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Username Post: Misfire        (Topic#359381)
chevyisland 
Senior Member
Posts: 632
chevyisland
Loc: Trinity, TX
Reg: 07-18-03
01-05-20 10:19 AM - Post#2783748    

2011 GMC Sierra 1500 SLE, had friend run his scan tool on it, and it came up cylinder #7 misfire. Any ideas as to the problem? Plugs? Coil? Wire? Any help would be appreciated.

2011 GMC SIERRA SLE 1500
1966 Thunderbird Tudor


Edited by chevyisland on 01-05-20 11:02 AM. Reason for edit: No reason given.

 
Shepherd 
Frequent Contributor
Posts: 1911

Loc: Lake George, NY
Reg: 11-11-15
01-05-20 11:34 AM - Post#2783751    
    In response to chevyisland

Plug, wire, coil, dead injector, most common possibilities .



 
chevyisland 
Senior Member
Posts: 632
chevyisland
Loc: Trinity, TX
Reg: 07-18-03
01-05-20 01:33 PM - Post#2783756    
    In response to Shepherd

That helps a lot, thanks

2011 GMC SIERRA SLE 1500
1966 Thunderbird Tudor


 
rockfangd 
"6th Year" Gold Supporting Member
Posts: 2852
rockfangd
Age: 33
Loc: Utica ny
Reg: 04-13-10
01-05-20 04:03 PM - Post#2783767    
    In response to chevyisland

Try swapping the coil with another cylinder to see if it moves with it.
That would be my first guess.

Old School GM fan FOREVER


 
YOUNG57 
Frequent Contributor
Posts: 1176

Loc: Tennessee
Reg: 12-06-10
01-05-20 07:22 PM - Post#2783777    
    In response to chevyisland

Cylinder #7 is one of those deactivated by the AFM. One or more of the special AFM lifters may have failed holding valves open or closed.

You might run a compression check on that cylinder to help diagnose if it is a AFM issue.




 
junkman104 
Frequent Contributor
Posts: 1465
junkman104
Age: 60
Loc: Murphy N.C.
Reg: 01-25-14
01-06-20 04:20 AM - Post#2783798    
    In response to YOUNG57

I have a 13 model in the shop just put the heads back on after replacing all the AFM lifters for the same issue. I will finish the job today.




 
YOUNG57 
Frequent Contributor
Posts: 1176

Loc: Tennessee
Reg: 12-06-10
01-06-20 08:46 AM - Post#2783812    
    In response to junkman104

You replaced the bad AFM lifters with new ones…

When the 60 month/100k miles warranty on my 2014 Yukon ended last year, I had it reprogramed deactivating the AFM to stop wear and tear on the stupid AFM lifters which start to fail between 100k and 300k miles.

Before I deactivated the AFM I got 17.3 average MPG highway, now I get 19.1, go figure.

If any of my AFM lifters do fail, I will get one of the kits that replaces them, the cam and cover plate that activates them to make it like a pre-2007 LS 5.3.




 
junkman104 
Frequent Contributor
Posts: 1465
junkman104
Age: 60
Loc: Murphy N.C.
Reg: 01-25-14
01-06-20 04:16 PM - Post#2783844    
    In response to YOUNG57

I do what the customer wants. Personally I will never own a AFM engine, but would delete it if I did.



 
rockfangd 
"6th Year" Gold Supporting Member
Posts: 2852
rockfangd
Age: 33
Loc: Utica ny
Reg: 04-13-10
01-06-20 06:30 PM - Post#2783864    
    In response to junkman104

I agree on the AFM cylinder dropout but before confirming that start with easy

Old School GM fan FOREVER


 
YOUNG57 
Frequent Contributor
Posts: 1176

Loc: Tennessee
Reg: 12-06-10
01-06-20 07:53 PM - Post#2783871    
    In response to rockfangd

A compression check on that cylinder is a cheap and easy way to help diagnose if it is a AFM issue.




Edited by YOUNG57 on 01-06-20 07:55 PM. Reason for edit: No reason given.

 
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