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2011 Chevy Silverado 1500 Rough Start

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I have a 2011 Chevy Silverado 1500 with the 4.8l V8 and have
recently been encountering a problem with it. When I go to crank the truck, it
half way cranks, then fires and the engine bogs down to about 200 rpm's for a
second or two then jumps up to about 1200 rpm's normally then slowly levels out
like it should. There’s no other idling problems that are happening. It runs
normal after that happens when I first crank it. It's not causing the check
engine light to come on either. It seems to do it worse the colder it is outside
but it only does it when the engine is cold. After the first start in the
morning, it won’t do it unless it sets for about 8 hours or so. It's almost as
if I was letting go of the key too early when cranking but that’s not possible
on these trucks because they have a set cranking time that you can't control. I
run good quality 87 octane gas through it. I have also tried fuel injector
cleaner and fuel treatment but that hasn't changed anything. Could it possibly
be the e85 sensor that adjusts the amount of alcohol to fuel ratio to the
engine? Someone else said it could possibly be the camshaft sensor because it
sounds as if not all the cylinders are firing during cranking. Or could it be
the fuel pressure in the system because after it sets for a couple of hours it
does the same thing. I made sure the fuel pump was working fine by listening to
it as I switched the truck to the on position. Would the battery have any effect
on it because I checked the battery before cranking and it read about 12.1 volts?
The meter on the dash reads about 10 volts before cranking the truck by just
switching it on. Once it cranks, it reads above 14 volts when being charged by
the alternator. It has the original battery in it still, and the truck has a
little over 59,000 miles on it. It has really been bothering me because this is
the only problem I have had with the truck, so I will probably be taking it to
the dealership this week to have it looked at. I haven't really heard this issue discussed
anywhere online, so was going to check here to see if anyone knew any
suggestions before taking it in. Thanks!

Here is the link to the video on YouTube that I recorded of having the problem.


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Mine is doing the same thing. I've seen somewhere about the e85 sensor and someone told me it might be the battery is getting weak and doesn't quite have cold cranking amps it needs. I'm in the same boat, I don't know where to turn with it because the dealer wants 100 bucks just to hook it to a computer to check the sensors.

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My 2011 with the 4.8 is doing the same thing but not as bad. When I start my truck, the rpms bog down to around 400 and then roars up to 1200 and it stumbles in between 900 and 1200 rpm for a few seconds and then normals out. This just started happening recently when the temperatures are below 30 or so. I am guessing the battery is getting weak and that is all it is. The factory batteries in our trucks are known for not lasting much longer than 3-4 years.


Because these trucks have computer controlled ignition systems, they behave differently when the battery gets weak compared to traditional switch style ignition systems. Traditional switch style ignition systems will give the very common weak starting sound with a weak battery; "chiga, chiga, chiga, chiga...vrooom" type sound. The more advanced ignition systems our trucks have probably send all the amperage the battery has to the starter in one pulse, thus causing our strange starting and rpm fluctuation problems, until the power builds back up in the battery.


This problem really doesnt worry me too much but if it did, I would test the theory by hooking the truck up to a strong jump pack or jumper cables when it is cold. Wait for the next really cold day when the engine has sat for a while, hook up the cables and start the truck. If it starts more normally than before, you can bet the battery is the culprit. As an alternative, you can go to autozone or advance auto and have them test your battery with their machine and that should give you a good idea if the battery is weak.


If you do find out your battery is going bad, you could go ahead and replace the battery right away or wait untill the battery gets so weak it has serious trouble starting or wont start at all. This is the time of year that car batteries have a lot of trouble and frequently get replaced. Trust me, you are not the only person having these troubles right now.

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Well I tried hooking up the charger on it to top it off before I cranked it early in the morning. It didn’t really change anything. I also took it to two auto part stores (O’reilly and Advance) to get them to check out the battery. They both hooked their machine up to it and told me that the battery, starter and alternator are all in good shape. The guy at O’reilly’s said it could possibly be the battery but he wasn’t sure. The guy at Advance said that it might be a sensor that adjusts the air to fuel ratio. That brief pause in the rpm’s could be where it is trying to get the right combination, but concluded that it’s not normal. So that lead me to breaking down and taking it out to the dealership. I talked to one of their technicians and he told me that it’s probably not the battery because once the engine fires, it no longer relies on the battery. He said it could be something to do with the throttle body or some sensors, in other words he wasn’t really sure. So to come to conclusion, I had to leave it overnight to let the technician go out in the morning to crank it to see if he can come to a conclusion on what the problem might be. I’ll keep y’all updated to what they find out is wrong.

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GMT-900 trucks are currently having many problems with throttle position sensors and notices of it were recently mailed out. That could be the problem and if it is, the dealership will replace it under warranty. Worst case scenario, the dealership starts your truck in the morning, it starts normally and they give you your truck with a reciept saying "could not duplicate problem". Keep us updated.

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Well got my truck back from the dealership with no fix. The technician cranked the truck early in the morning and he said it was obvious what the truck was doing. They were able to duplicate the problem but were left clueless. They said they hooked it up to their diagnostic machine but everything checked out good. They said the battery was fine. There were no codes or sensors showing any problems. That left them to calling General Motors technical support. They suggested to them that they need to clean the throttle body and the fuel injectors and that MIGHT fix the problem. They said older model trucks have had similar issues and that is what they did to them. So they wanted to charge me 330 bucks to clean the throttle body and clean the fuel injectors. They said this was to get around having to replace the throttle body, BUT they could not guarantee that this would fix the problem. They were just giving me suggestions of what they think it could be. A fuel injector cleaning is the biggest waste of money to me because in today’s cars, fuel injectors don’t get dirty due to the amount of ethanol in the gas. You can just do the same thing by adding a bottle of injector cleaner to your gas. Then the throttle body does get dirty, but in a truck that new, I don’t see that being the cause of something like that. They told me that I should get the throttle body cleaned every 30 thousand miles. I don’t think that’s the problem because the truck is not showing any signs of it being the throttle body. I can clean the throttle body myself by scrubbing it out by taking the intake tube off which I may end up doing. I just don’t see paying that much for a cleaning service that they can’t guarantee will fix the problem. So 93 dollars later for paying for them to hook it up to their computer to find nothing I’m back with the same problem. They said it’s not a real serious problem, but could develop into one if it was the throttle body. I guess I’ll have to put up with it until it shows more symptoms or gets worse. So now I don’t know what to try, anyone got any other ideas?

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I have been driving my truck more lately and sure enough, the engine hasn't been acting strange on start up anymore. I am chalking my problem up to the fact that it was very cold and the truck sat for a few days before I started it. Where are you from and how cold has it been outside? I am guessing the cold is what is causing the problem.


I kinda figured you would get that response from the dealer. It is more of a just a nuicance and not throwing any codes so they can't fix it under warranty and don't want to promise you a good repair.


I would just take the dealer's advice and add a bottle of Techron fuel system cleaner in your next tank or two. You can clean the throttle body and throttle plate by disconnecting the intake tube, put the key in the ignition, turn it to "on", have an assitant step on the gas and then spray the throttle body with throttle body cleaner and scrub with a rag. Doing either of these jobs is just basic maintaince and wont hurt anything. Best of all, it wont cost you much to do or take very long. I would just give it a try and see where it gets you. Other wise, dont worry about it and blame it on the cold weather.

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  • 1 month later...

Your truck is a lot newer than my Suburban, but only has 10k less miles than mine, so I'll throw-out the need to check for a leaking intake gasket. Mine ran rough at start-up, especially in cold weather. $450 to repair but did solve my problem.

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