This video is very informative. It’s getting tough for us old shade tree mechanics 50 plus years now for me. Wish I could of had videos like this in 1970. Thank you.
Thank you so much! I have been watching videos and chasing “problems” for two weeks regarding my 2015 Silverado Ltz 6.2 misfire. This is the FIRST video that provides the perfect amount of info, that is explained in a way that allows me to understand exactly what I need to start looking into. I seriously can’t thank you enough sir.
Hi David, my 2015 6.2 117k miles just collapsed a AFM lifter. Cylinder 7, sent it to dealership, they wanted 4k dollars to do new lifters on bank 1, 8k dollars to do both banks. I brought it home and am doing it myself. I may end up doing a AFM delete. My first time inside a L base engine, which it's a LT. So you may have a collapsed lifter, I have learned AFM actually works off oil pressure. I noticed my oil pressure did go down a little when the "tick" appeared. So if you tackle this and plan on keeping AFM check you oil pressure system, there is a small filter on the valley plate, or vlom. Just some ideas, since I have the same truck. Good luck👍
Excellent video I have the same problem on my Avalanche I will be fixing this in a couple of days .and thank you for your time to help anyone who has the same problem
Thanks for this. Fought a 6.0 suburban for 5 months. Gm good wrench reman motor with 48k miles. Dealer put 3 sets of AFM lifters and 3 of the VLOMs in it in less that 2k miles. Got it back from dealer two days after warranty expired. Sent it down the road. It need the AFM delete in the worst way. Sad it came to that. Rig was clean and straight. First motor broke a ring and cracked a piston at 150k miles on Cylinder 7.
Just earned a subscription, bud! Thanks for the insight. Currently dealing with trouble codes on 2016 Chevy 4.3L with AFM as well. Replaced all plugs, wires, and coils. Same rough idle and engine light and Stability light. Plug 4 was wet and stinky and haven’t checked compression yet. This got me another lane to check. Maybe will pursue a delete if applicable.
Great video exactly what I needed to know a whole different V8 than my old El Camino had that I tore down monthly in high school 😆🤣. These new engines are crazy complicated. Thanks a lot 👍🤠
I’m in the process of this problem and did everything you did and came to the same conclusion. Very good video I’m about to pull the head and replace my 4 lifters tomorrow
Nice video. I just replaced my lifters in my 2011. All lifters and dod lifters. Dead hole in 4. Turned over motor with valve cover off, and all are moving. Swapped everything as you did and still runs rough..🤷🏼♂️
Great video. I have a P0300 and is really bad. I changed the spark plugs and wiring and checked a my injectors and wiring and coils and everything is fine. We fix the timing on it cause it was off by 1 point and put a new oil pump and camshaft senor. The truck was on in my driveway for 3 hours nice and sound without and issues. I started driving and around the corner it sounded like if a belt was ripping and the misfire started.
2015 Yukon here, started to get bumpy idle and rough low RPM driving. Noticed my oil pressure was only 20lb at idle. I suspicioned the AFM lifter fail issue because I've hated that system since I learned that it existed in my engine. Stupid insane idea to build something as destructive into an engine. I immediately got a Range Technology AFM disabler as soon as I bought the vehicle with 140K on it. It now has 220K and the rough idle just started at 220K. As a diagnostic I put 10/30 oil with Lucas additive in it rather than the GM recommended 5/20 "watery oil" viscosity. Brought the pressure up to 40lb like it should, apparently making the lifters work better, and the idle is almost normal now. It's been suggested to me by a mechanic it could be the lifters or might be an O-ring on the oil pickup tube lowering the pressure and making the (already somewhat damaged) lifters work badly.
Very helpful! Thank you! You have confirmed the diagnosis for 07 Suburban 242K miles. Removing one head, replacing lifters what should that cost? Thanks, again!
