truck's catalytic converter is clogged.
  • redi_jediredi_jedi Member Posts: 9
    I had to change the lower intake gasket a couple days ago, had a bad leak all of a sudden. This was by far the dirtiest motor I have ever been into. There was at least 3/8 to 1/2 inch of sludge on the hold down plate for the lifters and a 1/4" at least of build up with sludge on top on the floor of the valley. It only has 87k on it! I have a 73' impala with 84k on it and that looked like new compared to this. Well, I got it all back together and so far it has not died yet. I'm not going to hold my breath though cause last time I thought it stopped dying I was wrong. I'm keeping my fingers crossed. If it dies again I'll unhook that O2 sensor and see what happens. Thanks for the input.
  • redi_jediredi_jedi Member Posts: 9
    well, no go, brother drive it to work and almost didn't get back home. Died half dozen times or so, along with popping and banging and backfiring. Would be happy to roll it off a cliff !!!
  • obyoneobyone Member Posts: 7,841
    Yep sludge is never good.
  • pickupman94pickupman94 Member Posts: 2
    i think its time to replace the comp that will cause all the problems that you have mentioned and especially if u have replaced all the items you've listed
  • pickupman94pickupman94 Member Posts: 2
    i have a 94 silveraldo that i just replaced the plugs and wires in and done them 1 by 1 now the truck is running worse than it did b4 i replaced them it spits and sputters like i got a plug wire off but there isnt and has a big loss in power but it dont cut off does any1 have any ideas and also done a tranny service the motor has a skip in it and i have a few ideas but just wanted to see if anyone has had a similar problem
  • 1998lincoln1998lincoln Member Posts: 108
    edited April 2010
    When Stalling , here are some things to look for ! Good Luck

    To test the exhaust, remove a spark plug, hook up a compression tester, crank over engine, when it starts, if the compression is high, cat. converter is stopped up and has to be replaced !
    the engine temperature sensor! It was failing so it was telling the throttle positioning sensor that the motor was cold so it kept dumping allot if fuel. So when the gas was pushed it flooded it and it would die!
    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. clean both (I assume with something like common carb cleaner?).
  • forkliftjoeforkliftjoe Member Posts: 1
    1999 GMC Silverado 5.7L 67,000 miles. HIGH OIL PRESSURE
    The engine oil pressure is too high, on start up the pressure gauge pegs past 80 PSI. The oil filter o-ring blew out. I changed the oil and filter 10W30 and it blew
    the o-ring out again so I tightened the heck out of it and am able to start in now.
    The oil pressure is still maxed on the gauge, after warm up at idle it will drop to about 50PSI but if engine RPM is increased it goes past 80PSI.
    Any sugestions on what might cause this? Is it possible that the relief valve is stuck? Where is the relief in the pump? Does the oil pan need to come off?
    Can it be removed without pulling the engine? Thanks for any help!
  • wolvestxwolvestx Member Posts: 1
    I am looking at purchasing a 2001 Chevy 2500HD Crew Cab 6.0 2WD. Before doing so I am trying to find to the average fuel economy. I currently own a 2005 Toyota Tundra SR5 Crew Max with a 4.7. The gas mileage is horrible at 14 Cty/Hwy combined. Any help would be appreciated.
  • obyoneobyone Member Posts: 7,841
    You won't find EPA mileage numbers due to it being a 2500 series truck. However, if my memory serves me correctly I think you'll average 10 mpg loaded and 12 mpg unloaded.
  • redi_jediredi_jedi Member Posts: 9
    I got it all straightened out, ended up being the fuel pressure regulator. Sure threw me off the way it was acting, wish it would have done the hickupping $400 sooner. I would have started with the regulator instead. But hey, on the plus side, it has alot of new parts that i shouldn't have to worry about for quite some time. thanks for all help
  • ms1378ms1378 Member Posts: 7
    I have a 2001 2500 crew 4x4 , trailer or no trailer, loaded or empty I get 10 mph..maybe 11 with the wind at my back
  • speedorepair1speedorepair1 Member Posts: 1
    did you replace the sensors or fix the wiring or both? i have the same problem on my 04 silverado with the 5.3 engine.
  • solocamsolocam Member Posts: 3
  • solocamsolocam Member Posts: 3
    My truck sounds like a Diesel when I start it up. It seems to take longer for it to go away. Any ideas? I only have 56,000 miles on it. I have tried the oil filter with check valve, Lucas oil stabalizer. I am scared it is getting worse. Please Help......
  • ihategmanymoreihategmanymore Member Posts: 6
  • hvychev77hvychev77 Member Posts: 3
    hard to find until you get a "check engine" light on....Did u try the crankshaft sensor or the coil packs?
  • redi_jediredi_jedi Member Posts: 9
    kinda sounds like the oil pump is starting up dry, or or maybe weak. if the oil pump don't get the oil flowing right away, it can produce the sounds you are hearing. i would think the miles are low enough that it shouldn't be a problem with bearings, but worn out crankshaft bearings will make that sound too. does it go away once it is warmed up? i would check the oil pressure before i do anything. maybe even check the oil filter, if it is clogged up it would prevent the oil pump from getting the necessary flow, which would result in the diesel noise on start up. once the oil gets hot and can flow easier, it might lessen the noise. Just a few thoughts. Good luck
  • redi_jediredi_jedi Member Posts: 9
    try the fuel pressure regulator
  • dtsddtsd Member Posts: 1
    My 1994 GMC Sierra 1500 4x4 has all of a sudden decided to not idle without dying. My son was pulling out from a driveway and it started to idle and try to die. He has changed fuel filter twice in 3 days, plugs, wires, fuel pump, O2 sensor. Nothing has seemed to help. It will almost always die when idling, no matter how long the engine has been running, and sometimes dies when slowing down to turn a corner. Any more ideas except a mechanic. Thanks in advance.
  • obyoneobyone Member Posts: 7,841
    Idle air controller.
  • redi_jediredi_jedi Member Posts: 9
    does it die at random? then start back up? I have a 99' chevy k1500 and that's what it did. ran fine but died at any given time at any temp., I spent $400 on various parts. plugs, wires, coil, dist. cap, rotor, O2 sensor, map sensor, crank sensor, fuel pump relay, fuel filter. then one day it hiccupped real hard a few times. so i changed the fuel pressure regulator and so far so good, seemed to have solved the problem. does your idle fluctuate up and down? if so i would say throttle position sensor. if not, MAF sensor maybe. a vacuum leak some where could cause similar symptoms. good luck, sorry for rambling
  • 1998lincoln1998lincoln Member Posts: 108
    edited May 2010
    the engine temperature sensor! It will fail, so it will tell the throttle positioning sensor that the motor was cold so it kept dumping allot of fuel. So when the gas was pushed it flooded it and it would die! Problem solved!!
    Let us know if this helps you, These autos are having this problem !
  • pete114pete114 Member Posts: 2
    I have a 2000 Silverado 4.3 v6 I had problems last year with intermittent stalling then, it completely died. The mech replaced the fuel pump....ran fine for 10 months now it went back to intermittent stalling then it died again, mech replaced crankshaft timing sensor, rotor cap and the actual rotor i think.
    It died two miles from garage on the way home...back to mech he said it was a loose battery cable not giving enough spark to plugs.
    It ran great for 2 days back to intermittent stalling.
    it does it while idling or running at highway speeds it seems like it stumbles a little.

