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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: fhaines (Feb 13, 2008 9:13 pm) |
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Well, I have the 5.3 on my "new" chevy 1500 2wd extended cab that is supposed to have the AFM. Ive put 22,000 miles on it since memorial day and have yet to achieve anything better than 18-19 (19 on a good day) MPG. BTW, the sticker said 22 hiway. My question for those who know, is if you have the truck without the DIC buttons, how would you know if AFM is active or not? The book says there is a display regardless of whether you have the DIC buttons or not, but fails to mention how one would know. I drive many days from gas station to gas station only touching the brake pedal and ignition when I leave the first station, stopping at the next one. 60-65 mph, cruise on, all highway. I drove 948 miles this week and might have achieved 18 mpg if I rounded it up. I generally get about 400 - 420 miles per tank and my fill ups are between 22.5 - 24.5 gallons. My simple math tells me that if I were to get even 20mpg, I should go 440 miles on 22 gallons of gas. No, I dont see any indication that AFM even exists. The serial number says it has it, the sticker says it has it, but other than that, there is no indication that it exsists or if it does, that it functions. Ive even driven 2 tank fulls with the trailer button depressed only to find the same exact milage. I love the truck, dont get me wrong. It's not the most comfortable for 6 or 8 straight hours, but it's a truck. My question remains. How would one know when the engine goes to 4 cyl. My next question (assuming there is no way for joe truck owner to know) is how would the dealership test it? Can they hook a computer up to it and see it function, can they engage the EFI manually or however AFM works? How can they show me that it is doing what it says it is or for that matter, even show me that it's installed? 18 is ok? Thats 20% off the sticker. What if your wife was in the grocery store, bought $100 worth of groceries, and the store constantly failed to load more than 80% of those groceries in her trunk? What if you bought an air conditioner rated at 16 SEER only to find out it was a 13 SEER? What if the fuel stations only delivered 80% of the fuel the pump said it did? All I want to know is... Is it there, and if so, does it work (show me). It's a shame a coworker who has the same truck except his is 4wd and he gets over 20 per gallon with the same monthly miles and same type of driving. |
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is there a fuel pump in the single gas tank for a silverado 3500 duramax 6.6 ? also any suggested ideas on what to do when the truck doesnt start when it's cold or hot, mostly cold ? |
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This is my 5th truck which I ordered from the dealer in Maryland and picked up in January 08. After driving it about 200 miles I proceeded to drive to Ft Pierce, FL non stop. Generally speaking, I drove 5 to 7mph over the posted limit e.g. in a 55 zone I drove up to 62, in a 70 zone I drove up to 77.....almost always on 'cruse control'.......my average for the trip was 18.4 mpg and the truck performed flawlessly. I now have 6000+ miles on the truck and it consistently 'averages' in the 16-17 area (mostly short 'around-town' runs). I find that the AFM is NOT noticeable by passengers but IS noticeable by me....though now I find I'v become oblivious to it!! This truck is a 5.3L, 4X4, LTZ with Stabilitrak. My last two trucks were a Dodge 2500 Diesel and a Chevrolet 2500HD Diesel respectively.......this '08 truck is far more economical than the Dodge and equal to the Duramax, though, I'm sure, it won't tow as much....its all a balancing act....the diesels are a $10K additive cost and the diesel fuel is 12 to 15% more expensive than regular......bottom line is that if you are not towing high weight trailers frequently it is far better to go with the gas truck! Prior to the Diesels I owned a Nissan and a Toyota.......wasn't happy with either of them!! |
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I have a 2008 chevy silverado with a 5.3 and active fuel management. I am wondering if there is a way to tell when the truck is running on 4 or 8 cylinders. Can you hook up a test light or something to that effect,
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| I have heard that there is an issue with the Fuel management system when you put on a duel catbak exhaust. When it shifts to 4 cyl it makes a roaring sound? is this true and if so what luck has anyone had with finding one to put on an 08 silverado 1500? | |
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Replying to: tomkronberger (Apr 06, 2008 7:02 pm) |
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Replying to: canw (Jan 21, 2008 8:28 am) How can you see a difference in what you get as far as every day performance? I suggest you run the crap out of it occasionally. Also, if you are always running regular fuel, don't. Run a tank of premium or mid grade through her every so often. Or just add some to your regular. Right now no one offers a cold air package for them. K&N has a drop in replacement that helps. Few tuners out there too. Hypertech seems to be the best. Diablo just came out with theirs. Gibson has a great cat-back exhaust that helped mine. Sounds great without a lot of in-cab resonance. These alone have helped improve the mileage. But if you are like me you may not be able to keep your foot out of the throttle. I LOVE THIS TRUCK! If it didn't have a speed limiter (at 95) I bet it would pass 150. The AFM system only kicks in under the lowest load conditions. Down hill, tail winds, flat road. When on the highway try setting your cruise control just as soon as you feel it go into overdrive. Set with RPMs at 1500. Should be on 4 cyl. Look at your DIC. Should say somewhere around 24 mpg. Also around 45 mph. But most people can't stand to drive that slow. I can't. So I just drive the way I feel, within the law. HA! Anyway, don't treat that truck like a baby. It aint! You wondering when it'll break in? It wont until you use it. So use it.
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| You have afm,no dic installed,noway to tell if afm is working.For 17,000 miles I complained about really bad economy.Finally the lifters started tapping took it in for service the world class mechanic told me [they all do that piston skirt knock]I argued till he finally listened to the lifter tap.they replaced lifters plugs and wires.reprogrammed the computer,now I'm getting 20 to 24 mpg.But it has developed a mind of its own sudden accellation at stop rpm's raise from 500 to 1200 not all the time just every once in awhile.,\gm tech can't reproduce the problem,gave it back to me and said wait till it does it more often.Had a tick in the windshield,was told the bug deflector was the problem took it off still had the tick,they replaced trim inside the cab.Gas guage was saying less gas in tank,replaced a sending unit,fixed that,then a valve for the evap canister went out,fixed that.Of course I have called gm to,ask for compensation for the 17000 miles of 8-9 mpg they said no,I asked for the dic button to be installed,they said that is a dealer option,dealer said"As long as it does'nt cost more than a$100,they would cover it.Why would they say you have afm but no way to show it working,cuz they get $600. for it free,I have 87 chevy sitting in the garage it does a 11 second 1/4,at 112mph in four wheel drive,I've built a bunch of bowtiesbut this 2007 silverado has yet to impress me,nor has gm at this point. | |
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