So I can run the truck with the valve cover off ? I have a cylinder 1 misfire which is part of the afm like you had mentioned! I did all spark plugs first for a cheaper fix still through a p0301 code. I replaced the spark plug wire just for fun, then I replaced coil on #1 still got the code. I cleaned the MAF sensor as I read that can cause issues as well “biometric pressure” also checked the MAP sensor on the throttle body. I changed the injector on 1 and still throwing the code. Running very rough at an idle and fuel consumption has gone up….thanks for the very informative video. I enjoyed it a lot
i got cylinder 4 misfire on my 2017 silverado. I wanted to replace the plugs and wires anyway, but i swapped the coil pack and still got cylinder 4 misfire. i was almost certain it was an injector until you brought up a compression test. (i dont work on cars daily like i did in my 20s) will definitely get a compression check tool since my truck is still under a powertrain warranty. (fuel system excluded obviously)
I'm late to the party, but great video, but I still have a question about the Cold Start and Rough Idle problem I have watched all the videos I can find and yours are the best by far, but still would like to know exactly what is going on. My 2017 Tahoe 5.3 has that short term miss when first started in the mornings. By the time I back out of the drive way, it has cleared up and runs fine until the next cold start. No lifter noise, just rough idling. I would like to know what is causing it to misfire only on cold start ups and for such a short time period. Seems as if it is injectors, it would not be just on cold start ups. Heated oxygen sensors? Carbon deposits? AFM lifters? Seems as if you could install new injectors and still not fix it. Or a new lifters and still not fix it. Both of these could be hit or miss and it just be carbon build up. Sometimes I can clear the code P050D and may stay off for a few weeks before setting again. (It say it is a permanent code). Would like to get to the problem without just throwing parts at it hoping to cure it. As a side note, I have found that if I manually set the tranny in low range and leave it in 5th gear, it never going into the AFM mode. Thanks for letting me ramble on and making a long post.
If you want the engine to crank over and not start you could do a "clear flood" hold your foot to the floor on the accelerator pedal and turn the key to the start position. Holding your foot to the floor while cranking disables the injectors and the engine won't run.
Just yesterday (LOL) I was doing a compression test and the fucking thing was starting on ONE cylinder!! (I was too lazy to figure out how to do it properly so I pulled the easy plugs, wires from the harder ones but left damned #8)
Yes , same symptoms on my 2017 ,5.3 gmc. Brought to dealer they changed injectors , plugs n wire i think. Cost 1200$ Can. Then they said still a problem, n have to go into engine and this was the problem. Now it's happening again my#4. Great n warrenty is over. Also had truck on real time data computer program. This showed faulty c0 monitors, all 4. Changed them n then ran ok for a day. Back on computer n then showed #4 misfire. Also internal work was covered by warrenty, but not now .
I been dealing with 2015 4.3l AFM 170K miles P0304 Watched everything on RU-vid. Found this to to be rich in information. Thanks. Shop did everything swap coils plugs wires. Intake clean, smoker test for leaks. 150psi to 170 and nothing on leak down. Injector balance Used smoke from Mexico ( The good stuff) Nothing at removing the valve covers nothing found. Shop wanted $15K to replace engine. I paid got truck out. I pulled off valve covers to do my own eye to see if rockers moving. All seemed OK. I ran truck with cover off and slowing backed off rocker bolts 8mm 1/4 turn with misfire counter watching. Upon getting to 4th rocker from front on right side. 1/4 turn out misfire was gone. I played a little till rattle and then back tight 1/2 turn and zero misfire. How long with this last? Any day longer is better if I can get a few months get CA smog test passed I can get 2 years more. My puzzler is confused as to what was wrong? This truck since day one had a slight rough idle but NEVER A CODE till Nov 2023 at 168K miles. Could the valve Preload been just off from the factory?????? I could not have gotten here today without this and other RU-vid sites. BTY to remove starter on Crew cab 4.3l 4x4 it must come up out though wheel well and with Frame bolt removed and heat shield removed. All other Silverado starters can drop below. This is too small area.
DID NOT WORK. 2015 LV3 HAS AUTOADJUSTER ROCKER THEY CAN NOT BE MODIFIED . NOW I NEED VALVE JOB AND LIFTERS WELL it was a joy for 5 mins till the rocker bolts got loose. I am a losser!!!!
I have a 2013 suburban with 130000 it’s had a 4 cylinder misfire . 7 months ago . Changed spark plugs new coil new wires new abs sensors . Still had a code . Ran a bottle of sea foam through it and the code went away . Fast forward . 7 months and it’s doing the same thing again . 4th cylinder misfire shuttering breaking alittle white smoke at idle . No power then it shuts off and runs great for about 5 mins the. It goes haywire agian .
Having pretty much the same issues with my 2017 Chevy Silverado 1500 5.3. Mine however started blowing white smoke out of the exhaust, and my traction control light came on when my check engine light started flashing. Swapped out cylinder 4 spark plug and got a P0300 code now. Unplugged ignition coil from cylinder 1 and nothing changed lol had the truck for a year with 80k km on it and already had to do a full tranny rebuild. Thanks for the info!!
Similar problems now, with my 2017, 5.3 Liter. P0300 & P0304 codes (Misc. Misfire, Misfire on #4 Cylinder). The traction light came on, while driving it to the repair shop. Turns out its the Lifter on #4 cylinder! Not a cheap repair to get all new lifters! Even worse to get a newly rebuilt motor!
