Anyting I can do to prevent AFM issues?

[Roger08LTZ]

My 2008 Tahoe 5.3 is running fine now, but i've been reading up on all of the AFM issues. I see the Range Technology AFM Disabler. Most people seem to be buying them for performance or exhaust note reasons, but I was woundering if using this or some other method to disable AFM will make the lifters last longer? My thought is if the lifters don't collapse they can't get stuck. Assuming I don't really care about sound or power, will a AFM disabler really help avoid the issue? Worth doing? My car has 190K on it, if it's lasted this long, perhaps I have good lifters and shoulden't bother?


Thanks!

 

[OR VietVet]

Best thing I found to avoid the dreaded AFM problem is............buy a NBS 2000 to 2006 rig.

 

[iamdub]

My 2008 Tahoe 5.3 is running fine now, but i've been reading up on all of the AFM issues. I see the Range Technology AFM Disabler. Most people seem to be buying them for performance or exhaust note reasons, but I was woundering if using this or some other method to disable AFM will make the lifters last longer? My thought is if the lifters don't collapse they can't get stuck. Assuming I don't really care about sound or power, will a AFM disabler really help avoid the issue? Worth doing? My car has 190K on it, if it's lasted this long, perhaps I have good lifters and shoulden't bother?


Thanks!

At 190K, your clock is ticking. Keeping the system disengaged (lifters locked) certainly seems to be the second best option next to a mechanical deletion of the system. Have you owned your '08 for all 190K miles or at least know its maintenance and repair history? An '08 would have the oldest rendition of the AFM components unless it has been upgraded, which is usually done following a failure. Upgrades were made to the lifters and VLOM and a couple other parts were revised during this generation starting in 2010-2011. Regardless, the fuel savings will never outweigh the risk of keeping AFM active.

Instead of a plug-in device, I'd strongly recommend having AFM tuned out. You can have this done for as little as $50 plus cost of shipping your PCM (~$15?). You'll just have to remove you PCM and have your Tahoe out of commission for a few days. IMO, still a far better option than $200+ for a plug-in module that will still require tending to. For $65, you can "set it and forget it". And if you ever have a mechanical failure and need to do a delete, the PCM won't require any programming- swap the parts and get back on the road.

Go here: https://lt1swap.com/afm_delete.htm

Also, do you monitor your oil level? AFM contributes to oil consumption but there's also an upgraded driver side valve cover that really helps, too. This is another item introduced around 2010 that yours should get if it hasn't gotten it already.

Speaking of oil levels, a huge killer of the AFM system is dirty oil due to improper maintenance. The system is sensitive to sludge. Yours lasting so long tells me you keep up clean oil in it or are just lucky. AFM disabled or not, stay on top of your oil changes.

 

[Roger08LTZ]

Well I've only had this car a little over 1 year and I have no idea on prior maintenance except that it's in really nice shape which indicates overall care, but no guarentee good oil change maintenance. Many people care for the car, but push oil changes. Oil Consumption is zero or close to it, so that's a good sign. I very much like the reprogramming option! I actually do have a spare PCM due to a mis-diagnosis discussed on another thread, so I might not even be offline. This brings another question When I swepped in the "New" PCM the car started, but had the same issue I was chasing, plus a bunch more. I did'nt record all of the codes, but one was something like Crank sensor relearn, others related to comunication to other modules. As I was not in the mood to start chasing new problems, I swapped back to my stock PCM and found the real issue (a bad ground of course!). Anyway, Any idea what's involved in getting a new PCM to be happy in it's new home? I do plan to swap it back sometime and attempt to solve this lssue just so I know I have a good PCM in reserve since I bought it already.

Thanks!

 

[iamdub]

Well I've only had this car a little over 1 year and I have no idea on prior maintenance except that it's in really nice shape which indicates overall care, but no guarentee good oil change maintenance. Many people care for the car, but push oil changes. Oil Consumption is zero or close to it, so that's a good sign. I very much like the reprogramming option! I actually do have a spare PCM due to a mis-diagnosis discussed on another thread, so I might not even be offline. This brings another question When I swepped in the "New" PCM the car started, but had the same issue I was chasing, plus a bunch more. I did'nt record all of the codes, but one was something like Crank sensor relearn, others related to comunication to other modules. As I was not in the mood to start chasing new problems, I swapped back to my stock PCM and found the real issue (a bad ground of course!). Anyway, Any idea what's involved in getting a new PCM to be happy in it's new home? I do plan to swap it back sometime and attempt to solve this lssue just so I know I have a good PCM in reserve since I bought it already.

Thanks!

From where did you get the replacement PCM? From a salvage yard? First, it needs to be a match to your vehicle and it will need programming. It might have been from a different year and/or model with different powertrain options. A crank sensor relearn is always needed any time a CKP sensor is replaced or the PCM is replaced. You might have to have that PCM programmed and operational before sending it to LT1Swap because I don't think they can do anything for that. Or, if they can, it might just be a few bucks more. I don't know their resources but I'd bank on having it done locally and sending it out after you confirm it works, if you must avoid decommissioning your Tahoe for a few days.

