the money is my thing too.. I'm not. building a 1000hp racing engine. it's just gotta live a while around town between idle and like 2500 rpm. and this Gen of trucks are listed for about 2500$ on face book around here. yeah they are a bit more beat down than mine, but eh. I have zero desire to fix anything that isn't broken and with almost all new parts, even from the dealership parts department being suspect at best, or down right bad out of the box. the days of me replacing things because it's the right thing to do ate long long gone.
AFM/DoD Delete Advice Needed
- Thread starter Kwing
- Start date
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the money is my thing too.. I'm not. building a 1000hp racing engine. it's just gotta live a while around town between idle and like 2500 rpm. and this Gen of trucks are listed for about 2500$ on face book around here. yeah they are a bit more beat down than mine, but eh. I have zero desire to fix anything that isn't broken and with almost all new parts, even from the dealership parts department being suspect at best, or down right bad out of the box. the days of me replacing things because it's the right thing to do ate long long gone.
330,000 plus miles, don't think I'd invest the money in an AFM delete.
But that is a bit subjective. Now if the chassis looks pristine, and the transmission is fairly recent..... I'd probably look at rebuilding it, doing the AFM delete on the way.
Most likely the vehicle is in effect totaled..... The repair costs exceed the value. But that doesn't mean don't do it. Just depends how attached to it you are. It has lived a good long life.... And yes, sometimes people put the money into a vehicle with that many miles for sentimental reasons.
But strictly on age measured in miles, especially if the rest of the drivetrain is in need of attention.... It might make the best financial sense to retire it.
But that is a bit subjective. Now if the chassis looks pristine, and the transmission is fairly recent..... I'd probably look at rebuilding it, doing the AFM delete on the way.
Most likely the vehicle is in effect totaled..... The repair costs exceed the value. But that doesn't mean don't do it. Just depends how attached to it you are. It has lived a good long life.... And yes, sometimes people put the money into a vehicle with that many miles for sentimental reasons.
But strictly on age measured in miles, especially if the rest of the drivetrain is in need of attention.... It might make the best financial sense to retire it.
Explained in terms of "what" to do, but without any "why". "Why" matters.
Does the AFM cam have different lift? Different duration? Different ramp? Different separation angle? Different centerlines?
And whatever is different, how different is it? Enough to really matter?
Based on RET423's "hashing", which is one of the first ones I've seen that had more than "because I said so", whatever the differences are weren't enough for an otherwise seemingly knowledgeable individual to notice any difference in performance or smoothness. But for every story like RET423's, there is one saying "it didn't work".
Cars/engines are not black magic. They are engineering. "You have to replace the cam" is an opinion. "You have to replace the cam because the AFM cam has X, Y, and Z that differ from the non-AFM cam" is a statement of engineering fact - at least as factual as the teller knows it to be.
I have to get my crippled @$$ under that hood, standing on my half-bionic heel, bending over with my 3 herniated discs putting pressure on my umbilical hernia, inflaming my carpal tunnel, all in 110+ degree Phoenix heat, and at the end of the day when I explain to my daughter why I can't buy her new clothes and shoes, while I'm crying on the couch from the pain I've endured, I'd like to know that the justification for all of it was more than "because I said so", LOL.
Marky Dissod
Full Access Member
The conversations SAY a lot, they just don't conclude anything.
There are people who have NOT gotten cancer or emphysema or COPD from smoking a pack (or more) a day,
but cigarettes are still carcinogens - they, among other things, increase the odds of getting cancer.
By the same token, some people have not disabled Engine Half@$$, and suffered no consequences. Yay, congratulations to those people,
doesn't change the fact that V4-mode-able V8s are more likely to suffer valvetrain issues (among other issues) vs simpler V8s.
I'm (probably) the ONLY person who had a '12 Yukon XL tuned to do EVEN MORE Engine Half@$$ EVEN MORE OFTEN, and suffered no valvetrain issues
(suffered other issues though) - but I witnessed about a hundred NYC uber/lyft/gett/juno/via drivers of Suburbans/XLs/ESVs with valvetrain issues.
