CAN HYDRAULIC ROLLER LIFTERS RE-PRIME WITHOUT TAKING THEM OUT?

  • Tiny
  • gearhead90
  • 2006 GMC Envoy
  • 108,000 miles

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?

Monday, July 23rd, 2012 AT 4:59 PM

10 Answers

  • Tiny
  • hmac300
  • Expert
  • 42,073 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

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Monday, July 23rd, 2012 AT 5:04 PM
  • Tiny
  • gearhead90
  • Member

How do it check the fuel pressure? The motor has a ticking noise but it is getting quiiter.

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Monday, July 23rd, 2012 AT 5:07 PM
  • Tiny
  • hmac300
  • Expert
  • 42,073 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

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Monday, July 23rd, 2012 AT 5:11 PM
  • Tiny
  • gearhead90
  • Member

Ok now if the fuel pressure is not in the PSI range what would be the next step?

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Monday, July 23rd, 2012 AT 5:13 PM
  • Tiny
  • hmac300
  • Expert
  • 42,073 posts

Replace the fuel pump or filter.

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Monday, July 23rd, 2012 AT 5:14 PM
  • Tiny
  • gearhead90
  • Member

Ok fuel pressure is at 56PSI so that is good. Any other ideas what could be causing the miss?

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Monday, July 23rd, 2012 AT 5:24 PM
  • Tiny
  • hmac300
  • Expert
  • 42,073 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.

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Monday, July 23rd, 2012 AT 5:26 PM
  • Tiny
  • gearhead90
  • Member

Ok the code that is coming up on my code reader is P0301 and all it says is cylinder #1 misfire.

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Monday, July 23rd, 2012 AT 5:29 PM
  • Tiny
  • gearhead90
  • Member

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

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Monday, July 23rd, 2012 AT 5:52 PM
  • Tiny
  • hmac300
  • Expert
  • 42,073 posts

Broom sticks aren't that reliable. If you have changed plugs, wires and coil then do what I said in last answer

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Monday, July 23rd, 2012 AT 7:01 PM

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