AFM Disable Options

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j91z28d1

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don't the diesel guys call a "tune" those little piggy back boxes that just trick them into running rich and adding boost? or do they get real tuned ecm's like hpt?


I'm not really a diesel guy, I work on them at work and hate it. the old ones are messy, the new ones are all complete flaming piles of crap that everything breaks constantly on. so I tend to to avoid the nonsense.
 

Doubeleive

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They don't do a 'tune check', because they lack the software to read or download the operational files from the pcm.
They can only check checksums and CVNs.
They had no idea the BlackBear tune was on it because the BlackBear tune had the same checksums and CVNs as GM OE.
And if they were doing that they would reset everything in the process lol
Maybe not if they were just "reading the file"
 

Marky Dissod

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And if they were doing that they would reset everything in the process
Maybe not if they were just "reading the file"
When they connect to a car for inspection at the mechanic,
they canNOT 'read the file'.
They can only check checksums and CVNs.
If those are properly edited prior to the tune being written to the pcm / ecm /tcm,
the 'tune' will go undetected.
 

KC 2013 Tahoe

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As far as the dongle and future implications... yes. The way the dongle works is by basically sending a command over the CAN bus telling the AFM not to engage. Because the ECU is telling it to engage, then the dongle tells it not to, the ECU recognised it's command was not followed and responds in kind by throwing a fault code and illuminating the MIL. Because this would be an undesirable behavior for something that is supposed to "fix" a problem, the dongle therefore constantly erases the fault codes on the ECU so the MIL isn't on.

The problem is, at least in states like Arizona, the way they SMOG test all 1996 and newer OBDII equipped vehicles is by simply hooking up to the OBDII port, verifying no codes, verifying the check engine light works, and verifying all the systems are "ready". With the dongle constantly resetting the error codes, the computer is never "ready". So to pass SMOG in such a state, you have to remove the dongle and the let the ECU reach the "ready" stage, which can take several weeks. During that time, obviously the AFM is active again without the dongle in.

If you're just disabling it to disable it, it's a very small risk of the AFM failing during that period. If, however, like me, you had a radiator blow out and cause a severe overheating issue that left char deposits in your engine, and you remove the mesh filter at the oil pressure sensor because the char keeps blocking it, then removing the dongle becomes almost certainly fatal for the AFM lifters :).

Furthermore, because it is constantly resetting the ECU, other codes that may indicate other issues are effectively hidden. I had 4 pop up once the dongle was gone :).

The performance tuners allow you to simply tell the ECU to stop turning AFM on at all. If it never calls for it, it can't recognize that it didn't respond. Problem solved for good until and unless your ECU is reprogrammed to factory spec.

But again, that's $500 vs $150 or less. The level of risk in your circumstance is something you have to evaluate. I left myself with no choice, though, so don't be me, LOL.

I can't help you with the oil question, unfortunately. I live in Arizona, where 9 months out of the year we fall into the temperature range where 20W/50 is recommended, so I just run 20W/50 full synthetic all year round, which only slightly increases the oil pressure during the "winter". I haven't used anything below 10W/30 in so many years I've almost forgotten they exist, LOL.
I also reside in Arizona (Chandler) and have the AFM delete dongle on our '13 5.3 Tahoe. All I've ever done is remove it from the OBD2 port in my driveway before heading over to the emissions station. All they do there is plug in their cable and start the engine, leaving it in park as they check for any MIL codes. Have never had any fails or issues the two times I've done this (they only require smog every other year). Only difference I see from yours is that our Tahoe hasn't/isn't throwing any codes.

I do change the oil/filter more often than needed (every 4K miles) w/Mobil-1 full synthetic 5w/30W. The insides of the engine are looking good so far at 135K miles from what I can see from inside the valve covers.

Not to start a kerfuffle here but FWIW - I would never run 50W oil in a modern engine. All newer engines have extremely tight clearances compared to engines in the 70's/80's. My '78 Pontiac 400 has .0035" crankshaft main journal clearances and I never use anything thicker than 40W oil in it, even when I take it to the track. Multi-grade oils maintain their viscosity over temperature. They don't thin out when hot unless very old or dirty.

Clearances for the 5.3 and 6.2 Mains: 0.0008-0.0025"; Rods: 0.0009-0.0025"
Oil pressure is reading higher because it can't squeeze enough of that thicker oil through the tight clearances.

I would hazard a guess that the "sludge" your getting in the screen is actually ground up main, rod and camshaft bearing material. There's simply not enough oil flow to provide adequate lubrication to those critical wear surfaces.

I put a lot of faith in the engineers who designed our engines and put 100's of thousands of testing hours into them to determine the best oil viscosity to use. Not about to second guess them on such a critical component.
 

donjetman

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I also reside in Arizona (Chandler) and have the AFM delete dongle on our '13 5.3 Tahoe. All I've ever done is remove it from the OBD2 port in my driveway before heading over to the emissions station. All they do there is plug in their cable and start the engine, leaving it in park as they check for any MIL codes. Have never had any fails or issues the two times I've done this (they only require smog every other year). Only difference I see from yours is that our Tahoe hasn't/isn't throwing any codes.