Disabling V4 mode betters the odds. Changing oil sooner than the Oil Life Monitor suggests (in terms of percentage) betters the odds.
Converting the engine to a full time V8 with commensurate hardware DRASTICALLY betters the odds.
All that said, I get why some people can't or don't do a full Engine Half@$$ delete - I likely would NOT've been able to afford one.
Should've disabled Engine Half@$$ instead of what I did.
I call it the poor-man-tax.
See, from a 10,000 ft level overview with an emergency financial cushion, a retirement account, maybe some stocks, a credit card with a couple grand in it for emergencies... yeah, the obvious answer is "do it right or just replace it".
When you're paycheck-to-paycheck with a credit score so bad even $300 secured credit cards have 50/50 approval odds, then blowing $500 every 6-12 months to half@$$ it until the next shoe drops isn't only more "logical", it's really the only option available. Something that is far too easy for those not living it to laugh at and shrug it off.
The problem is, I'm getting too old for this crap, LOL. A 12-hour saturday isn't an inconvience any more, it's an ordeal requiring weeks of recovery, assuming i can even make it to the finish line without having to take a week to recover in the middle.
But I digress...
I just wanna know if I need to replace the cam! ROTFL
Marky Dissod
Full Access Member
I save SO much more @ CostCo, even though I had to change my outlook from a day or two ahead, to a month or even a season ahead in some cases.
It's a case of 'how much (more) money are you (comfort)able spending to improve the odds that nothing will go wrong?'
Were I you, I'd replace the cam with a different GM OE cam, if only 'cause you said this is the 2nd time the same lifter went bad.
Also, since you can't really look at the cam without pulling out (heh), might as well pull it out and replace it, don't chance reusing it AGAIN.
You don't NEED to, it's just a really good idea.
It's a case of 'how much (more) money are you (comfort)able spending to improve the odds that nothing will go wrong?'
Were I you, I'd replace the cam with a different GM OE cam, if only 'cause you said this is the 2nd time the same lifter went bad.
Also, since you can't really look at the cam without pulling out (heh), might as well pull it out and replace it, don't chance reusing it AGAIN.
have you heard of a top side creeper? that might help with the physical side of it. I don't work on mine without bringing one home from work.
so I might have missed it, but did to do a lifter release and the oil block off a while ago and now it's back stuck again won't release and is tapping. if so, that makes me a bit worried that it's not just stuck again but lifter went bad, from roller or tray and ate the cam. so this might all be for nothing.
so if I was going full cheap.. pull the heads, drop in ls7 lifter and new trays from Michigan Motorsports as they seem to sell oem ones. put heads back on, make sure you measure the push rods on the afm and no afm ones. order the correct size to get the reload right, as that might be what most are skipping.. button up and see what happens? you've already got the oil block off under the oil pressure sensor installed and afm turned off in the tune, not just a plug in dongle. so at that point money on a smooth vlom is wasted but pretty cheap. pound the bearings in the tower if you must, cheap but I seem to be the only one that sees no point in that. I have a 110k mile ls3 car, it has the same towers, not blocked off from the factory and non afm lifters. gm did it, it seems fine.
if you do find after that that it doesn't work. the cam swaps out of the front of the motor without removing the heads again. do the wooden dowls thru the front of the block to hold the lifters up as you pull the cam out trick.
over all same amount of work, just split up in 2 parts, and you can spread the money spent on parts out to the next check too?
