'15 Sierra Injectors misfire ?...UPDATE

Beer Belly · May 10, 2018

My Sierra is at the dealer for the past 3 days. Truck was misfiring bad, Check Engine Light and Traction Control Light came on.....lasted a few minutes, then went back to normal for about 30 seconds, then everything went back to hell, only to go back to normal a block from the dealer. Code being thrown was an entire bank of Injectors Misfiring, the Tech said he's likely going to have to replace all the Injectors.....now they tell me GM rejects any repair unless they can duplicate the problem.....so far, the truck hasn't had an issue while they've had it, and they want me to pick it up tomorrow. I carry my Wife and Pup in this truck and tow our camper.....not feeling all that confident in this thing. It has 32,000+ miles on it, and will bet it will fall apart just outside the 3/36 Warranty. Any input on issues or similar incidents appreciated.

Edited July 10, 2018 by Beer Belly

crushNchowda · May 10, 2018

My '15 w/ 6.2 & 8 speed started getting valve tick making a hell of a clatter, brought it in for that while doing the repair they confirmed entire bank of lifters on right side were bad "#4 intake valve push rod bent, replaced all AFM lifters right bank, also replaced AFM manifold, had difficulty removing left side injector rail due to corrosion had to replace #8 & #6 fuel injectors since damaged when removing fuel rail" Truck had 46,300 EASY miles on it at the time.

AFM/DOD & all the associated hardware is JUNK, & IMO (although not really my opinion I think the consensus is FACT) the AFM stuff actually causes unneccesarry wear/tear on other associated/interacting components such as the torque converter, transmission, injectors/fuel rail (as far as I'm concerned small block SOHC V8's should be having all cylinders/injectors/valves functioning ALL the time to endure an even duty/wear cycle - AFM = GM's quick fix bandaid to appease Obama era CAFE standards) IT IS GARBAGE & RUINING THEIR PRODUCTS

Plus side is we have 2015's that get 100k powertrain, GM reduced to 60k...wonder why eh?

That being said, if I have another lifter drop I'm having GM fix it + push to replace as much other hardware as possible in addition, then I'm gonna yank a bunch of it out & have a DOD/AFM delete cam kit installed & be done w/ it.

As James Hetfield says, "You know it's sad but true!!!!!!"

amxguy1970 · May 10, 2018

Nope, just your opinion and far from fact. A few failures every so often is par for any engine regardless of manufacturer, type or parts on it. For every failure there are thousands of them without an issue. AFM works great and as advertised gaining some mpg and being flawless in its activation, I have yet to know a person who knows a person with a failure. Buddy just got rid of his Tahoe with it at around 250k, no oil consumption, failures, noises, ect. Go around calling it junk and saying it causes transmission shifting issues ect is just plain false. You may be upset, but no need to spread info like that. For a forum being the gathering point of upset people and failures they sure are few and far between... I am more happy with this set up then I would with a small displacement turbo 6 for longevity. Now do I agree an all V8 mode engine is more reliable with less chances to break, sure most likely; but for what it is and they have done it is an extremely reliable and trouble free system for most everyone.

Yes after saying that it is possible I will have a failure soon but I highly doubt it.

Sucks OP but maybe having it reset and stuff being pulled apart and reassembled properly fixes a connection or something, rogue issues do happen and never pop up again (like AFM failures), it is up to you if you want to trust it or not.

Tyler

crushNchowda · May 10, 2018

11 minutes ago, amxguy1970 said:

Nope, just your opinion and far from fact. A few failures every so often is par for any engine regardless of manufacturer, type or parts on it. For every failure there are thousands of them without an issue. AFM works great and as advertised gaining some mpg and being flawless in its activation, I have yet to know a person who knows a person with a failure. Buddy just got rid of his Tahoe with it at around 250k, no oil consumption, failures, noises, ect. Go around calling it junk and saying it causes transmission shifting issues ect is just plain false. You may be upset, but no need to spread info like that. For a forum being the gathering point of upset people and failures they sure are few and far between... I am more happy with this set up then I would with a small displacement turbo 6 for longevity. Now do I agree an all V8 mode engine is more reliable with less chances to break, sure most likely; but for what it is and they have done it is an extremely reliable and trouble free system for most everyone.

Yes after saying that it is possible I will have a failure soon but I highly doubt it.

Sucks OP but maybe having it reset and stuff being pulled apart and reassembled properly fixes a connection or something, rogue issues do happen and never pop up again (like AFM failures), it is up to you if you want to trust it or not.