Excellent explanation!! I'm having this problem for weeks now. My #3 plug misfire, PO303. Live data showed #3. New plugs # 3 was only plug that was dark in color, new wires, and #3 coil. I fiured at169,000 miles it was time to change. Still #3 misfire. So maybe that #3 lifter........Damn
I found out I bent a valve on #7 piston. Think that happened one time I was kind of racing and headed in manual mode held it in gear too long....lol Anyway $1,900 later at the top end rebuilt. the AFM was fine. At 178, 000mil now smooth as a whistle.
What would you check next if you replaced the lifters took head to the machine shop and had them checked and changed plugs wires and coils but still miss firing
Great video one question what you think about the AFM.? Would you consider a Range AFM disabler? So the engine would stay at 8 cylinder?...sorry also its more than one question
Ok, after relentless review, I do agree with the 35+ year master. It is the intake valve rocker arm that is not moving and not the exhaust valve rocker arm on no. 4 cylinder. Please except my humble appology.
I have an 11 Yukon with afm. We had a collapsed lifter on number 1. We swapped it out and still see the p0300 and p0301. We did not change the cam because it looked fine. We have spark and fuel with low compression on that cylinder. Probably has a bad cam as well. Curious about your thoughts
I must say that I did own a 2013 AFM silverado...........glad I got rid of it for no doubt another chevy problem down the road. Now, I have a 2016 LML bone stock with extended warranty. Buy Top tier diesel and stay on top of maintenance with minimal idle time. The DEF system is a PIA (twice had to be replaced under "special chevy warranty"; so when warranty runs out, gonna delete, delete, delete!!!!) Mississippi, no emission test. CP4 pump may be a problem down the road; yet, as for now, 29,000 high pressure rail and piezoelectric injector arie all good.
I replaced my AFM (all four) on the same side as this vehicle. The motor ran great for 2 days (roughly 100 miles). Then cylinder 4 misfire came back just like before. Why would it run well for 2 days?
Will this cause a oil pressure spike? I always had 40 psi driving and since misfire it spiked to 65 psi. I've changed injector and still misfires on number 6.
I learned so much from this video and I have a couple routes I’m looking to take in order to hopefully fix my truck. So I got a misfire code p0304 and a O2code and the stabilitrak/traction control and check engine came up on my 07 Sierra 5.3. What I did was changed all my spark plugs with Bosch plugs and after doing this my truck actually got worse, my mechanic said that ac delco spark plugs are recommended for my engine. After that the p0304 code took off and now I have a p0300 code, I did change the coils, wires, cleaned the throttle body and mass air flow sensor and nothing helped. What I also did was shoot water all around my intake gasket and I did have a tiny vacuum leak but I’m not sure if that can be big enough to make my engine misfire. I’m now wondering if it’s the rocker arm with the afm that’s messing up. Any recommendations?
same symptoms except 0306 instead of your 0304. (With stabilitrak code) switched wires/coils also. Shined up all grounds. (wire wheel on drill) Including under dash pad. then installed delete module (OBD port) cleared all codes at battery cables. zero problems since. runs and shifts better. 2014 Silverado 4.3 V-6. 88K miles. Amsoil 5-30 Will buy another Chevy, but not with the AFM nonsense.
Can you please show how to change it the easier way you said you knew how so you wouldn't have to take it all apart and thank you so much this was the problem!
I got a 4.3 liter AFM motor 2014 Chevy Silverado. Compression test 150, still misfire on cylinder 4. Changed spark plugs and wires, changed the coil, and even changed them all around. Still a misfire on 4. It's driving me crazy trying to find the issue. I can't seem to figure it out any help would be appreciated.
The same thing happened to my 5.3. Turns out the number 6 intake lifter “separated “ from the barrel. Do you feel the need to replace both sides of engine? Odd side and even side. Or just replacement of one side is enough. Thanks
I have a Toyota Camry 2001 2.2 Liter engine 4 Cyl . I have this kinda problem. Flashing engine lights on and Misfire Codes. After changing my Spark Plugs and New wires and New Coil wires .It still Misfires. Then I change my Fuel Injectors Change Oil and put some Lucas Fuel Injector cleaner Still Misfires . This is the Codes that is Showing up P0300 Random /Multiple Cylinder Misfire P0301 Cylinder 1 Misfire P0302 Cylinder 2 Misfire P0303 Cylinder 3 Misfire Now iam thinking changing my Fuel Pressure Regulator .So is this going to solve my problem on my vehicle .I heard some people will say that the timing chain is the problem .and some will tell me that it is Intake Valve Not Setting Properly .
Hey Ron, dealing with one of these in my shop at the moment. In October of 2022 we had one of these in with a dead #7 cylinder, had low compression, pulled the head and replaced all the lifters ran perfect for 900 miles, however just came back with the same cylinder misfiring. This time it has compression, pulled the VC and the intake rocker isn't moving with when the engine is running, however it has full motion when turned over by hand. I find it really hard to believe the same lifter in the same cylinder is bad again. Leaning more towards the VLOM keeping that lifter on. Thoughts?