    Any help please?
  • pete114pete114 Member Posts: 2
    I cleaned out the throttle body which helped a little.
    The next day it wouldnt start...I found that the rotor was somewhat corroded so i cleaned it.
    It fired up but we noticed that the spark from the coil seemed weak, so I replaced that.
    This morning it idled fine so On the road it missed a little until it died completely.
    Now I have no spark whatsoever from the coil and the ignition module tests fine.

  • tom467tom467 Member Posts: 1
    Hi I have researched the forum and worked on this problem but there seems to be so many possibilities I'm hoping someone can narrow it down. My GMC seirra (2001) with a 4.3 V6 has developed the following problem over the last week. At first there was a very slight surging when driving at steady state throttle. This has now become a massive surging that resembles applying and removing half throttle at 2 second intervals while the throttle is actually held steady at half throttle. The interval between the engine running fine and having no power at all is very repetitive and continues no matter what speed. I have removed and cleaned the cap and rotor, checked plug wires and the TPS. I have changed the fuel filter. The p0300 code is set when driving under hard acceleration and massive surging. It seems to me that the ignition is turning on and off. When" on" all cylinders are firing, when "off" no cylinders are firing. Any suggestions would be very appreciated.
  • redi_jediredi_jedi Member Posts: 9
    my 99' k1500 with a 5.7 died at random, i replaced just about every sensor under the hood. cap and rotor, plugs and wires, coil, ignition module, map sensor, crank sensor, still nothing. one day it started doing what you are describing, i replaced the fuel pressure regulator and it hasn't done it since. I dont know if that is your problem but it would be worth checking in to.
  • 08gmblewup08gmblewup Member Posts: 3
    Here's the deal, a couple weeks ago my 2008 Silverado with 60,000 miles decided to blow - or more appropriately, decided to drop a valve 4 hours from home. It lost all power, started throwing messages, started ticking (obviously the piston slapping the valve) and started smoking white smoke.