Tyler

Maybe I should mention then, that I also owned a G8 GT w/ AFM that grenaded as well? Seems like my firsthand experience speaks for itself. Do I think the majority of GM vehicles w/ AFM have major problems, no. Do I think there are a ton of clueless owners that don't even know they have problems b/c they're not "car people" & treat their AFM equiped vehicles like appliances, yes. Do I think there's a SIGNIFICANT (like double digit) percentage of AFM vehicles w/ problems? I'd bet my life savings on it. Absolutely positive that's the case.

Wonder why vendors make packages like this? Must not be a market for it - what a waste of marketing & R&D on Livernois' part.

https://www.livernoismotorsports.com/product/LPP802102

diyer2 · May 10, 2018

I'm not going to try and change your opinion crushNchowda but the fact remains lots of AFM vehicles have no problems.

Not every unit is perfect when it's mass produced, your going to make some bad ones out of millions.

Sorry to hear you seem to get the bad ones.

crushNchowda · May 10, 2018

1 hour ago, diyer2 said:

I'm not going to try and change your opinion crushNchowda but the fact remains lots of AFM vehicles have no problems.

Not every unit is perfect when it's mass produced, your going to make some bad ones out of millions.

Sorry to hear you seem to get the bad ones.

Yeah maybe I have bad luck w/ the GM gods who knows....must be because I also own one of the most reliable bullet-proof (mechanically) best bang for the buck vehicles they've ever produced w/ my '03 Z06 (cammed & bolt-ons etc 450whp) - so out of spite or to just level my karma I get all the junk in my other GM vehicles

BTW - you can get yourself a V8 w/ a big 'ol carb on it if you want, smallblock or big block, LSx all AL or cast iron block you choose - GM still makes some GREAT crate motors w/ carb vs. EFI or DI - & you won't have to worry about AFM crap!!! Gee....then again, if AFM was so great why don't they leave it in the crate engines then? Why do they offer LTx & LSx engines that in factory trim when installed in production vehicles have AFM (performance vehicles) & yet offer them without it as a crate motor? Your guess is as good as mine.....

You're not changing my opinion, but I agree - LOTS of GM vehicles w/o AFM problems, but I also assert MANY do - like I wouldn't be the least bit surprised if it were 10-15% (and since GM + Chevy = most trucks on the road today, that's ALOT of vehicles)

Meh, I digress - its nice out today I'm going to take my GOOD GM vehicle out for a spin & will rely more on my wife's MDX if we're making long road trips these days.....already got stranded once, don't need it to happen again.

Edited May 10, 2018 by crushNchowda

Beer Belly · May 11, 2018

Cannot duplicate, so GM is not authorizing any sort of attempt of a repair, and I will be picking the truck up today. While it was in the shop, had a sales person look it over to see what the numbers are to trade for a new truck....just curious. Wife has lost confidence in GM, and is against me getting another.....I've had terrible luck with the last two trucks. Hopefully this is an isolated incident and it doesn't happen again...fingers crossed

Mike GMC · May 11, 2018

It may have been a clog that cleared, but otherwise machines don't fix themselves so if there is a problem, it will get worse. Take it back when it does. Make sure you get documentation on this visit so when you bring it back, it's a repeat visit. That should help even if you end up going over the warranty period.

M1ck3y · May 12, 2018

You need a new dealership. A code is the one and only time gm actually steps up to the plate.

Edited May 12, 2018 by M1ck3y

Doublebase · May 12, 2018

On 5/10/2018 at 1:48 PM, crushNchowda said:

Yeah maybe I have bad luck w/ the GM gods who knows....must be because I also own one of the most reliable bullet-proof (mechanically) best bang for the buck vehicles they've ever produced w/ my '03 Z06 (cammed & bolt-ons etc 450whp) - so out of spite or to just level my karma I get all the junk in my other GM vehicles

BTW - you can get yourself a V8 w/ a big 'ol carb on it if you want, smallblock or big block, LSx all AL or cast iron block you choose - GM still makes some GREAT crate motors w/ carb vs. EFI or DI - & you won't have to worry about AFM crap!!! Gee....then again, if AFM was so great why don't they leave it in the crate engines then? Why do they offer LTx & LSx engines that in factory trim when installed in production vehicles have AFM (performance vehicles) & yet offer them without it as a crate motor? Your guess is as good as mine.....