I have the exact same problem. I am leaning toward the solenoid on the VLOM is stuck open on my number 6 cylinder and causing a miss at idle because when I rev the engine it smoothes out and the check engine light stops flashing. The VLOM is not supposed to activate at idle.
I have my 2022 Chevy suburban 5.3 Have missfired cylinder 3 We change 16 lifter camshaft spark plug and wires , injector still the same problem took it to the dealer on aptil 15 untill today they didn’t know what the problem they told me it’s a mystery any idea guys what I should do
Why would you have the intake off and only change them on one head My goodness go ahead and get both heads both sets of lifters on you know on each side of the engine
What do you think about using a AFM Disabler Device? For a 5.3 Chevy Silverado Z71 LT crew cab truck with 36,000 miles. Had a misfire on cylinder 4 at 20,000 miles. Good video! Be safe! 7/17/2023
@@SandCarServicesWhat? Really? You'd goto jail for doing a modification to YOUR own vehicle? Its Not like its a exhaust emmissions device. It just saves fuel!
My 2015 Silverado has the same exact problem. Cylinder 7 misfire. Replacing all the AFM lifters and deleting that BS crap off the computer. Can’t believe GM did it this way.
I am getting ready to shoot a video on vibration during AFM. Replace your engine mounts with delco only. If your getting a feeling like driving over those rumble strips as your slowing down.
@@SandCarServices i can feel something like vibrations on any speed till 80 mph, without Range Device. It looks like something engaging then disengaging constantly. First time a thought about bad torque converter but it's a afm :(
@@SandCarServices i went to diagnostics. He found misfires but could not say the exact cylinder. He checked every igniter plug and coil with special tool, they are OK. You mean I need check with GM service scanner?
Well it's getting late for me tonight was trying simple diag on mine now looking like I need more intensive approach and help from a real mechanic on my 2011 silverado 1500 5.3 atless I have a good mechanic near by to help
My Tahoe ppv has the same misfire on cylinder #4. I was driving on freeway heading home maybe about a 15 mile drive when I stopped to put gas and sounded like i was low on oil . Over those 10-15 miles tick got worse and worse. I plan on replacing the lifter because that’s what I’m expecting it is. Hoping maybe the push rod broke unfortunately so I don’t have to pull the head lol
@@andrersnandez8568 I fixed the problem. It only costed me about $10. I ended up swapping the coil packs to see if it fixed the problem but it did not. Cyl 4 still was bad. My next check was going to run a compression test on cyl 4 but when I pulled the plug out I noticed it had a long crack on it. I replaced the plug and everything ran normal again. I use AC Delco OEM plugs. These had about 30k miles on them. I went ahead and swapped them all out again.
@@andrersnandez8568 The actual spark plug ceramic was cracked. I don't know if it was just a coincidence but that was the problem. I have never had one crack on me. The wires were good.
I took my truck to the shop last week I started hearing a loud ticking from motor no check engine light. The tech called said I had a miss fire on cylinder 4. I've done a good bit of research and I haven't seen any one else have a miss fire and no check engine light absolutely no loss in power not driving bad nothing but a continuous knocking noise. Is that common
I have a 2021 gmc sierra x31 5.3 v8. My check engine light would flash about 8 to 10 times and going away when starting the day and leaving the house. It did that maybe 3 times randomly within a 3 month period. I started putting gas treatments every fill up. I would get the high octane orange gas treatment assuming it was slightly better than the dollar store one. I noticed that the flashing check engine light stopped since I was using that gas treatment. Well recently my last 2 to 3 fill ups I dint use a gas treatment. This past Sunday the check engine lit up and stayed on rather than blinking and going away. So I went to auto zone and put the computer on it to get a code and a P0300 came out only. Which was a misfire caused by or due to fuel injector. That was stated on the print out. Suggested instructions stated to clean fuel injection system. I put some seafoam large can with half of tank and just today after driving it about 30 miles the check engine light went off. Im at 19,700 plus miles. My first scheduled service is at 22500 miles. Im hoping to have the light turn on again for when I take it to get serviced so they can replace the lifters since its still under the 6 yr 100,000 mile power train manufacturer warranty. Not sure if its the gas causing the misfire when not putting gas treatments on every fill up. Or if its just the lifters and push rods that just suck in these engines. I hope gm corrects this issue soon with the class action lawsuit going on and all.
My QUESTION IS....WTH couldn't GM just shut off the fuel to those 4 cylinders when the engine isnt under load ??? I don't understand why flatten the valves ?? That doesn't make sense to me
