can hydraulic roller lifters re-prime without taking them out?

2006 GMC ENVOY
108,000 MILES
Avatar
GEARHEAD90
  • MEMBER
  • 6 POSTS
i have a 2006 envoy denali with the 5.3L. it has a misfire on cylinder #1 and iv changed the oil since it was losing oil pressure, changed spark plugs and wires and even replaced the coil pack for the cylinder and it still has a misfire. could a lifter have lost its prime and causing the misfire and if so do the hydraulic roller lifters re-prime themselves with the engine running?
Jul 23, 2012 at 4:59 PM
Advertisement
Avatar
HMAC300
  • CERTIFIED EXPERT
  • 48,601 POSTS
check fuel pressure first as that will cause a misfire as well. then check for a vacuum leak. lifters will reprime themselves as long as there is oil pressure.if the lifter collapsed it would make a very loud ticking noise then go away after a few seconds
Jul 23, 2012 at 5:04 PM
Avatar
GEARHEAD90
  • MEMBER
  • 6 POSTS
how do it check the fuel pressure? the motor has a ticking noise but it is getting quiiter.
Jul 23, 2012 at 5:07 PM
Advertisement
Avatar
HMAC300
  • CERTIFIED EXPERT
  • 48,601 POSTS
you will probably need an adapter to tap into the fuel rail. most auto parts stores have them to rent. if you are lucky there will be a tap on the fuel rail where you can check it. it should be55-62 psi at idleor with key on andengine not running
Jul 23, 2012 at 5:11 PM
Avatar
GEARHEAD90
  • MEMBER
  • 6 POSTS
ok now if the fuel pressure is not in the PSI range what would be the next step?
Jul 23, 2012 at 5:13 PM
Avatar
HMAC300
  • CERTIFIED EXPERT
  • 48,601 POSTS
replace the fuel pump or filter.
Jul 23, 2012 at 5:14 PM
Avatar
GEARHEAD90
  • MEMBER
  • 6 POSTS
ok fuel pressure is at 56PSI so that is good. any other ideas what could be causing the miss?
Jul 23, 2012 at 5:24 PM
Avatar
HMAC300
  • CERTIFIED EXPERT
  • 48,601 POSTS
check compression and vacuum leak spray choke cleaner for a vacuum leak around intake area also look for vacuum hoses off or holes in them. what is the correct code you are getting.
Jul 23, 2012 at 5:26 PM
Avatar
GEARHEAD90
  • MEMBER
  • 6 POSTS
ok the code that is coming up on my code reader is P0301 and all it says is cylinder #1 misfire.
Jul 23, 2012 at 5:29 PM
Avatar
GEARHEAD90
  • MEMBER
  • 6 POSTS
i used a broomstick and put it by cylinder 1 and i could hear some ticking. its starts fine but after it runs for about 30 sec it bogs down and then you can really tell its missing
Jul 23, 2012 at 5:52 PM
Avatar
HMAC300
  • CERTIFIED EXPERT
  • 48,601 POSTS
broom sticks aren't that reliable. if you have changed plugs, wires and coil then do what i said in last answer
Jul 23, 2012 at 7:01 PM