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3.9L Active Fuel Management Decativation

70K views 49 replies 28 participants last post by  JD4ever16 
#1 ·
For the 3.9 L engines (RPO codes LZ8 (vin "R") and LZG (vin "3")) in the 2007 and 2008 Impalas the AFM lifters are no longer being manufactured so as a result GM has released a TSB #13-06-01-002 on 6/26/2013 detailing on how to convert the engine to a non-AFM engine. All it requires is a conversion kit part# 19299225 that contains the parts necessary to do the conversion and a special code to get the new ECM calibration that is also required. The parts in the kit include a new camshaft, lifters, lifter guides, and a LOMA oil block off plate.
 
#2 ·
Good info, such a shame though, the 07-08 LTZs get very good mileage on the highway when running with AFM on.

In my casual daydreaming, I'd had thoughts of putting an AFM equipped 3900 from the wreckers into a lighter Malibu Maxx SS for a more fuel efficient daily driver.
 
#3 ·
Most reports say there is only a 1-2mpg gain with AFM, doesn't seem worth it to me with all the oil consumption problems that come with it.
 
#4 ·
I saw a very solid 1.2L/100km difference on the highway with my Dodge Hemi with their identical version of cylinder deactivation. 1.2L/100km = 3 MPG in US gallons. The system does work, 100%, and not in a totally insignificant way.

By its nature, the current setup will consume oil but everyone's interpretation of how much oil consumption is "an issue" is different. Some people say they have blue smoke puff out the back when the system disengages, that's an issue. Others are probably annoyed that they have to actually their their dipstick levels every month, actually do maintenance, those people I don't sympathize with and its hard to know who just makes a fuss.

I will say, if I could have my 6.2 LS3 in my Trailblazer run in DoD mode on the highway and gain me 3MPG, I would. I guess I'm the minority who like the cylinder deactivation system.
 
#5 ·
I've never dealt with it, only relaying what I have heard.
 
#7 ·
Bart...that's COOL!!

Do you have a link to a readable version, or the dealer printouts!??!
I'll have to get my dealer to print it for me!

As I've babbled here previously, my '08 LTZ 3.9L AFM burns oil at a decent rate. This past winter, I did an oil-consumption test with my dealer. It burned 1.5 Qts. in 3,400 miles. I ran Mobil-1 thru the whole time.

From a "Geek" standpoint, I like the AFM system! Mine switches in-&-out seamlessly. Since spring, I've been using the GM "Full-Dino" oil...no diff. noticed in oil-burning unfortunately...:dunno::bang:....

I don't really care bout gas-mileage, but it WOULD be nice to NOT burn oil!!!!

Faron
 
#9 ·
No problems here with the AFM, yet.

Oil consumption is in the 2,500 miles per quart range - not too concerned about it, given the miles accumulated. When the vehicle was newer (< 50,000 miles), was figuring in the 6-7,000 mile per quart range.

Given the parts listed for the conversion, figure I can buy a whole lot of oil :) On the other hand, should something in the engine fail requiring this conversion, due to lack of available original replacement parts - now that would scorch my shorts.
 
#11 ·
Cylinder deactivation is going to use some oil in its operation. When cylinder deactivation begins, the exhaust valve opens on the final exhale and then the intake valve never opens, neither does the exhaust valve again until that cylinder is reactivated.

In that dead cylinder, as the piston pumps up and down, a vacuum is created, strong enough to draw some oil from the crankcase past the piston rings and into the combustion chamber, which is then burnt off when the cylinder reactivates.

If the consumption is excessive, more than a quart per 2500 miles, I'd try some fuel injector cleaner in several tankfulls of gas in succession, and also add some GM EOS (Engine Oil Suppliment) which will help clean the bottom oil control piston rings. Fuel injector cleaner twice per year is not a bad idea either way.
 
#12 ·
The main cause of the oil-use is the oil-spray on the bottom of the "dead" cylinders, which of course did build up some between the rings, leading to increased oil-burning.

One of the fixes for all the AFM-V8's, besides the top-engine cleaner soak-time regimen, was a new oil-pan gasket with a metal oil-deflector tab that reduced/eliminated oil-spray. This tsb is linked in the forum here somewhere! I've had them printed at my dealer too.

There was never a part/pan designed for AFM 6's like mine though...
Proportionately, my 3.9 burns MORE oil than the V-8's!!!:gaah:

That's why I'm so interested in Bart77's notice of the NEW TSB!!!

Faron
 
#14 ·
I have been curious about also. I have a 08 LTZ with the 3.9L AFM engine. I have no problems with it being noticeable when changing from 3 to 6 cylinders, there is no smoke out of the tailpipe, but it does use oil, not a lot, but like mentioned before, the oil level goes down faster than an 8 cylinder. The crankcase only holds 4 quarts, so it needs monitored. I didn't realize a camshaft change was necessary for a conversion. I have changed cams, but it might be necessary to pull the engine on an Impala? There is a company that has a module that will plug into the 0BD 2 receptacle to shut off the AFM, its $200, and I wonder if it would help that much with the oil using problem? They have some pretty good mechanics at my dealership, I wonder if they ever get a call to do these conversions and what the $$$ would be. I bet it is not cheap. I only have 50K on mine. I think I will keep a few quarts of oil in the trunk, so I always have some oil handy. Thanks for the info.
 
#16 ·
Bass master, staying in 3rd gear as you suggest is a good idea, thanks, I will try it. I found another use for using 3rd gear, when cruising on the highway and then taking another road like our entrance to our airport, I slowed down, then I noticed the car wants to keep rolling at its previous speed, while I was looking for my quickly approaching turn off, so 3rd gear makes it easier to control the speed also.
 
#23 ·
If there is a slight grade like our airport entrance, the first time I had been there in years, before all of the 9-11 security, where you quickly need to figure what lane you need to get to various areas, I found that my Impala would roll right back up to 50+ MPH after I had slowed down to 30 MPH, (with no one behind me) and I never had to ride the brakes with any other car under a similar situation. I had just bought my LTZ, and it quickly taught me a lesson, I will remember. Third gear solves that problem too. Being in 3 cylinder mode might have something to do with how easily it keeps its speed up on a slight down grade? (I could do without AFM) If it wasn't necessary to pull the engine to change the cam, I would consider installing the kit myself, depending on what it costs, of course.
 
#24 ·
Ah, I missed the .6vs.9 lol.

the wifes denali has it over time it kills the valve train, and they are made of gold, like $900 ish for the 4 that shut down vs $29.99 for stock or something like that.. Most people just delete it after warranty and swap the valve spings and stuff.
 
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