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2007/2008 Silverado and Sierra Active Fuel Management Problems

106 messages,  Last post on Sep 01, 2009 at 9:04 PM

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What is this discussion about? GMC Sierra 1500, Chevrolet Silverado 1500, Fuel System, Truck


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#13 of 106
Re: 2007/2008 Sierra Active Fuel Management Problems [1offroader] by tafid
Jan 01, 2008 (9:03 am)
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Replying to: 1offroader (Dec 26, 2007 8:36 pm)

1offroader
Thanks for the comment. I am not the one who said my sudden accel issues was caused by the active fuel management system. The company (Chevy) told me that the reaction I am getting is normal with all Silverados with AFM. I agree that there seems to be another issue, but no one will listen or acknowledge it. As I was verbally told in the beginning of my attempt to get his resolved, there is no calibration for this issue 'at this time'. So I am stuck with a vehicle not functioning properly. There are no safety concerns and therefore no urgency on their part.
 
tafid
#14 of 106
Re: 2007/2008 Sierra Active Fuel Management Problems [tafid] by 1offroader
Jan 01, 2008 (5:39 pm)
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Replying to: tafid (Jan 01, 2008 9:03 am)

tafid
I don't care what the Chevy dealer is telling you, it isn't true. I don't experience any of those symptoms. Nor do most other Silverado owners. The dealer may just be trying to get out of fixing it. Don't allow that to happen, stand your ground and get it fixed.
 
A vehicle surging forward unexpectedly, such as you described in your earlier post, is most certainly a safety issue and you should present it as such.
 
1offroader
#15 of 106
Re: 2007/2008 Sierra Active Fuel Management Problems [santaman58] by natesms
Jan 18, 2008 (9:28 am)
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Replying to: santaman58 (Nov 26, 2007 12:45 pm)

I recently bought a 2008 Max with the 6.0 and I have the same concerns that you posted here. I have a rough idle (it seams low to me to, 450 - 500 rpm when in gear and stopped). The RPM's bounce around a little when you are sitting at a stop light.
 
I also have the same tugging issue when you go up hills. That one really bugs me, you have to give it some gas to get it to downshit to make it stop. There is also no question when AFM is kicking from 4 to 8. You feel it, even at highway speeds.
 
I just got this vehicle so I'm hoping the computer learns over time, but I'm not convinced. I test drove a 5.3 version for 3 days and loved it. Didn't have any of these issues at all. Everything was smooth as could be. When my 6.0 got to the dealer, I hoped in, ran around up the highway and back and bought it because of my fantastic experience with the 5.3. Now that I have it at home I'm really starting to get concerned. Does anyone else have some insight on their experiences? I'm not jumping to conclusions yet as it only has 200 miles on it, but these things have jumped out at me compared to the 120 miles I put on that 5.3.
 
Also, fuel mileage. Anyone able to get anything close to the sticker on the window? I ran 35 miles on flat road at about 60 - 70 mph and averaged 13.4...holy crap!
#16 of 106
Re: 2007/2008 Sierra Active Fuel Management Problems [1offroader] by tafid
Jan 19, 2008 (5:53 pm)
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Replying to: 1offroader (Jan 01, 2008 5:39 pm)

1offroader
Thanks for the support.
I even tried going through BBB Autoline to get help. Thought they could help mediate. But the BBB Autoline is funded via the auto industry. They say they are impartial, but.... I am trying other approaches, like this forum. Someone knows there is an issue, or that this is not NORMAL.
BBB Autoline makes you prove there is a problem. So it is you against the auto company.
I am a customer who is not satisfied, though GM says customer satisfaction is important to them. I'm sure.
 
tafid
#17 of 106
Re: 2007/2008 Sierra Active Fuel Management Problems [natesms] by 1offroader
Jan 20, 2008 (4:03 pm)
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Replying to: natesms (Jan 18, 2008 9:28 am)

natesms
Your mileage is horrible, there is something wrong. Doing 70 mph on flat fwy. I expect 18 mpg. I have gotten as high as 18.5. No foolin, done it many times. Of course thats assuming you are not hitting the throttle hard getting on the fwy. etc. Even so, in bumper to bumper commuting traffic I get 15. The weird surging and the bad mpg may be related. Don't accept what the dealer is saying.
 
As to idle, mine fluctuates a little but that doesn't bother me, it's a truck not a Benz. As long as it doesn't make me spill my beer it's not excessive.
 
1offroader
#18 of 106
Re: 2007/2008 Sierra Active Fuel Management Problems [1offroader] by natesms
Jan 21, 2008 (6:33 am)
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Replying to: 1offroader (Jan 20, 2008 4:03 pm)

1offroader,
 
Thanks for the comments. I went out this weekend and put another 250 miles on it to bring my total up to 500. I did another 15 mile run at 65 - 70 mph and my mileage was up to 15.5. I think I'll give it another 500 miles and see where I am at, it might really just need to break in some more.
 