If you wanna learn more of the health of your engine, pop off that driver side valve cover. It's about a 30-minute job moving casually and using basic hand tools. You'll be able to see if it has been updated as well as see the internals of the engine to gauge the previous maintenance and if/how you should proceed with future maintenance.

 

[Roger08LTZ]

From where did you get the replacement PCM? From a salvage yard? First, it needs to be a match to your vehicle and it will need programming. It might have been from a different year and/or model with different powertrain options. A crank sensor relearn is always needed any time a CKP sensor is replaced or the PCM is replaced. You might have to have that PCM programmed and operational before sending it to LT1Swap because I don't think they can do anything for that. Or, if they can, it might just be a few bucks more. I don't know their resources but I'd bank on having it done locally and sending it out after you confirm it works, if you must avoid decommissioning your Tahoe for a few days.

If you wanna learn more of the health of your engine, pop off that driver side valve cover. It's about a 30-minute job moving casually and using basic hand tools. You'll be able to see if it has been updated as well as see the internals of the engine to gauge the previous maintenance and if/how you should proceed with future maintenance.

I got the PCM from Flagship One https://www.fs1inc.com/ they programmed the VIN into it and the factory key worked and it started and ran. I have not attempted to contact them for support as this was not my real issue, but I will. I'll definately pull that valve cover and post some pics.

Thanks

 

[iamdub]

I got the PCM from Flagship One https://www.fs1inc.com/ they programmed the VIN into it and the factory key worked and it started and ran. I have not attempted to contact them for support as this was not my real issue, but I will. I'll definately pull that valve cover and post some pics.

Thanks

Cool! Then the problems it had might have just been needing the CKP relearn and fixing the actual/original problem, which was that ground. A shop or someone with a Tech2 or capable bi-directional scan tool can perform the relearn in about a minute. Supposedly, you can get it to relearn by performing a very specific drive cycle. But, it'll likely not happen unless you can travel for miles at a particular speed with no stops or other traffic around for the duration. I'd do it the standard way. If it works, leave it in and send off your original or vice-versa. Then send off the other so you won't have to worry about AFM being abruptly taken out of deep hibernation if you ever need to swap in that PCM.

 

[Roger08LTZ]

I recently purchased an Xtool D8 scanner which seems to have the crank sensor learn feature. I'm new to scan tools other than code readers, so it's a learning experience.

 

[iamdub]

I recently purchased an Xtool D8 scanner which seems to have the crank sensor learn feature. I'm new to scan tools other than code readers, so it's a learning experience.

Aw, hell! You're set up! What're you waiting for? Let's see if that new PCM is good to go!

 

[Roger08LTZ]

The new PCM is in and I did the Crank relearn, no problem. No other errors.

I also took off the valve cover. It looks good especially for 190+K miles

 

[swathdiver]

Looks good and that is the old valve cover, not the new and improved one which is 12570427 for 2007-2008.

Keep the oil clean. Take a picture of the underside of the intake where the VLOM is, maybe we can tell if you have the new one or the old one.

 

[Roger08LTZ]

What's the new and improved valve cover do? Seems to me as long as it's keeping the oil inside the engine, it's good.

Here is a shot of my valley. It sure looks original.

 

[swathdiver]

What's the new and improved valve cover do? Seems to me as long as it's keeping the oil inside the engine, it's good.

Here is a shot of my valley. It sure looks original.

It helps to reduce oil consumption. If you're not consuming oil, don't bother.

That is the new VLOM. It was introduced in 2011. My motor got a new one in 2016 at about 100K miles and AFM was turned off in the tune 18K miles afterwards.

Most AFM failures occur because the VLOM solenoids get out of time, usually because of dirty oil, which causes the lifters to jam and fail and maybe bend a pushrod or more as well.

 

[Roger08LTZ]

It helps to reduce oil consumption. If you're not consuming oil, don't bother.

That is the new VLOM. It was introduced in 2011. My motor got a new one in 2016 at about 100K miles and AFM was turned off in the tune 18K miles afterwards.

Most AFM failures occur because the VLOM solenoids get out of time, usually because of dirty oil, which causes the lifters to jam and fail and maybe bend a pushrod or more as well.

Two questions, as shown on one of the pictures one of my rockers looks black. Anything to worry about? The other thing I've been told these LS type engines have needle bearings in the rockers that are prone to failure and that it's common to convert to a bushing instead. Is that something relevant to the 5.3 or just the real LS engines like the LS1 etc.?

Thanks!

 

[iamdub]

The new PCM is in and I did the Crank relearn, no problem. No other errors.

I also took off the valve cover. It looks good especially for 190+K miles

View attachment 381161View attachment 381162View attachment 381163View attachment 381164

Awesome! Yeah, it looks pretty good in there, especially for the mileage.

Two questions, as shown on one of the pictures one of my rockers looks black. Anything to worry about? The other thing I've been told these LS type engines have needle bearings in the rockers that are prone to failure and that it's common to convert to a bushing instead. Is that something relevant to the 5.3 or just the real LS engines like the LS1 etc.?

