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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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#46 of 106 GM Screwed a bunch of people IMO by rednecktroy May 17, 2008 (8:23 am)
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.
#47 of 106 Active Fuel Management by mattbarry6 May 29, 2008 (6:09 am)
Okay, so this may be heresy but active fuel management is the new hype for most cars and trucks. I was looking at buying a new GM, preferably the hybrid Silverado when it hits the market but quite frankly I can't afford a LTZ model (which all hybrids come in) and I can't seem to sell my 1998 Jeep Cherokee 4.0L. So an idea hit me: why not put active fuel management on it.   The proposed plan is to hook up a simple 5V programmable computer chip to 6 relays that shut off selected fuel injectors at 5 minute intervals (Just like Chevy does on its 8 cylinders). This is to operate the front three cylinders then the rear three cylinders intermittently. Its about a $75 dollar system once the relays, wire and board are purchased and about a 4 hour installation (3 hours of which is required for programming the C++ style board), but the hope is to see if active fuel management really makes a worthwhile difference in highway travel.   Right now I achieve about 22 mpg highway (10 city) and have hopes that the old beast can get a few miles more per tank. Will keep you updated on whether or not active fuel management makes a difference on highway travel or if its something we pay more for from factory but get nothing for in return. Personally, a Prius doesn't sound too bad... if you like 76 horsepower and the ability to tow nothing. Replies to this message: branhap (May 29, 2008 8:19 am) rednecktroy (May 30, 2008 4:28 am) branhap (May 30, 2008 9:26 am)
#48 of 106 Re: Active Fuel Management [mattbarry6] by branhap May 29, 2008 (8:19 am)
Replying to: mattbarry6 (May 29, 2008 6:09 am) A few people with custom tuners or a custom tune have disabled AFM. Most people though with an active tune interested in improving MG make it more aggressive. Stock, AFM kicks on when throttle is less then 6%. A lot of people have bumped it up to 10% of throttle and had a noticeable change.   AFM always turns off the same valves though. It doesn't alternate. It also turns itself off after 5 minutes of continuous use to prevent the active cylinders from overheating to much.   In any case, this is my reading forums only. My 5.3L AFM is bone stock. Replies to this message: rednecktroy (May 30, 2008 4:28 am) branhap (May 30, 2008 9:26 am)
#49 of 106 Re: Active Fuel Management [branhap] by rednecktroy May 30, 2008 (4:28 am)
Replying to: branhap (May 29, 2008 8:19 am) Is there anyone with the programmer in central Ohio? thanks Troy. Replies to this message: branhap (May 30, 2008 9:26 am)
#50 of 106 Re: Active Fuel Management [rednecktroy] by branhap May 30, 2008 (9:26 am)
Replying to: rednecktroy (May 30, 2008 4:28 am) I dunno. I've lived in Wyoming the past few years. Haven't lived in Ohio since 2001.   As for tunes, the most popular one I read about is black bear tune. He basically sends you some equipment to plug into your truck, then you send him back the info tell him what ya want and voila. gm-trucks.com seems to have the most info on tuners.   Good luck!   Paul
#51 of 106 Re: Maybe this thread is the one I should have posted this in. [doc_holiday by putterca Jun 05, 2008 (6:46 pm)
Replying to: doc_holiday (Feb 28, 2008 8:51 pm) you can add the DIC buttons yourself for under $60 and about 5 minutes of your time. all you need to do is order the switches and the replacement dash panel that accomodates the DIC controls. the harness to plug the switches in is already installed and just sitting behind your current dash waiting for you to plug into. I had the same frustrations as you and learned that this could be done very easily. Replies to this message: mikef15 (Dec 08, 2008 4:47 pm) obyone (Dec 09, 2008 2:10 am) skimm99 (Dec 15, 2008 7:47 pm)
#52 of 106 6 speed by putterca Jun 05, 2008 (6:50 pm)
don't expect the 6 sped tranny to drastically improve fuel mileage. from my understanding, the design is more to smooth out the shifting through the gears, not necessarily to add a high end gear.
#53 of 106 '06 Silverado Crew Cab by bprepdah Jun 29, 2008 (7:34 am)
Can anyone tell me where the EVAP canister is located on an '06 Silverado Crew Cab?
#54 of 106 Re: 2007/2008 Sierra Active Fuel Management Problems [gmax6] by chevyfan1969 Jul 28, 2008 (9:05 pm)
Replying to: gmax6 (Apr 23, 2008 5:39 pm) Really good post Gmax. After much debate, I just purchased a 2008 1500 Vmax. I was originally planning on buying a diesel, either a Dodge or Chevy, but after thinking about it I backed out of a diesel altogether. I just couldn't make the initial cost ($6500 extra) plus the premium on fuel work out on paper. I can buy ALOT of gas for that amount. Sure, I've heard alot of people tell me that a diesel will work alot longer, but I don't plan on keeping it for 500,000 miles anyway. Anyway, I've put about 700 miles on it so far and am very happy with it. I've read several complaints about fuel mileage, excessive shifting, stutter when going in & out of AFM, and rough idle. First, my mileage sets at around 18 mpg on average which I think is great for a truck that has the capabilities that this one does. If you want fuel mileage, buy a 4 cylinder. There's always trade-offs when it comes to power/ mileage. I thing GM has done a good job at coaxing 18 or so out of it. I was really expecting closer to 13-14. I do have the excessive up/ down shifting when climbing a pretty good hill but I've noticed that the reason that it does that is, when it downshifts, it has enough torque to quickly get it back up to speed, causing it to shift back up. I would suggest if that is a problem, drop the shifter down to 3rd to eliminate the "problem". As far as noticing it going in and out of AFM, it's very slight. The only reason I notice it is because it's a new feeling that I'm not accustomed to yet. The idle is defininately a little rough, but I think it's cool. All ponied up engines have a rough idle that I've been behind. All in all, I think it's a great truck and I can't wait to hook on to my trailer and see what it'll do. Anyway, just wanted to ad to your post. Replies to this message: obyone (Jul 29, 2008 8:24 pm)
#55 of 106 AFM question by jboehm Jul 29, 2008 (12:50 pm)
I have driven a couple of different Silverado/Sierras with the Acitve Fuel Management. One thing I have noticed is that, when sitting at a stop light, the AFM will switch from 4-cyl to 8-cyl. Can someone explain why? (I know that I have seen documentation that that is the way it is suppose to work but I cannot locate a reason why). Replies to this message: tafid (Jul 29, 2008 3:55 pm)

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