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Sergio Quiroz

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About Sergio Quiroz

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  1. Yes, just make sure you're on the base of the lobe. If you're removing the intake side, you can spin the engine til the exhaust valve is open and vice versa. Make sure to torque to 22ft lbs when putting the rocker back on.
  2. Well aren't we lucky! Lol I've checked play on the rockers and have very little side to side and none up/down which I believe is all normal. I'm guessing my compression test is gonna come out fine too. I can't imagine the lobe having a flat spot affecting compression. Do you have any noise? I'm thinking I'm going to put my stethoscope on that rocker bolt and compare to an other one just for the giggles. Gonna check that pushrod too and make sure it's still straight.
  3. No blowby noticed. I'm buying a leak down tester tomorrow and checking that. Spark plug looked fine so I don't think the head gasket is leaking coolant either. On second thought, since both valves have to be on the base of the lobe for the leak down test would a leak down test even help diagnose anything if the cam lobe is messed up?
  4. No abnormal noises. If anything I think it's quieter than the valvetrain in my LS3 Camaro.
  5. I don't have any way of measuring valve lift with any sort of accuracy. I will check the pushrod to see if it's bent. Injector 5 is definitely firing.. I have constant 12v and ECU ground signal to it. Tested with noid light and flickers while engine is running, swapped injectors, can hear it clicking with stethoscope. Wiring looks fine without tearing the harness apart. Haven't done compression test yet. I'll need to rent or buy a tester. I'll have to try unplugging the coil while the rocker is backed off to see if misfires come back. Good idea. I can't wrap my head around why the misfire stops when backing off the rocker... Could the lifter plunger be stuck all the way at the top essentially making it longer and causing that valve to open more than it should? I can see oil squirting out of that pushrod so that tells me the plunger/lifter is doing its job right? I'm still not 100% sure about my intake leak test... I may try that again or take it off to check the gasket. Could a vacuum leak explain the misfire stopping by backing out the rocker? Thanks for replying by the way. Bouncing ideas definitely helps more than people think.
  6. I need help confirming a camshaft failure a 07 5.3 with DOD and flex fuel before I start tearing into the engine. I've been chasing a #5 dead misfire, gone through all the diag. and everything seems to be fine. Good plug, wire, coil, injector.. swapped all of those to #3 and misfire still on #5. No abnormal noise to speak of really, normal LS noise. Can disconnect #5 coil while running and can't notice a difference in sound like I do on all the other cylinders. HPTumers scanner shows #5 cylinder misfire counter going up steady. Now following some advice I've read from searching.. with the engine running (misfiring) and watching the misfire counter, I can back off #5 intake rocker about half turn and the misfire goes away. Tighten it back up and you can feel the engine misfire and watch the misfire counter go up immediately. I read this is the sign of a flat lobe on the camshaft. Can somebody confirm? I don't see a broken valve spring and the rocker seems to be moving fine just like the others. All rockers are tight and sound pretty normal. I know #5 is not a DOD cylinder but could still have a bad cam lobe / lifter I guess. Could an intake vacuum leak just on that cylinder cause this? I've sprayed brake clean around the area and didn't notice a change in rpm at all.
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