    So under warranty, they towed my vehicle and replaced the engine. I got the special treatment of getting a 99 Lumina to drive! I picked it up several days later (on a Friday) with a new engine and headed home. All was fine for about 30 miles. Then the emissions light came on. I pulled into a parts store and had them scan my codes - P0171 and P0174 - right and left banks lean. I had them reset the codes, thinking it was a glitch with the new engine...30 or so miles later, got the code again.

    I called the dealer Monday and explained the issue, to which they told me, "that's an emissions issue, unrelated to the engine and not under warranty"!!!!!!!!!

    So I reset it again...and again it came on. Then I drove it about 100 miles and it went off...then another 30 or so and it came back on....

    Since clearly I wasn't going to get any satisfaction from the dealer (4 hours away), I decided to call Warranty customer service...explained the issue, started getting the "it's an emissions problem not covered". I asked to speak to a supervisor that couldn't be found, was told one would call me back...waited for 4 hours...and had the original person call me back.....

    "Sir, I spoke to the dealership service department and they said it wasn't related to the engine" UGGGGGGGGGGGHHHHHHHHHHHHHHH

    Long story short...Ms Customer service explained over and over and over that an O2 sensor is "different" from the engine...she couldn't understand how a trashed valve, or heavy smoke, could have damaged/fouled an O2 sensor!!!!!!

    So..once I get this fixed on my dime, I'm trading the POS in...I guess there's a reason FORD is the #1 selling truck...I just wish I had listened to the ads...and wish my tax dollars hadn't been part of GM's bailout since it's going to be short lived!

    Sorry for my rant...I've loved this truck...but the "Customer Service" blows!
  • wmazwmaz Member Posts: 3
    There are horror stories like yours with every major auto manufacturer. I've had problems with all of them. Chevy, Ford, Dodge, and finally Toyota. Getting a good truck is a crap shoot. My last new truck was a 2006 GMC Sierra. I wish I would have kept it, it was a lease. Sucks that you got stuck with a lemon but don't think that Ford will treat you any different. Good luck with your next purchase. By the way, you are going to loose your [non-permissible content removed] trading that truck in. Been there, done that!
  • madmuddermadmudder Member Posts: 4
    I am looking for info on swapping my 454 tbi out of my new body style 88 chevy truck. i am wanting to put a 350 carb motor in it while i am overhauling my 454.
    The truck has a 454 with 400 trans and the 454 looks like the same as a carb but with a tbi adapter. Did they do this in factory ? If anyone can help i would appreciate any info
  • 08gmblewup08gmblewup Member Posts: 3
    I guess my issue isn't so much with the engine failure as it is with the "after-care" from the dealership and customer service. I work for a major diesel engine manufacturer and despite our best efforts, defects happen. But we take a failure in the field VERY seriously - and jump through hoops to ensure the customer is satisfied and made whole.
  • corkscrewcorkscrew Member Posts: 254
    This link may help you with codes P0171 and P0174:
    Oxygen sensors tend to diminish with age as contamanants accumulate on the tip and reduce their ability to produce voltage.With 60k on the odometer and white smoke coming out of the exhaust, I can see an O2 sensor fouling. You can check a sensor with a digital storage oscilloscope (best way) or digital voltmeter.
    Start by cleaning the MAF sensor and check for a vacuum leak.
  • cowgirl37cowgirl37 Member Posts: 1
    I have a 2000 gmc 2500 misfiring on 2,4,6 but only when you first start in after 10 mins runs fine and will not show or store a code. what fixed your truck maybe its the same problem thanks
  • 1998lincoln1998lincoln Member Posts: 108
    check the engine temperature sensor! If it's failing it's telling the throttle positioning sensor that the motor is cold so it keep's dumping a lot of fuel. So when the gas is pushed it will flood and it will die! Just something to check ! Good Luck.
  • 08gmblewup08gmblewup Member Posts: 3
    So...after getting NOWHERE with "customer service" based out of India and Mexico, it became obvious I would have to seek my own repairs on the new engine.

    Long story short...without thousands of dollars worth of diagnostic equipment, it's hard to determine whether sensors are working right or not. I started by having a neighbor take it in to the local dealership he works for - he got the codes scanned which came up as the same p0171 and p0174 ---but the dealership didn't want to get in the middle of the "argument" and get involved. Using an inexpensive scanner and a multimeter, I started looking at freeze frame data (couldn't see live data) and working though the troubleshooting tree outlined in a Mitchell manual. This isn't ideal - the data is incomplete at best and leads down false roads, but it's all I had.

    I tried to locate an intake leak using propane, but couldn't get a rev....

