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decelerating at high rpms..smoke issue

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Old Oct 25, 2010 | 01:30 AM
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Question decelerating at high rpms..smoke issue

Was driving,& i noticed in 3rd gear and 4th at 6 to 7k rpm's of course high speeds i am spraying blueish smoke from out the exhaust only when i decelerate....My last tunner disconnected the catch can and took off a resonator that comes off the headers so i am running straight pipes to my Borla mufflers on my vette...no smoke on acceleration just when i take it up to say 7k then let off the gas any suggestions or link to this problem..thanks
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Old Oct 25, 2010 | 04:11 AM
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are you sure its the exhaust? could be a normal no cats smoke.
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Old Oct 25, 2010 | 09:13 AM
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Question deceleration smoke

Originally Posted by omarrakeen
are you sure its the exhaust? could be a normal no cats smoke.
I have been running catless for 5yrs...and no problem till lately...My last oil change it seemed to have started and is now progressing....wondering the pure synthetic 10w/30 could be causing it....thinking about going back to conventional Penzoil 10w/30.....
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Old Oct 25, 2010 | 08:51 PM
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I'm guessing you have an LS1 Corvette? If that's the case your just seeing the crappy LS1 PCV system in action. I road race my LS1 trans am and have delt with that for the past few years. I can get it to the point that people come up to me after a session and ask me if I blew my motor. An oil catch can/seperator will help but not fix the problem. There is a good write up on LS1howto about switching over to the LS6 PCV system. That's going to be the only real way to fix the issue. It's not going to matter what type of oil, but if you use a thicker weight it will smoke a little less. The only thing it's affecting right now is you spark plugs. So don't worry too much. You'll learn to ignore it.
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Old Oct 25, 2010 | 11:23 PM
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Originally Posted by kmspruill242
I'm guessing you have an LS1 Corvette? If that's the case your just seeing the crappy LS1 PCV system in action. I road race my LS1 trans am and have delt with that for the past few years. I can get it to the point that people come up to me after a session and ask me if I blew my motor. An oil catch can/seperator will help but not fix the problem. There is a good write up on LS1howto about switching over to the LS6 PCV system. That's going to be the only real way to fix the issue. It's not going to matter what type of oil, but if you use a thicker weight it will smoke a little less. The only thing it's affecting right now is you spark plugs. So don't worry too much. You'll learn to ignore it.
i do have an LS-1 99vette...but with LS-6 heads with a big h/c pkg. not sure if i have the pcv LS-6 setup or not... I'll do another SEARCH for the LS6 pcv system..thanks
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Old Oct 27, 2010 | 03:28 PM
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I have the same thing happen to me.. Chances are, like me, you have worn valve seals
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Old Oct 27, 2010 | 10:00 PM
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Worn (intake mostly) valve seals are usually the cause of startup puffs of smoke, and decel smoke. When you close the throttle at high rpm's, theres a lot of vacuum created in the intake tract, and pulls hard on the valve seals as well, sucks some oil, and presta - smoke machine!

Oil causes detonation, so stopping your engine from burning it should be a priority.

The ls6 pcv is a great idea for these engines, with how isolated the "lifter valley" is from moving/rotating parts coming in contact with oil.
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Old Oct 28, 2010 | 07:35 AM
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X3 on the seals. If you have ported heads, seal the rocker bolts with locktite.
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