I don't know.. feels like what I'd try. especially with my hybrid truck, since there's no non afm cam available for mine.(weird Miller cycle cam timing only used in the hybrid ones) was always thinking I'd have to bite the bullet and put new oem afm lifters in it and just not use them again if they go bad.
so I might have missed it, but did to do a lifter release and the oil block off a while ago and now it's back stuck again won't release and is tapping. if so, that makes me a bit worried that it's not just stuck again but lifter went bad, from roller or tray and ate the cam. so this might all be for nothing.
so if I was going full cheap.. pull the heads, drop in ls7 lifter and new trays from Michigan Motorsports as they seem to sell oem ones. put heads back on, make sure you measure the push rods on the afm and no afm ones. order the correct size to get the reload right, as that might be what most are skipping.. button up and see what happens? you've already got the oil block off under the oil pressure sensor installed and afm turned off in the tune, not just a plug in dongle. so at that point money on a smooth vlom is wasted but pretty cheap. pound the bearings in the tower if you must, cheap but I seem to be the only one that sees no point in that. I have a 110k mile ls3 car, it has the same towers, not blocked off from the factory and non afm lifters. gm did it, it seems fine.
if you do find after that that it doesn't work. the cam swaps out of the front of the motor without removing the heads again. do the wooden dowls thru the front of the block to hold the lifters up as you pull the cam out trick.
over all same amount of work, just split up in 2 parts, and you can spread the money spent on parts out to the next check too?
I don't know.. feels like what I'd try. especially with my hybrid truck, since there's no non afm cam available for mine.(weird Miller cycle cam timing only used in the hybrid ones) was always thinking I'd have to bite the bullet and put new oem afm lifters in it and just not use them again if they go bad.
I DID do the lifter release (twice) and oil block, along with busting out the vlom seals to ensure there was no way the AFM lifters could pressurize again. Unfortunately by the time I did that, it was in response to #6 collapsing (ie too late).
Had I known about the inner workings of the system back when I did the long block the first time the AFM failed, I would have done the oil block and vlom seals on the new engine and wouldn't be right back in the same position, but I'z'a too shtoopid for that, LOL.
The whole thing about you comment (and @Marky's) about the cam needing to replaced due to collateral damage is really the crux of my original post.
If the cam is actually different, and meaningfully so, it's an open and shut case: I have to swap it.
If it's just a protective measure because of potential wear or damage, it becaomes a different equation.
This cam only has 130k on it, and the failure of the lifter was gradual, over time, as the vlom pressurized via bleed through. The AFM was disabled, first by dongle, then by HP Tuner, from the moment the new engine went in.
That makes the wear/damage risk much lower, to the point that the risk/reward balance isn't so tipped in the cam's direction...
I have seen those side creepers, but at 250+lbs, the ones that feel safe enough for my fat @$$ are scary expensive, LOL
The "why" behind the AFM delete components:
1. The pre AFM engines were extremely reliable. The AFM components destroyed that.
2. The cam, and half the lifters, oil pump, valley cover are what was changed, as well as adding an oil pressure relief valve in the oil pan, and the solenoids in the valley cover....and software to control this aberration. Remove and replace these components with the original design....you have a damn good engine.
3. Problem is: A failure of any of these components, often destroys the entire engine. So only addressing half the parts doesn't really improve reliability.
Budget is always a consideration. This can be an expensive issue to fix properly. These are not vehicles to own on a tight budget.
4. Prevention. Budget tight, and running ok? At least grab yourself an OBD2 plug-in to disable the components. Disregard the oil change interval on the dash, and do it every 3500-4500 miles. (Which may be the biggest contributor to failures.... extended intervals by following the oil life monitor)
The evidence on AFM is indisputable. Take a look at how many pre-2006 LS 6.0 engines are still going strong well past 300k miles, no oil consumption, no common lifter failures....and none of the AFM hardware.
Variable Valve Timing needs to be mentioned. I like it, provides low end torque and gives much better fuel mileage. ...BUT...it requires oil pressure provided through the #2 cam bearing, reducing the width of the bearing surface significantly. I often see this bearing failing around 170-240,000 miles. That would be deemed 'reliable' by most engineers, especially considering the fuel savings over that time should more than exceed the cost of an engine rebuild. I'm okay with that as I do my own work. But, look at a non AFM engine with no VVT, common to have the cam bearings still looking good at 400k+ miles
It's not just GM...every manufacturer has overcomplicated reliable engine designs to aim for better mileage and emissions....all at the expense of reliability.