Thanks!

I'm wondering if that rocker is in line with the hole in the PCV baffle and it's just from years of oil dripping back onto it and cooling when parked. It's great that you don't have any or much oil consumption, but I'd still get that updated cover.

I wouldn't say the stock rocker bearings are "prone to failure". At least, not in a stock setup. They're the same rocker design used across all LS engines including the high-performance car variants spinning 7,000 RPM and with more cam action happening. To me, the reports of their failure has become more of a Hegelian dialectic. I'd trust the stock ones over the bushing style. I researched stock and aftermarket needle bearings versus the various bushing styles to exhaustion a few months ago. My TSP cam is decently comparable to a stock LS6 cam and I have the "heavier duty" LS6 valve springs and my redline is about 600 RPM less than that of the LS6. I decided that if stock rockers do fine in an LS6, they'd be fine in my warmed over LMG. Problems arise with stock bearings (and still with the aftermarket bushings) on more heavily modded engines with big cams, high spring pressures, higher RPM, etc. I did my engine refresh at 200K and put the original rockers back in with the intent to swap them later once I had settled on some aftermarket ones. They did just fine with all the "abuse" following the refresh with upgrades, but I wanted the peace of mind of at least having something new. Back in May, I bought 16 new GM OEM rockers off eBay for $9.99 each and haven't given it a second thought. If I were to go aftermarket, these are what I'd get: http://www.ws6project.com/user_stor...cts_id=9356&osCsid=med8ej8uujfipsmotus6cus9s1

 

[Geotrash]

+1 on the stock rockers being good to go. The reports of failures were from very early LS engines and I've seen zero reported failures in the last 15 years in any of the forums. I researched before I did my cam swap. I did end up going with the Brian Tooley Trunnion upgrade kit but if I had it to do over again, I wouldn't bother. I would worry more about the valve springs.

 

[Roger08LTZ]

Awesome! Yeah, it looks pretty good in there, especially for the mileage.




I'm wondering if that rocker is in line with the hole in the PCV baffle and it's just from years of oil dripping back onto it and cooling when parked. It's great that you don't have any or much oil consumption, but I'd still get that updated cover.

I wouldn't say the stock rocker bearings are "prone to failure". At least, not in a stock setup. They're the same rocker design used across all LS engines including the high-performance car variants spinning 7,000 RPM and with more cam action happening. To me, the reports of their failure has become more of a Hegelian dialectic. I'd trust the stock ones over the bushing style. I researched stock and aftermarket needle bearings versus the various bushing styles to exhaustion a few months ago. My TSP cam is decently comparable to a stock LS6 cam and I have the "heavier duty" LS6 valve springs and my redline is about 600 RPM less than that of the LS6. I decided that if stock rockers do fine in an LS6, they'd be fine in my warmed over LMG. Problems arise with stock bearings (and still with the aftermarket bushings) on more heavily modded engines with big cams, high spring pressures, higher RPM, etc. I did my engine refresh at 200K and put the original rockers back in with the intent to swap them later once I had settled on some aftermarket ones. They did just fine with all the "abuse" following the refresh with upgrades, but I wanted the peace of mind of at least having something new. Back in May, I bought 16 new GM OEM rockers off eBay for $9.99 each and haven't given it a second thought. If I were to go aftermarket, these are what I'd get: http://www.ws6project.com/user_stor...cts_id=9356&osCsid=med8ej8uujfipsmotus6cus9s1

I'm going to leave the rockers alone. The people telling me this are track racers with tube chassis dedicated race cars running LS3's. They might be pushing their motors a tad bit harder than my wife and I are in the Tahoe.

 

[Foggy]

The OE rockers fail mostly due to high lift camshafts...
They can only rotate a limited amount of degrees... So with stock lift numbers,
generally under .540 ish, there is no reason to change.. But once you get more lift
and of course then you need more spring pressure, they can fail.
I did the bushing upgrade on mine since my new cam is .560 ish lift and for
cheap insurance against a breakdown.

 

[swathdiver]

Two questions, as shown on one of the pictures one of my rockers looks black. Anything to worry about?

I did see that and thought to myself that if it had gotten hot, it would be kinda blue. A lot of these motors had AFM failures by around 100K and if caught early were easily repaired with the latest parts with no damage to the engines.

When these engines first came out, the Avalanche guys were tweaking the computers to get even better gas mileage out of them, up to 26 mpgs on four cylinders if memory serves.

 

[fozzi58]

these engines first came out, the Avalanche guys were tweaking the computers to get even better gas mileage out of them, up to 26

That was me. Had an '08 Avy with 160k+ on the clock when I sold it. I had a hand held tuner that I set engine management to economy. Was easily getting 30+ mpg on highway. Bought the truck in 2008 used with 8500 miles on it (basically new), and had it until I bought my 17 burb. I did oil changes early and often. I think I went 5000 miles on the oil once in all the years I owned it, otherwise oil change every 3k miles. Never had a lifter failure. She ran perfect the whole time I owned her. Wish I could say the same for the transmission!