Short block purchase

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

OP
OP
flynn78us

flynn78us

TYF Newbie
Joined
Dec 20, 2020
Posts
21
Reaction score
9
I think you guys have convinced me to look onward. Should I start a new advise post or put it in this one? Basically knowing I have a non deleted 11 LC9 with 184ish k miles and a repeated number 8 misfire that comes and goes after plug replacement what are my next steps. Buy a stock 6.0 for a little more power, get another 5.3 and rebuild it?
 

j91z28d1

Full Access Member
Joined
Feb 28, 2022
Posts
2,020
Reaction score
2,323
I think you guys have convinced me to look onward. Should I start a new advise post or put it in this one? Basically knowing I have a non deleted 11 LC9 with 184ish k miles and a repeated number 8 misfire that comes and goes after plug replacement what are my next steps. Buy a stock 6.0 for a little more power, get another 5.3 and rebuild it?



I find the money spent doesn't hurt as much when you can consider it an upgrade. I vote 6.0.

as a in the mean time it could be interesting type thing, you could do the procedure dojetman did to his, to maybe unstick any rings, might help with #8 and add a 30$ catch can if you haven't to try and catch some of the oil going in while you look around. I do agree a 180k active afm on a vehicle you can't have go down would worry me too.
 

Geotrash

Dave
Supporting Member
Joined
Feb 16, 2018
Posts
5,661
Reaction score
13,477
Location
Richmond, VA
I think you guys have convinced me to look onward. Should I start a new advise post or put it in this one? Basically knowing I have a non deleted 11 LC9 with 184ish k miles and a repeated number 8 misfire that comes and goes after plug replacement what are my next steps. Buy a stock 6.0 for a little more power, get another 5.3 and rebuild it?
We have guys on here with over 400K on their original AFM-equipped 5.3's. I'd be more inclined to troubleshoot the one you have. Misfires can come from multiple causes, and #8 is not an AFM cylinder, so I'd look at the wiring to the coil and injectors next. The AFM cylinders are 1,4,6,7. Also, are the plugs you're using either OEM or NGK from a known source like Rock Auto or a local parts store? Amazon and eBay are rife with fakes.

Are there any knocking noises accompanying this misfire? Are there any other stored codes when it happens?
 
OP
OP
flynn78us

flynn78us

TYF Newbie
Joined
Dec 20, 2020
Posts
21
Reaction score
9
We have guys on here with over 400K on their original AFM-equipped 5.3's. I'd be more inclined to troubleshoot the one you have. Misfires can come from multiple causes, and #8 is not an AFM cylinder, so I'd look at the wiring to the coil and injectors next. The AFM cylinders are 1,4,6,7. Also, are the plugs you're using either OEM or NGK from a known source like Rock Auto or a local parts store? Amazon and eBay are rife with fakes.

Are there any knocking noises accompanying this misfire? Are there any other stored codes when it happens?
Ticking, now some bucking I put in Bosch platinum plugs in it. Ensured gap was 40. Cleared the code (0308) now it has random misfire. Bucking is new and seems like it may be transmission related but unsure. I bought this truck at just over 90k from an older couple that did all major maintenance in Florida during the winter months on Cape Cod when I was stationed there.
 

Geotrash

Dave
Supporting Member
Joined
Feb 16, 2018
Posts
5,661
Reaction score
13,477
Location
Richmond, VA
Ticking, now some bucking I put in Bosch platinum plugs in it. Ensured gap was 40. Cleared the code (0308) now it has random misfire. Bucking is new and seems like it may be transmission related but unsure. I bought this truck at just over 90k from an older couple that did all major maintenance in Florida during the winter months on Cape Cod when I was stationed there.
These engines are very sensitive to plugs. I can only tell you what I would do if it were mine. The factory plugs are iridium so I would start by replacing all eight plugs with these from Rock auto: https://www.rockauto.com/en/catalog/gmc,2012,yukon+xl+1500,5.3l+v8,1502532,ignition,spark+plug,7212

And wires: https://www.rockauto.com/en/catalog...5.3l+v8,1502532,ignition,spark+plug+wire,7224
 
OP
OP
flynn78us

flynn78us

TYF Newbie
Joined
Dec 20, 2020
Posts
21
Reaction score
9
I put those plug wires on last year in May. Same time I did the Bosch plugs. Went away until this week. I’ll throw the correct plugs in and see what that does.
 
OP
OP
flynn78us

flynn78us

TYF Newbie
Joined
Dec 20, 2020
Posts
21
Reaction score
9
I find the money spent doesn't hurt as much when you can consider it an upgrade. I vote 6.0.

as a in the mean time it could be interesting type thing, you could do the procedure dojetman did to his, to maybe unstick any rings, might help with #8 and add a 30$ catch can if you haven't to try and catch some of the oil going in while you look around. I do agree a 180k active afm on a vehicle you can't have go down would worry me too.
Can’t find the procedure @dojetman did? Is there a link?
 

Forum statistics

Threads
129,345
Posts
1,814,334
Members
92,481
Latest member
preinternet
Top