1. The pre AFM engines were extremely reliable. The AFM components destroyed that.
2. The cam, and half the lifters, oil pump, valley cover are what was changed, as well as adding an oil pressure relief valve in the oil pan, and the solenoids in the valley cover....and software to control this aberration. Remove and replace these components with the original design....you have a damn good engine.
3. Problem is: A failure of any of these components, often destroys the entire engine. So only addressing half the parts doesn't really improve reliability.
Budget is always a consideration. This can be an expensive issue to fix properly. These are not vehicles to own on a tight budget.
4. Prevention. Budget tight, and running ok? At least grab yourself an OBD2 plug-in to disable the components. Disregard the oil change interval on the dash, and do it every 3500-4500 miles. (Which may be the biggest contributor to failures.... extended intervals by following the oil life monitor)
The evidence on AFM is indisputable. Take a look at how many pre-2006 LS 6.0 engines are still going strong well past 300k miles, no oil consumption, no common lifter failures....and none of the AFM hardware.
Variable Valve Timing needs to be mentioned. I like it, provides low end torque and gives much better fuel mileage. ...BUT...it requires oil pressure provided through the #2 cam bearing, reducing the width of the bearing surface significantly. I often see this bearing failing around 170-240,000 miles. That would be deemed 'reliable' by most engineers, especially considering the fuel savings over that time should more than exceed the cost of an engine rebuild. I'm okay with that as I do my own work. But, look at a non AFM engine with no VVT, common to have the cam bearings still looking good at 400k+ miles
It's not just GM...every manufacturer has overcomplicated reliable engine designs to aim for better mileage and emissions....all at the expense of reliability.
Point #1 is why we're having this conversation, because I'm pretty sure that is now a universally accepted fact, like how horrible of an idea it was for the Northstar to have a split crankcase (funny how the two's origins are shared, but not that I'm biased against whatever team of jack@$$es was in charge of decision making at Cadillace in the late 80's, LOL).
The focus here, though, is the cam in your list in #2. WHAT changed between the non-AFM cam and the AFM cam?
That WHAT drives the WHY behind changing the cam - which equates to several more hours of work, a huge increase in collateral damage risks tearing apart 20 year old systems made from poorly spec'd materials, not to mention the instant 2x bump in parts costs for another set of seals and parts not otherwise needed...
AFM cam has a different profile. (Only on the AFM cylinders) Not suitable to use a standard lifter on the AFM lobes.
Here's the basics on the difference between the L94 AFM cam, and the non-AFM version, the L92. Differences in lift, duration. AFM lobes have a different 'slope' to them....keep the AFM cam, and things will be sort of off balance on 4 cylinders. (Only the afm lobes are different from the normal cylinders, as they are designed for different lifters.) You'll lose duration and exhaust valve lift as well. Keep in mind the AFM software is designed to adjust for this out of balance valve system.....you disable it, and the ecm is looking for a normal cam profile, where all 16 lobes are the same...and you won't have that with an AFM cam.
Specifications Comparison
Here's the basics on the difference between the L94 AFM cam, and the non-AFM version, the L92. Differences in lift, duration. AFM lobes have a different 'slope' to them....keep the AFM cam, and things will be sort of off balance on 4 cylinders. (Only the afm lobes are different from the normal cylinders, as they are designed for different lifters.) You'll lose duration and exhaust valve lift as well. Keep in mind the AFM software is designed to adjust for this out of balance valve system.....you disable it, and the ecm is looking for a normal cam profile, where all 16 lobes are the same...and you won't have that with an AFM cam.
Specifications Comparison
- L94 Camshaft (Part #12623066):
- Duration @ .050 in. (Intake / Exhaust): 195° / 201°
- Valve Lift (Intake / Exhaust): 0.500 in. / 0.492 in.
- Lobe Separation Angle (LSA): 115°
- AFM Capability: Yes (features special lobes for AFM lifters on specific cylinders)
- VVT Capability: Yes (4-pole 4X phaser attachment, 1-bolt)
- L92 Camshaft (Part #12612273):
- Duration @ .050 in. (Intake / Exhaust): 198° / 209°
- Valve Lift (Intake / Exhaust): 0.500 in. / 0.500 in.