The idle doesn't bother me, I just noticed it because my old F150 never so much as shuddered. If it was shuttering it meant yet another coil pack went out (stupid, stupid design, first thing I did with this truck is pop the hood and make sure something similar didn't exist. Looking forward to being able to park this truck in a rain storm without fear).
 
I must say I do not like the AFM very much though. It is noticeable when it turns on and off. After some more research this seems to be normal and a common complaint among owners. From other things I have read it seems to be more prominent with the 6.0 than the 5.3. On one website, out of 6 reviews it was listed 6 times under the cons section, but often with a note that you get used to it. The thing that is weird to me is that I get a "surge" (acceleration) when it goes into v4 mode, the switch back into V8 mode is smoother. I would think it would be the other way around.
 
I'll post my mileage again once I hit 1000 miles, and any other developments along the way. It'll probably be 2-3 weeks unless I decide to take a road trip next weekend.
 
natesms
#19 of 106
Re: 2007/2008 Sierra Active Fuel Management Problems [tafid] by natesms
Jan 21, 2008 (6:41 am)
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Replying to: tafid (Jan 19, 2008 5:53 pm)

Tafid,
 
In my limited experience with this truck I have yet to experience anything like what you are describing. I agree with 1offroader about sticking with this until you get it resolved. I'm amazed that they don't see it as a safety issue. Have your buddy call them after he gets pancaked between the bumper and a trailer as he is guiding you back...
 
Keep us posted.
 
natesms
#20 of 106
Re: 2007/2008 Sierra Active Fuel Management Problems [natesms] by canw
Jan 21, 2008 (8:28 am)
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Replying to: natesms (Jan 18, 2008 9:28 am)

Santaman: Yep, I've got an '08 Silverado VortecMax 6L that I bought in Aug. 07 with the same issue. Dealer says everything runs up to the computer spec so it is "just the nature of the beast." When I got nowhere with the dealer, I went to GM and their tech people say the same thing; "the rough idle I experience is normal for that vehicle." Like you, I didn't notice this issue until about 200 miles on the odometer and my name was already on the bank loan. Too bad for me I guess. And yes, the AFM delivers about 13.5 mpg on my truck too. I'm sure that doesn't help GM's fleet average.
#21 of 106
Re: 2007/2008 Sierra Active Fuel Management Problems [canw] by 1offroader
Jan 21, 2008 (9:32 am)
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Replying to: canw (Jan 21, 2008 8:28 am)

All
I do not understand where all the lousy mpg is coming from. I get an honest 18 on the fwy. at 70 mph, in cruise control. Maybe that is the key, having it on cruise control.
 
As to the afm, I have had a friend try to tell me when he thinks it goes from v8 to v4 while riding in the passenger seat, he can't do it. I can tell, just barely, if I am driving because I have a foot on the throttle and it is just barely noticeable if I am concentrating on it. Otherwise not.
 
Genuinely sorry for your problems, but do not let the dealer tell you that surging is not a safety issue, it most assuredly is a safety issue. Get it fixed before someone gets hurt.
 
1offroader
#22 of 106
Re: 2007/2008 Sierra Active Fuel Management Problems [canw] by ponch1
Jan 21, 2008 (10:07 am)
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Replying to: canw (Jan 21, 2008 8:28 am)

Hey everyone! Im new to this post, and let me share my experince with my 2008 VortecMax with everybody...I bought this truck 4 month's ago, and like some people on here I thought that this "rough shaky" idle I am experiencing would go away after a few hundres miles, I too thought it was the computer going through a "learning mode". After 1000 miles I took my truck back to the dealer, and had them try and diagnose this problem. They ended up doing a computer upgrade (crankshaft position sensor relearn). I got my truck back and it ran absolutely the same as before, I would have turned right around and gave it back to them, but I needed my truck that day, and didnt have time. I took it back a few days later, and told them to not call me until this problem was fixed correctly.... so I get a call from the dealer, and they inform me that they called general motors, and that GM is saying "this is a normal characteristic of this engine". I was dissatisfied, so I looked in my owners manual for the 1-800 number to GM customer service, and wanted some answers as to why this is normal. Let me tell you people that this was a COMPLETE waste of time for me. They wont get on technical terms with you, or connect you with someone from an engineering dept, instead they give you a mailing address to write to in detroit. I went that route, and sent a letter to them 2 MONTH'S AGO, and never received a call from them. The only thing they did for me was send out an area rep from GM to look at my truck's problem at the dealership. This clown cared more about getting home because he was tired, and told me more about his personal life etc...bla..bla., and didn't care one bit that I was dissatissfied. They tried to keep me happy by extending my warranty for free, but that does NOT fix the problem. I then wanted my money back, and was gonna hand them the keys, but I was told that I cant do that, and that I have to go through a long drown out process of contacting a lemon lawyer, and other things. I also learned that you should NEVER sign an arbitration agreement, when buying a vehicle, (which I signed accidently). All in all, I am DONE with general motors...mainly because of their terrible customer service,...I will continue to tell as many people as I possibly can to buy from someone else. I dont even care about the gm discount which I qualify for anymore, I am done!! I have been a loyal gm owner ofr years, but they really pissed me off now.... Good luck everybody.

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