You're not changing my opinion, but I agree - LOTS of GM vehicles w/o AFM problems, but I also assert MANY do - like I wouldn't be the least bit surprised if it were 10-15% (and since GM + Chevy = most trucks on the road today, that's ALOT of vehicles)

Meh, I digress - its nice out today I'm going to take my GOOD GM vehicle out for a spin & will rely more on my wife's MDX if we're making long road trips these days.....already got stranded once, don't need it to happen again.

I'm sorry you've had problems with the AFM but I think you are in the minority. Which I'm sure doesn't help matters with you.

There are seven people at my work that own these trucks. Seven. Not including myself (I just bought a 2018). I ask these people how they like their trucks...have they had any issues? They all say no all I do is change the oil and tires. One guy has 180,000 miles on his, I asked him if he had any problems with the AFM, he says, what's the AFM? That little V4 to V8 thingy? That things great I'm averaging 25 mpg on the highway. Another guy has 90,000...he beats the tar out of this thing. Absolutely worst person to ever drive a vehicle. Asked him about the AFM, he just stared at me like I was talking about a meme or something that he's never heard of. 90k miles not one single issue. One women has 55,000 miles on hers...it was down three quarts of oil and I thought....here it is! A failed AFM! The oil filter was lose. Put a new filter on, no problems ever since.

The only thing I can say I've noticed with these trucks is that one of them has a frame that looks very rusted (2014). I mean wow, that frame looks like every ounce of that coating is gone and all that's left is rust. It looks nasty. But mechanically? At least with these people nothing.

I've only owned my truck for a month, certainly don't know what the future holds but I'm AVERAGING 25.1 mpg in the 2,600 miles I've put on it. I figure without the AFM I'd average around 16? Maybe 17? This system should save me around $1,700 a year. Let's say it craps out on me five years from now...how much would I have saved in that time frame on gas? $8,500? What's it going to cost for me to replace all the lifters, and gaskets? $500 if I do it myself? I'm an ASE master certified tech so I should be able to remove the heads and complete the job in a couple of days if I slowly pick away at I while drinking a few beers over the weekend. For me at least it's worth having the AFM (I say that now but I may change my mind when I'm banging my knuckles fixing the thing).

Jon A · May 12, 2018

8 hours ago, Doublebase said:

I'm AVERAGING 25.1 mpg in the 2,600 miles I've put on it. I figure without the AFM I'd average around 16? Maybe 17? This system should save me around $1,700 a year.

Not remotely. Even GM's advertising claims when these engines were introduced were for only 5-7% increase due to the AFM system. You're realistically looking at 1-2 MPG gain or less even in the most favorable driving conditions (lots of low-medium speed cruising on flat ground). Less if you live where there are lots of hills, tow anything, have larger tires, travel at high speeds, etc.

Doublebase · May 13, 2018

14 hours ago, Jon A said:

Not remotely. Even GM's advertising claims when these engines were introduced were for only 5-7% increase due to the AFM system. You're realistically looking at 1-2 MPG gain or less even in the most favorable driving conditions (lots of low-medium speed cruising on flat ground). Less if you live where there are lots of hills, tow anything, have larger tires, travel at high speeds, etc.

So you think I'd average maybe 23 mpg without the AFM, with the way I drive?

My "best" average over 50 miles of driving has been 29 mpg. This week after 570 miles of driving I'm averaging 25.3 (slightly off from last week when it was warmer when I averaged 26.1). I drive 600 miles a week, every week, 70% highway, the rest back country roads doing 40-50 mph.

I've found the best way for me to get maximum fuel economy is to get it up to speed quickly, then back off the accelerator pedal immediately and kind of feather it while maintaining speed. That's the sweet spot...then I'll look down and I'm getting anywayere from 26mpg to 50mpg, just cruising along on back country roads. Then I hit those downhills and boom! I'm getting 99mpg and the momentum carries me half way up the other side of a hill before I even have to hit the gas pedal. Highway I just keep it in cruise control set between 67-70 and I'm averaging 24-30 depending on the incline (as that V4 hums along).

The number one issue I've run into is weather/temperature. If it's under 40 degrees my mpg's dip by about 1 or 2...but on the flip side if it's over 80 degrees? I feel like I'm driving a Prius. I'm getting better gas mileage out of this truck than my wife gets out of her four cylinder SUV. But without the AFM maybe I could average 22? Who knows?

