Diablosport Forums

I have a 2007 Classic Silverado with a 5.3 in it. 8th digit in the VIN is a "T". I need to know if my truck is infected with AFM and if so how can I disable it? It's being reported that Chevy's are burning oil like mad when they start hitting about the 40k milage mark. On the order of 1qt every 2k miles. The suspected culprit is that when these engines kick into 4 cylinder mode oil is getting up above the pistons of the inactive cylinders. And that major damage is happening to the rings and the valve traind along with it. GM's position is either 1qt every 1k miles is ok or they go and install some type of splash guard up inside the pan. Others are saying that disabling AFM is the better solution as the oil problem goes away when done. Any help would be welcome.

that TSB/issue is only for the engines with the aluminum blocks...

and you don't know if you have AFM or not??? does your DIC show you if it's in 8 or 4 cyl mode?? look on your black engine cover - it would say Active Fuel Management right on it, hehe....

I'm pretty sure you DO have it...

Well, I'm leaning that I don't have AFM. My DIC has never shown 8/4 mode. On the engine cover it only says "Vortec" and nothing else. Owners Manual says nothing about AFM anywhere. I'm pretty sure I have an Iron block to boot. According to Wikipedia Vortec engines with AFM were first produced in 2005. But more important is the fact that non AFM engines were used up until 2007. I'm thinking that I may be lucky and have one of those non AFM engines in my truck.

yeah, you have nothing to worry about... iron block...

afm is only in the new body style 07 and up trucks. you have a classic so you wouldn't have afm.

07 classic and before=gen3 engine=no afm.

07 nbs and up=gen4 engine=afm.

I have an iron block 5.3 with AFM that has had the AFM kiwis cut off by the diablew tune.

Though the TSB covers AL blocks, and all the incidental info I have heard seems to FAVOR AL blocks in terms of excessive oil consumption, mine is not burning any oil. The AFM system was active up until about 40,000 miles.

I have heard of some with iron blocks complaining as well.

I say turn it off either way. I haven't noticed a bit of difference, in fact, drivability is better, engine is smoother, and it seems fuel economy is up slightly.......

Just put a lift, bigger tires and a trailer on and the only time you will see 4 cylinder mode is in your dreams

of course, that is a SECOND alternative