    First thing replaced - O2 sensors. No luck, just $320 and a 90 mile round trip drive to get the parts.

    2nd thing replaced - MAF sensor. No Luck, another $170 and another 90 mile round trip for parts.

    3rd thing replaced - MAP sensor. Again no luck, a days wait for the part and another $70.

    At this point, started looking for other problems. I didn't have a fuel pressure gauge, but now I do $50 later. No luck (a good solid 60 psi)

    Took a look at the throttle body - a fair amount of residue. Decided to remove it to clean well. While removing a nut off of one of the studs, the stud broke as soon as I went to loosen it. I thought "AH HA!" - figured the flunky had over-torqued the throttle body and it was sucking air. A drive to the local parts stores, then an ACE hardware, I finally came up with a suitable 6 mm bolt to replace the stud.

    Guess luck.

    So...I call my neighbor at the local dealership...explain I've run out of options, replaced or checked everything that could have been a factor...and still no solution. At this point, I willing to pay for it to be smoke tested. I take it in, tested, and guess what: #6 cylinder intake gasket leaking!!!!!!!!!

    In all of my emails and conversations with "customer service", I explained that the Lean Bank on both sides of the engine was very likely intake leaks from the engine assembly at the dealership....a point they continually dismissed as "it's an emissions problem".

    So here I am - $610 in receipts for parts plus 180 miles in driving, 5 days of working on it, looking for parts, researching, etc....and 3 days late for going on vacation (it's a camping vacation and camping at a music festival, all paid for - but I need the truck to haul gear from NC to WNY), waiting on the dealership to get the intake gasket and get it reassembled. Oh, let's not forget the couple hundred miles driving to see if the codes would reset!

    One more thing - the local dealer is fighting to get the repair covered since it was due to faulty installation by the out of town dealership 3 weeks ago, but by "Warranty" standards, gaskets are not covered! LOL

    I suppose it's going to be lawyer time - I doubt I can get Bruce in India or Tom in Mexico to understand any of this....
  • nansenhomenansenhome Member Posts: 2
    Hi everyone,
    I have an issue with '97 GMC with 225,000mi. It started a while ago with a P0300 that would occur intermittently. Then it started to get worse and the truck would shake, like it was cutting out. Currently it will start fine, warm up and then backfire when under light load at lower speed, high-speed cruising (mostly when being very light on the gas - kind or when you back out of it, then it will pop-pop-pop), or when I get off the gas when I reach speed. The truck performs pretty well when I get on it, relatively no hesitation and she has power.

    I changed out the plugs, wires, cap, O2 sensors (upstream), transmission and converter, knock sensor, MAP, motor mounts, intake, exhaust, EGR valve, Evap Purge solenoid, and some more that I know i'm forgetting.

    Bottom line - it's getting worse. I'm thinking it could be a PCM issue or another sensor that feeds the PCM values, because the truck will start and run fine until it warms up, after it goes "closed loop" the problems start kicking in. Another anomaly is that the truck will accelerate fine, that tells me the fuel pump is working well right?

    I'm an active duty Marine and don't have a ton of money to throw at the issue. I decided to take it in the pants and brought it to the dealership here in DC. They kept it for nearly two weeks, never called me or returned my calls and so I went and got the truck back without any diagnosis. I can't afford to be without the vehicle for that long- or suck up the 120 an hour the dealer charges. Any help from you all is greatly appreciated. Thanks in advance for your response!

    Semper Fidelis -
  • 1998lincoln1998lincoln Member Posts: 108
    Just something to look at1994 silverado dies when put in gear and push the accelerator. Otherwise runs fine, it is a 5.7L vortec . Have changed almost everything (complete tuneup} plus the throttle possession sensor. The funny thing is that is the code it is reading. I have put 2 new ones on it, checked all the wiring and plugs to it. I have one person telling me it could be the MAS or the pick up coil. Any ideas?

    Additional Details
    WELL, we got it! Who knew.. It was the engine temperature sensor! It was failing so it was telling the throttle positioning sensor that the motor was cold so it kept dumping allot if fuel. So when the gas was pushed it flooded it and it would die! Problem solved!!
    6 days ago
  • wmazwmaz Member 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.
  • nansenhomenansenhome Member Posts: 2
    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.
  • jojo7676jojo7676 Member Posts: 1
    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?
  • holocker4321holocker4321 Member Posts: 5
    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
  • 06sierra06sierra Member Posts: 1
    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 Member 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 Member 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 Member Posts: 7,841
    Clean or replace your idle air controller.
  • just_truckin13just_truckin13 Member Posts: 3
  • just_truckin13just_truckin13 Member Posts: 3
    Unfortunately my sierra is a later model which does not have a IAC. Thank you for the reply
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