I do change the oil/filter more often than needed (every 4K miles) w/Mobil-1 full synthetic 5w/30W. The insides of the engine are looking good so far at 135K miles from what I can see from inside the valve covers.

Not to start a kerfuffle here but FWIW - I would never run 50W oil in a modern engine. All newer engines have extremely tight clearances compared to engines in the 70's/80's. My '78 Pontiac 400 has .0035" crankshaft main journal clearances and I never use anything thicker than 40W oil in it, even when I take it to the track. Multi-grade oils maintain their viscosity over temperature. They don't thin out when hot unless very old or dirty.

Clearances for the 5.3 and 6.2 Mains: 0.0008-0.0025"; Rods: 0.0009-0.0025"
Oil pressure is reading higher because it can't squeeze enough of that thicker oil through the tight clearances.

I would hazard a guess that the "sludge" your getting in the screen is actually ground up main, rod and camshaft bearing material. There's simply not enough oil flow to provide adequate lubrication to those critical wear surfaces.

I put a lot of faith in the engineers who designed our engines and put 100's of thousands of testing hours into them to determine the best oil viscosity to use. Not about to second guess them on such a critical component.
The reason the Pontiac had such large clearance was because of the "large" width and diameter dimension of its bearings and thus journals. Poor design, and Pontiac wasn't the only one. All machinists know this. Built my first Pontiac 400 Ram Air III out of my 69 GTO in 1976. The LS engine has smaller dimensions and thus tighter clearances. No machinist/engine builder I know would ever build a 5.3 or 6.2 with less than .0025" clearance.

I've run 0-20 viscosity oil in our 07 Denali 6.2 for two oil change intervals, when the engine had 183k miles to 195k miles without any ill effects. I've also run 5-40, 5-30 10-30, and 0-40, all with good results. I would run a 50w oil in any of my vehicles without worry. Until about 2010 I ran Valvoline VR1 20-50 in anything I owned without issue.

Oil back in the 70s and earlier was sewage compared to today's oils.

Government corporate average fuel economy (C.A.F.E.) regulations and $fines$ have forced engine designers and auto makers to recommend thinner oils than they would otherwise. The same engines/vehicles sold in other countries without CAFE usually recommend thicker oil. The latest boondoggle engine designers and auto makers have forced upon us because of regulation is direct injection. Oil manufactures/blenders have been forced to come up with new oil specs to try to counter the enegative effects of direct injection. Many new car engines run 0-8 and 0-16 viscosity engine oil.

All of todays engine oils are blended to meet SAE spec and do a lot of ASTM testing. See the charts below to see velocity results at 40c (104f), 100c (212f), and 150c (302f).
They show how greatly oil thins with heat.
viscosity charts.jpg
and
Chart SAE J300.jpg
 
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KC 2013 Tahoe

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The reason the Pontiac had such large clearance was because of the "large" width and diameter dimension of its bearings and thus journals. Poor design, and Pontiac wasn't the only one. All machinists know this. Built my first Pontiac 400 Ram Air III out of my 69 GTO in 1976. The LS engine has smaller dimensions and thus tighter clearances. No machinist/engine builder I know would ever build a 5.3 or 6.2 with less than .0025" clearance.

I've run 0-20 viscosity oil in our 07 Denali 6.2 for two oil change intervals, when the engine had 183k miles to 195k miles without any ill effects. I've also run 5-40, 5-30 10-30, and 0-40, all with good results. I would run a 50w oil in any of my vehicles without worry. Until about 2010 I ran Valvoline VR1 20-50 in anything I owned with issue.

Oil back in the 70s and earlier was sewage compared to today's oils.

Government corporate average fuel economy (C.A.F.E.) regulations and $fines$ have forced engine designers and auto makers to recommend thinner oils than they would otherwise. The same engines/vehicles sold in other countries without CAFE usually recommend thicker oil. The latest boondoggle engine designers and auto makers have forced upon us because of regulation is direct injection. Oil manufactures/blenders have been forced to come up with new oil specs to try to counter Seenegative effects of direct injection. Many new car engines run 0-8 and 0-16 viscosity engine oil.

All of todays engine oils are blended to meet SAE spec and do a lot of ASTM testing. See the charts below to see velocity results at 40c (104f), 100c (212f), and 150c (302f).
They show how greatly oil thins with heat.
View attachment 437979
and
View attachment 437980
Good detail! Don't even get me started on Direct injection! Just read all the posts on here from the new Tahoe/Denali/Sierra owners with seized or destroyed new engines. Ford having similar issues on their Direct Injected engines too. Very happy to keep driving our '13 Tahoe. Kevin
 

j91z28d1

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So, what's the best* oil?


a more loaded question has never been asked lol.

Application, usage, history and condition of engine. what do you want from your oil? does price matter, change intervals you're OK with? common failure points of the engine type. operating Temps and Ambient Air Temps.

so basically I don't know what best lol, even if I knew all that stuff lol.
 

Charlie207

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a more loaded question has never been asked lol.

Application, usage, history and condition of engine. what do you want from your oil? does price matter, change intervals you're OK with? common failure points of the engine type. operating Temps and Ambient Air Temps.

so basically I don't know what best lol, even if I knew all that stuff lol.

Yeah, the * was there for hyperbole warnings.
 

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