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elrudo
New User
Sep 19, 2015, 9:12 AM
Post #1 of 6
(3017 views)
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2008 Silverado AFM issue
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I have a 2008 Silverado with a 5.3 and active fuel management. Had a collapsed lifter for the intake valve on #7. Changed the lifter but on start up it acts like it is being deactivated, won't open the valve. Unplugged the system at the back and acts the same. If I turn the motor over by hand it works, opens the valve. Can't quite get why only one valve is affected. Can't quite understand why either lifter is affected. Haven't seen this problem on any post or fourm.
Cheers
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kev2
Veteran
Sep 19, 2015, 11:37 AM
Post #2 of 6
(3005 views)
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Re: 2008 Silverado AFM issue
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have you considered AFM elimination kit?
you did get the new series (modified) lifter?
when engine running the lifter is collapsing - the difference is oil pressure could be a leak at the oil solenoid...did you scan for codes p3447 p34xx ? ? could also be mechanically stuck open.
(This post was edited by kev2 on Sep 19, 2015, 11:53 AM)
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elrudo
New User
Sep 19, 2015, 6:19 PM
Post #3 of 6
(2993 views)
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Re: 2008 Silverado AFM issue
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Not my truck so haven't considered a elimination kit. More because I don't know that would fix the problem.
Got the lifter from a dealer. They didn't mention if it was one that would work.
I am not that clear on how the solenoid works. Took them off and examined the seals and couldn't see anything obvious.. No scan. Didn't run long enough. Saw there was a problem and shut it down. If it was mechanically stuck then it probably wouldn't work when turning it by hand? I also am unclear why there was a problem in the first place. I haven't seen anybody in a fourm that spoke about why there is a problem with these lifters.
Thanks for your input
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kev2
Veteran
Sep 20, 2015, 7:56 AM
Post #4 of 6
(2972 views)
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Re: 2008 Silverado AFM issue
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I think GM suggests all lifters be replaced if you open it up.
engine off -turning over manually you claim lifter opens valve... but when started lifter collapses, SOUNDS TO ME AS IF AFM IS active...
why no scan? the solenoids and VLOM? will report issues. and a scanner will allow control over solenoids to help diagnose ?
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koontzy
User
Aug 9, 2016, 7:43 PM
Post #5 of 6
(2739 views)
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Re: 2008 Silverado AFM issue
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you may wont to look at the cam as well when i lost a lifter it took out the lobe on the cam still moved the rocker arm but not enough to fully open the valve and on the same hole i was told it could have been a bad cam or the cam break in was not dun right, i thank it is more oil related
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Aug 9, 2016, 8:06 PM
Post #6 of 6
(2737 views)
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Re: 2008 Silverado AFM issue
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Thread is almost a year old now. Please don't respond to old threads. Closed now unless the OP (original poster) requests it to be reopened. Thank you,
T
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