Active Fuel Management

[ARMYDUDE]

I've checked a few aftermarket products but they run from $250 - $500 and will void the warranty. I AM ON A CRUSADE FOR GM TO FIX!

[onebadbowtie]

Superchips my friend Superchips.

[ARMYDUDE]

Will superchips de-activate the AFM??? or just give the AFM better performance? I want the AFM GOOOOOOONE!

[ozzyjacob]

I have a 2008 sierra 5.3 with afm and I havn't had any problems but I did chang my exaust to magnaflow duals and it sound fine in v8 mode, but when cruising for awhile and v4 mode kicks in it sound very poopy basically like a four banger with duals. It can be kind of annoying on a long trip

[ponchoman49]

I have a 2008 Impala 2LT with the AFM 3900. It idles and runs perfectly. But I can instantly tell when it is in AFM mode. The engine has a slight shuddering sound that can be heard and felt almost as if something was out of balance. My car has 44K miles and I have driven other 07-08 Impalas with this same engine with lower miles that are hard to tell when in 3 cylinder mode. I'm wondering if normal engine wear, degredation of the plugs/wires, carbon etc will affect the operation of 3 cylinder mode because it would seem to me that this engine would have to be in tip top tune to get away with running smooth in 3 cylinder operation. I also notice that when caught up in 3 cylinder mode if I need a sudden burst of power there is a slight hesitation before the power comes on. I have yet to determine if this is caused by AFM or a faulty drive by wire unit. My buddy is going to hook up his scanner that monitors every function and see if there is something that can be traced.

[Wolfman01]

I have the AFM engine, and love it. I've had no issues with it at all. Like Ponchoman, I can also tell when it is in V3 mode at lower speeds. It sounds like it's lugging a bit with just a tiny little bit of a sensation of the individual cylinders firing. It's not annoying to me, just noticeable. I can return crazy fuel economy numbers on pump gas on the highway. Just look at my sig.

[Packrat33]

Originally Posted by ZZ71

I got a 2008 GMC Sierra SLT E. Cab Z71 with 11,000 miles and have an ongoing problem with AFM for the last few months. My truck vibrates/shudders when its in V4 mode. Dealer people and I both drove an identical truck and it did not do what mine is doing.

They found NO codes set or anything wrong. A search found a TSB relating to a check ball in the trans that sticks and will cause a harsh TCC lockup and vibration when in A4 mode is so equipped (2005-2008 trans).

Whenever the V4 mode engages at lower speeds (whenever you let of gas at less than 40mph) and you have to maintain constant speed, the engine vibrates (or shudders as I call it) it does not switch to V8 mode right away, you have to give it more gas to make it switch and then you risk the chance of rear ending someone in close traffic. Kind of like with a carb where the accelerator pump was faulty and you stepped on the gas and nothing happened but then suddenly it went.

The SM is calling in to GM tech line today tp see if they can find a solution.

Dealer will not disable AFM but Wester's will for $595.

Btw - All the talk about AFM being good for mpg, I am only getting in the mid 16's with this, best on the highway is 18.1. I never speed or hotrod, rarely drive over 65mph. My 2004 got this mpg so all those who claim over 20, I don't see it with my truck. My truck was built in June of 2007.

I feel like you took the words right out of my mouth. I have been describing this crappy system exactly the same as you have with the vibrating and shuddering as if it is a carb with a bad accelerater pump. What more have you found out on this problem, if anything, since you posted this? What is the deal with "Websters" that you mentioned above for $595? I am to the point where I will pay just about anything to get this faulty system turned off/de-activated. Let me know if you have more---Please.

[Packrat33]

I am with you-----------Every time I take my vehicle into the shop for any type of warranty repair I make it a point to have them try and repair this crappy AFM system. It sucks.

[2009lt1]

Originally Posted by ggcurtis

I can not believe what I'm hearing, I have a 2007 silverado that has been in the shop 3 times due to what feels like a misfire but no check engine light. Had the service manager drive and he said we had a problem but when the head mechanic connected to the ECM and drove it down the road with me he showed me that tremendous jerk I was feeling was the cylinder activating. They have had several complants on this and have contacted GM engineers on this one due to all the vehicles having the updated software loaded.

I have a 2009 with the 6.0 and 6 speed tow package and I have had this problem since day one, it now has about 4k mi. Even when hot, the engine sometimes shakes when stopped at a light. The dealer put injection cleaner in it because they couldn't find any other TSB, but it did not help. There's alot on the web on this and apparently GM can't/won't fix it. Apparently A PCM tune will but it voids your warranty, I'm told. It adds stress to the driveline by shutting down when letting off the throttle and stepping on it again...feels as if there's driveline slop but it's just poor engine performance. Sometimes causes bad shifts as well. Don't know what to do...this is my 5th new silverado since '99; I love 'em but this might end it. Any good techs out there with a solution?

[06MonteSS]

Armydude... get a diablosport Predator (model U7194) and be done with the AFM/DOD for good! You can turn it off/disable it completely - plus, you'll gain 15-20hp/tq with their performance tune to boot! (even more giddy-up once you get your fueling dialed in, or even get a custom tune!!)

I've had it turned off/disabled in my monte for over 3 year now, and no issues since...

AND, my mileage actually went UP without it....