- Lobe Separation Angle (LSA): 115°
- AFM Capability: No
- VVT Capability: Yes (4-pole 4X phaser attachment, 1-bolt)
- L94 Camshaft (Part #12623066):
West 1
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Many on this forum loudly spout off that we should install an AFM delete on all of these that run AFM?
When you delete the AFM the engine runs on all 8 cylinders full time?
The AFM cam runs perfectly with AFM deleted. Good power, good mpg exactly as a non AFM cam performs.
I learned later after this post that the AFM lobes are a little different on the cam for the special AFM lifters so they do not work well with the stock Non AFM lifters. Learned something new today.
When you delete the AFM the engine runs on all 8 cylinders full time?
The AFM cam runs perfectly with AFM deleted. Good power, good mpg exactly as a non AFM cam performs.
I learned later after this post that the AFM lobes are a little different on the cam for the special AFM lifters so they do not work well with the stock Non AFM lifters. Learned something new today.
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The cams are different, just measure. (The afm lobes are the main difference, besides the exhaust lift and overall duration.) It will run, slightly off balance....but eventually that takes its' toll on any engine. Some will fail quick, some last a bit, depending on how they are driven I suspect. (High rpms )
If you find yourself with some time, you should read up on the Ladder of Inference, but I'll skip the philosophical gap of us being on two separate levels on the ladder in this disagreement, and instead jump right to the point...
We are talking about a 2007 5.3L FFV AFM, which appears to be an LM7, from what I can find. The waters get muddy trying to figure out what the non-AFM counterpart is for the LM7 though.
Your provided cam specs, which credit to you are the first I've seen provided on the subject, are for the L94 with a L92 counterpart... Which upon searching appear to both be 6.2L motors with VVT.
We are not talking about the same engines...
But you may be getting me onto the correct track here.
Can anyone tell me the non-AFM counterpart to the LM7? Assuming of course mine is the LM7, LOL.
Marky Dissod
Full Access Member
You can't have an LM7 if your engine has Engine Half@$$. LM7/L59/LM4/L33 are previous versions of the 5.3L you're concerned with.
What's your VIN's 8th character? Settle it that way.
LM7s are full time V8s. If your engine can Half@$$, it's not an LM7/L59/LM4/L33. H2O was already filtered for ya:
Just to be sure, the cam you want from a 5.3L will be an LH8 / LH9 / LMF - actually, if your engine LACKS Variable Cam Timing,
you COULD use an earlier 5.3L cam if you wanted?
It'd be cool if there were a 'better' GM OE cam, but I don't know what that'd be? Maybe someone else here does?
See, this is why I'm here asking PEOPLE who KNOW things! LOL
I tell ya, Google has been absolutely ruined by AI!
Google claimed the '07 5.3 FFV AFM was the LM7, ChatGPT claims it's the LMG, with it's non-AFM counterpart being the LY5, but Google claims the LY5 is an AFM motor.
How the bleeping bleep is anyone supposed to find facts in 2026, for eff's sake?!?
Regardless...
8th digit from the left or right? 8th from the left is 0 (zero), 8th from the right is 7.
Marky Dissod
Full Access Member
Please be more careful with conjectures, people ... disabling is NOT the same as deleting ... etc ...
If you haven't changed the cam specs in the tune, the ecm still thinks it has the same Half@$$-able cam, it just never Half@$$es it again.
HOWEVER, it is true that the cam lobes for the 4 part time cylinders are SLIGHTLY different from the other 4 lobes for the full time cylinders.
Over a long enough period of time, this V8 will eventually become two similar yet slightly different V4s sharing a common crank,
which would likely lead to asymmetrical bearing wear on a long enough timeline.
Volumetric Efficiency tables for Half@$$-able cams, are SLIGHTLY different from VE tables for full time V8 cams.
Misfire detection tables for Half@$$-able cams, are SLIGHTLY different from VE tables for full time V8 cams.
