Anyting I can do to prevent AFM issues?

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Roger08LTZ

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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.
I sent my PCM to LT1Swap.com for the AFM disable. While I assume they know what they are doing and will do the job correctly. How do I know if the truck is activating AFM Mode?
 

89Suburban

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I sent my PCM to LT1Swap.com for the AFM disable. While I assume they know what they are doing and will do the job correctly. How do I know if the truck is activating AFM Mode?


Seat of the pants feel or look in your DIC display.
 

iamdub

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I sent my PCM to LT1Swap.com for the AFM disable. While I assume they know what they are doing and will do the job correctly. How do I know if the truck is activating AFM Mode?

Press the top DIC button until you get to the screen that displays "INST MPG and "V4/V8 MODE".

I don't think you'll have anything to worry about. Disabling AFM in the tune is one of their main services.
 
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Roger08LTZ

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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 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.
That's it for sure, this rocker is right under the vent hole for the PCV, so I pretty sure this rocker is black.
 

BG1988

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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!
the lifter tick is nothing to be worried about unless your gas engine sounds like a diesel engine...
I'm in many different(everyday) cars, trucks and SUV's lots of them have lifter ticks (some you can hear all the lifters ticking) even the older 800 series engines(have it) DaimlerChrysler products, brand new cars, older etc... the quietest was a newer tahoe almost accidentally cranked the engine while it was running... good thing i checked the tachometer...


my oil consumption is from a leak at the rear(from the VLOM seal) GM is actually to blame for this because of tooling issues at the factory when the engines were built.. 109k miles.. i have not lost any oil with the Pennzoil i switched to, 1500 miles in this oil change. at lest nothing visible on the ground.. i plan to change the oil next Monday on my day off.... i know every 1500 miles is excessive, but oil is cheap and the engine is expensive...i did check the oil and it does not "smell of gas" I think fuel contamination might be getting in the oil (because of fuel trim issues i'm dealing with at the moment) as it smelled like gas the last time i changed it..(so just changing more often just in case )

the engine oil stays spotless & clean tell about 4500 miles then stuff is floating around just a few specs of carbon... i have been doing 3k OCI
 

iamdub

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That's it for sure, this rocker is right under the vent hole for the PCV, so I pretty sure this rocker is black.

This is why they updated the baffle design. That rocker flicks drops of oil directly into the PCV baffle where its supposed to just be oily vapor. The baffle floods and liquid oil gets sucked into the PCV stream, dumped into the rear of the intake manifold and, ultimately, inhaled by the rearmost cylinders, particularly #7.

Driving easy with no hard throttle or high RPM reduces these effects.
 
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Roger08LTZ

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I got my PCM back from getting the AFM disable done and I've driven it a few days now and no V4 indicated. I don't feel any power difference, but I didn't expect any. I'd highly recommend https://lt1swap.com/afm_delete.htm for AFM disable. Very fast turnaround. Absolutely no side effects or down side as far as I can tell. I feel much better that I won't get a lifter stuck collapsed now. You know they are creating these systems like AFM, DOD or MDS systems to make the EPA requirements, but how many cars have been junked early due to these systems killing a perfectly good engine. That's not good for the environment or the consumer.
 
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Geotrash

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I got my PCM back from getting the AFM disable done and I've driven it a few days now and no V4 indicated. I don't feel any power difference, but I didn't expect any. I'd highly recommend https://lt1swap.com/afm_delete.htm for AFM disable. Very fast turnaround. Absolutely no side effects or down side as far as I can tell. I feel much better that I won't get a lifter stuck collapsed now. You know they are creating these systems like AFM, DOD or MDS systems to make the EPA requirements, but how many cars have been junked early due to these systems killing a perfectly good engine. That's not good for the environment or the consumer.
That's a significant problem with the way many (but not all) regulations are written. They optimize for one parameter without considering the whole picture.
 

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