GM Active Fuel Management oil usage

[sab316]

I had a 2009 GMC Sierra and had it tuned by Blackbear performance. It's an all custom tune. You plug the Autocal into your truck (under dash in between your legs) and drive for a bit. Send him the files. He then reads through them, sees how your truck is reacting, asks about towing, gas type, etc etc. Then makes a tune custom to what you want. You can disable the AFM this way as well.

I wanna say it was around $300-$350 and worth every penny. He gets more HP and pep into it as well.

He actually did in-person tuning in Memphis. Flew in from the West Coast and met at Bass Pro parking lot. Plugged his computer in and told me to just start driving normally. He had charts and graphs going everywhere. He could scale back fuel, do all kinds of crazy stuff. Then told me to get on I-40 and get up to speed, mind you this was at 5 pm on a Friday. So we're bumping along about 70 and he looks at me and says "Alright, I need you to get this thing up to about 100. Don't worry I'll pay for any tickets". Needless to say it was sphincter clincher. But like i said worth every penny.

He told me.... If there are 100 trucks on the lot, each truck with tune differently. I would seriously look into it. (Also only tunes 1500's)

http://blackbearperformance.com/

EDIT: Also forgot to mention he put my tunes onto a ECM (basically the computer of the truck) that he got from a junk yard. He flashes the tunes on, and you keep your stock ECM. It switches easily, that way if you ever needed warranty work you can just put your stock ECM back in. I got the tune at 15,000 miles on my truck and sold it at 50,000 without a lick of trouble.

[Blackduck]

My wife's 09 yukon XL started burning oil at 90k miles. Often add a quart or two.

[stevea]

I have the 07 gmc with afm mine has burned 2 qts every 2500 since I hit 40,000 mi. they changed valve covers and several other things nothing worked. gm told me 2 qts in 2500 miles was acceptable (no its not). I recently hit 120,000 miles and while pulling a trailer to oxford all lights came on and truck started missing. I keep a code reader in my truck and it showed misfire on #6 I pulled spark plug and the end was burned off. I replaced the plug still missing. I limped and I mean limped the truck home ran a compression test and nothing on 6. I pulled the intake and heads (very easy to work on) and the exhaust valve on # 6 had a dime size hole in it. I reworked the head and put it back together runs fine now. The one thing I noticed when I tore it down was there is a tube that runs the length of the valve cover just over the pushrods that is your crankcase vent. also there was a lot of oil inside the intake manifold. I seems the oil is sprayed into this tube and then sucked into the intake very poor design. I plugged the tube coming from the valve cover and drilled a 3/8 hole in the oil filler tube just below the oil cap and re connected the vent vacuum line there. now the crankcase vents from an area where oil is not being sprayed from the pushrods. Intake is clean I have put over 10,000 mi on it since the repair. this truck is stronger no smoke and has not used another drop of oil. There is a service bulletin that requires you to remove the oilpan and put a diverter clip on the lifter relief valve that supposedly is spraying oil on the bottom of the pistons causing rings to gum up and stick. you also have to put a strong upper engine cleaner in each cylinder and let sit for 2 hours to clean the rings. I really don't think this is the problem I saw no sign of oil going around the rings it is coming through the intake via the crankcase vent system due to the placement directly over pushrod holes. When I tore the engine down there was a lot of carbon build up on pistons and valves due to the oil eating, this along with a stopped up injector created a lean condition which toasted my valve. Hope this helps.

[deltadukman]

Yuu reckon all of that is for emissions reasons? Is that why these motors are crap these days?

[stevea]

I think its because you have automotive engineers finding solutions to problems that don't exist.

[stang67]

It absolutely stems from Uncle Sam requiring better mileage standards from the mfg. so they implement these idiotic systems to improve mileage 0.5 mpg on vehicles they sell millions of. GM isn't doing this because they want you to get more miles per tank. They do it because govt stds basically require it.

[teul2]

I have the 07 gmc with afm mine has burned 2 qts every 2500 since I hit 40,000 mi. they changed valve covers and several other things nothing worked. gm told me 2 qts in 2500 miles was acceptable (no its not). I recently hit 120,000 miles and while pulling a trailer to oxford all lights came on and truck started missing. I keep a code reader in my truck and it showed misfire on #6 I pulled spark plug and the end was burned off. I replaced the plug still missing. I limped and I mean limped the truck home ran a compression test and nothing on 6. I pulled the intake and heads (very easy to work on) and the exhaust valve on # 6 had a dime size hole in it. I reworked the head and put it back together runs fine now. The one thing I noticed when I tore it down was there is a tube that runs the length of the valve cover just over the pushrods that is your crankcase vent. also there was a lot of oil inside the intake manifold. I seems the oil is sprayed into this tube and then sucked into the intake very poor design. I plugged the tube coming from the valve cover and drilled a 3/8 hole in the oil filler tube just below the oil cap and re connected the vent vacuum line there. now the crankcase vents from an area where oil is not being sprayed from the pushrods. Intake is clean I have put over 10,000 mi on it since the repair. this truck is stronger no smoke and has not used another drop of oil. There is a service bulletin that requires you to remove the oilpan and put a diverter clip on the lifter relief valve that supposedly is spraying oil on the bottom of the pistons causing rings to gum up and stick. you also have to put a strong upper engine cleaner in each cylinder and let sit for 2 hours to clean the rings. I really don't think this is the problem I saw no sign of oil going around the rings it is coming through the intake via the crankcase vent system due to the placement directly over pushrod holes. When I tore the engine down there was a lot of carbon build up on pistons and valves due to the oil eating, this along with a stopped up injector created a lean condition which toasted my valve. Hope this helps.

This is very similar to one of my 2 experiences with this junk. I am using 2gt+ per 3K miles. I had a misfire in cylinder 7, which was a broken lifter. And now, I go in and out of clogged injector on number 5 cylinder. I've been running injector cleaner for several weeks now at the advise of my mechanic, and it's getting better.

[teul2]

It absolutely stems from Uncle Sam requiring better mileage standards from the mfg. so they implement these idiotic systems to improve mileage 0.5 mpg on vehicles they sell millions of. GM isn't doing this because they want you to get more miles per tank. They do it because govt stds basically require it.

This ^^^^^

[Blackduck]

I think there is a fleet standard MPG. that is why there is a huge push for tiny cars like the volt. They help make up for my 1500

[stang67]

It is called CAFE. And if I read it right years ago, it is weighted to vehicles sold. So if they can improve mileage slightly on cars they sell the most of (1/2 ton trucks), it has auch bigger impact than developing an electric car that they sell hundreds of. I'm probably grossly oversimplifying, but pretty sure that's the jest.

[jmh600]

I have a 2007 gmc sierra at 75k miles started burning something like 1 qt/1500 miles or so took it in. After all the test of me bringing it in every 1000 miles they decided to put some kinda deflector plate in? Long story short that didn't work and many more 1000 mile check ups at sunrise Chevrolet in Memphis I finally got a new motor put in under warranty at 105k miles. Pain in the booty..

[stang67]

Bump. At 89k miles, my 2010 Sierra is doing it. Anybody had it fixed?

[ShotgunSP]

My 07 5.3L drinks about 2 quarts every ~3k miles. Pain in the butt is an understatement.

[stang67]

Out of warranty? Or did they say it was within specs?

[mlj300]

It is my understanding that, on these engines when the computer shuts it down to 6 cylinders it creates pressures that are too high forcing oil into the intake resulting in excessive consumption. I have family in the auto business. They tell me that you can change the computer program and disable the active fuel management which is an instant fix to this problem. If you keep these engines running on all 8 at all times they don't have any issues with oil consumption.