Another thing I'm noticing is that my weekend driving is hurting my overall mpg numbers...the short stuff here and there...going to Home Depot, going out to dinner, sitting in traffic, lots of shorter trips. The 50 mile average ranges from 22-24. Where as Monday through Friday I'm always in the 26 plus range.

Edited May 13, 2018 by Doublebase

Jon A · May 13, 2018

18 hours ago, Doublebase said:

So you think I'd average maybe 23 mpg without the AFM, with the way I drive?

Yeah, that sounds about right given your description of your driving. Plenty of people have reported no noticeable difference after disabling the system, others have reported a small drop. It will obviously vary depending upon the driving conditions and accurately testing mileage is way more difficult than most people realize as traffic, weather, wind, etc, play such a huge role. But in your case, I'd definitely expect a drop, but not a huge one.

Beer Belly · May 15, 2018

On 5/11/2018 at 8:51 PM, M1ck3y said:

You need a new dealership. A code is the one and only time gm actually steps up to the plate.

"Scanned for codes and found PO300 passed. Check misfire data and found misfires in cylinders 1,3,5 and 7. 6900 misfires in cylinder 7. test drove and was unable to to duplicate misfires.Performed cold start test per PIP5498G and found slight slight misfires in multiple cylinders including cylinder 4 but nothing like what the guest experienced. Removed spark plugs and found no obvious issue with the plugs. Installed wire and plug and soaked in warm soap water and ran vehicle. No misfires. Called TAC opened case *-********* due to not having PO50D do not believe it is fuel injector. Instructed to duplicate to proceed"

crushNchowda · May 15, 2018

On 5/12/2018 at 7:46 AM, Doublebase said:

I'm sorry you've had problems with the AFM but I think you are in the minority. Which I'm sure doesn't help matters with you.

There are seven people at my work that own these trucks. Seven. Not including myself (I just bought a 2018). I ask these people how they like their trucks...have they had any issues? They all say no all I do is change the oil and tires. One guy has 180,000 miles on his, I asked him if he had any problems with the AFM, he says, what's the AFM? That little V4 to V8 thingy? That things great I'm averaging 25 mpg on the highway. Another guy has 90,000...he beats the tar out of this thing. Absolutely worst person to ever drive a vehicle. Asked him about the AFM, he just stared at me like I was talking about a meme or something that he's never heard of. 90k miles not one single issue. One women has 55,000 miles on hers...it was down three quarts of oil and I thought....here it is! A failed AFM! The oil filter was lose. Put a new filter on, no problems ever since.

The only thing I can say I've noticed with these trucks is that one of them has a frame that looks very rusted (2014). I mean wow, that frame looks like every ounce of that coating is gone and all that's left is rust. It looks nasty. But mechanically? At least with these people nothing.

I've only owned my truck for a month, certainly don't know what the future holds but I'm AVERAGING 25.1 mpg in the 2,600 miles I've put on it. I figure without the AFM I'd average around 16? Maybe 17? This system should save me around $1,700 a year. Let's say it craps out on me five years from now...how much would I have saved in that time frame on gas? $8,500? What's it going to cost for me to replace all the lifters, and gaskets? $500 if I do it myself? I'm an ASE master certified tech so I should be able to remove the heads and complete the job in a couple of days if I slowly pick away at I while drinking a few beers over the weekend. For me at least it's worth having the AFM (I say that now but I may change my mind when I'm banging my knuckles fixing the thing).

I don't get anywhere close to that mileage w/ any of em - '13 5.3 w/ wimpy 3.08 rear, my 5.3 w/ 3.42's avg'd 16.4mpg over 44,000 miles or so when it was totaled, my '15 6.2 gets 16 flat avg over the last 50,000 miles - it is actually a little better because I have 1" taller tires & having recalibrated- and I drive a lot of hwy miles, but I also do a good bit of idling & around town errand running. At the end of the day AFM or no, I think once you're driving over 75mph, mileage drops like a rock. I do not believe people who claim low/mid 20's MPG if they're going 80 on cruise control at sea level even, from what I have experienced, not possible. Now doing 65-72mph - totally different.

My experience w/ DOD/AFM on my G8 GT & '07 silverado 5.3 is that it made at most .5-1mpg difference net after I tuned it out everything else the same otherwise.

IMO it is a "parlor trick" geared @ making the trucks perform exceptionally well on closed course driving under the right parameters needed to look good for the CAFE regulations. In the real world AFM does nothing for me other than provide for a clunky tranny & torque converter & a crappy sounding exhaust note.

Thanks Obama!