There are other differences that don't come to mind right now.
*Disabling Engine Half@$$ just turns off that feature-bug, no cam specs are being changed because the same cam is still in use.
*If you DELETE Engine Half@$$, but for some strange reason, you keep the Half@$$ cam, then your tuner leaves those parts of the tune alone,
and you keep driving around with a pair of 2.7L V4s sharing a crank and a block.
*Most people delete Engine Half@$$ more thoroughly, with a Full@$$ V8 cam, which requires changing those things in the tune.
If you JUST ... ONLY disable Engine Half@$$ with a plug-in, or a tune that MERELY disables V4 mode, you only told the ecm to avoid using that feature, ever.
If you haven't changed the cam specs in the tune, the ecm still thinks it has the same Half@$$-able cam, it just never Half@$$es it again.
HOWEVER, it is true that the cam lobes for the 4 part time cylinders are SLIGHTLY different from the other 4 lobes for the full time cylinders.
Over a long enough period of time, this V8 will eventually become two similar yet slightly different V4s sharing a common crank,
which would likely lead to asymmetrical bearing wear on a long enough timeline.
Volumetric Efficiency tables for Half@$$-able cams, are SLIGHTLY different from VE tables for full time V8 cams.
Misfire detection tables for Half@$$-able cams, are SLIGHTLY different from VE tables for full time V8 cams.
There are other differences that don't come to mind right now.
*Disabling Engine Half@$$ just turns off that feature-bug, no cam specs are being changed because the same cam is still in use.
*If you DELETE Engine Half@$$, but for some strange reason, you keep the Half@$$ cam, then your tuner leaves those parts of the tune alone,
and you keep driving around with a pair of 2.7L V4s sharing a crank and a block.
*Most people delete Engine Half@$$ more thoroughly, with a Full@$$ V8 cam, which requires changing those things in the tune.
Marky Dissod
Full Access Member
AI is ruining your brain, and everyone else's, gottdamnt!
8th digit from the left! We read from left to right, remember?
LMG 5.3L Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More
From cylinder heads to the camshaft, here's a complete rundown of all the vital engine specs you need for the 5.3L LMG LS engine.
www.onallcylinders.com
Your cam is Half@$$-able (although your cam does NOT have/use Variable Cam Timing).
So, if you DELETE ENGINE HALF@$$, you SHOULD replace your cam with ANY 5.3L cam from ANY full time 5.3L V8, which should include:
LM7 / L59 / LM4 / L33 / LH8 / LH9 / LMF
(I'm the type of guy that'd try to figure out if a GM OE 6.0L cam from a L76t/LY6/L96/ would be an upgrade, butt I haven't finished investigating that thought yet.)
Don't worry, my brain was mush long before AI came around, LOL. My confusion was because I'm used to a letter designator for the engine, and having a number made my 2 remaining brain cells short circuit!
Anyway, here's my problem with what you're saying... bearing in mind the trust I have in ANY of the information I can find is somewhere between my kid saying they didn't eat the cookie and my dog saying they didn't duke on the floor...
The LMG specs I can find are:
Duration @ 0.050in (int/exh): 193 deg/193 deg
Lift (int/exh): 0.482 in/0.482in
Seperation: 116 deg
Cam gear: 1 bolt
While the LM7 specs are:
Duration @ 0.050in (int/exh): 191 deg/190 deg
Lift (int/exh): 0.457 in/0.466 in
Seperation: 114 deg
Cam gear: 3 bolt
Those are pretty different cams, aren't they?
And I still can't find anything that gives any specs for AFM lobes vs non-AFM lobes on the LMG cams.
My head hurts again, LOL
To further confuse the issue....the cam specs address the normal lobes. The afm lobes are different yet. Different slope angle, etc. It's like they haven't figured out how to post cam specs on those, because until now, all cam lobes on a cam are expected to be the same. Notice nobody makes an 'aftermarket' performance cam for an AFM system?
Marky: Well said and explained.
Marky: Well said and explained.
