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Pickups Chevrolet Silverado & GMC Sierra 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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Replying to: cadillac5 (Oct 17, 2007 4:08 pm) 
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Just purchased 2008 Z71 Siverado 1500 5.3L 3300 miles both sensor causing engine hot error and fuel sensor back ordered, problem seems to be wide spead and cold related accordin to local dealer in Anchorage 
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Replying to: cadillac5 (Oct 17, 2007 4:08 pm) When easing to a stop or after stopping and slowly rolling (by easing off brake, no throttle apply) into my garage, the engine speed will increase surging the vehicle forward. It does not matter if the engine is cold or warm, nor driving for one minute or one hour. The engine speed will increase up to ~1000 rpm or more. The engine speed will surge and slowly come down to ~600 rpm in less than 15 seconds. This problem does not occur all the time, but I can bet on it happening each time I drive. This condition is known and called normal (by GM) with Silverados with AFM. I tried to get someone at Chevy to see that a vehicle accelerating on its own is not right. No luck. They don't talk to you, they send customer service to deal with you instead. So I will need to live with the condition and hope the sudden accel does not get someone hurt.
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Replying to: tafid (Dec 20, 2007 4:17 pm) I have AFM on my 2007 Silv. w/6.0. It doesn't do anything like you describe. In fact, AFM 4 cyl. mode does not even engage at speeds less than about 15 mph. I think it is WAY premature to blame your problem on the AFM system. It could be a malfunctioning engine control module, a sticky throttle body, etc. There are many things it could be besides the AFM. I am in no way downplaying your problem, just pointing out it very well may be unrelated to AFM. Good luck solving the problem, please post when you do. So far at 13K no problems, I like my Silverado. It's not perfect, but what is? It's the best 1/2 ton truck out there now, for a while anyway, at least until the Ford and Dodge re-design in a couple years. 1offroader
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Replying to: 1offroader (Dec 26, 2007 8:36 pm) 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
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Replying to: tafid (Jan 01, 2008 9:03 am) 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
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Replying to: santaman58 (Nov 26, 2007 12:45 pm) 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!
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Replying to: 1offroader (Jan 01, 2008 5:39 pm) 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
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Replying to: natesms (Jan 18, 2008 9:28 am) 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
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Replying to: 1offroader (Jan 20, 2008 4:03 pm) 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 |
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