3.8 pinging
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JK Enthusiast
Joined: Dec 2009
Posts: 384
Likes: 1
From: Canada
Originally Posted by bubba_zenetti
Changing your oil is not going to solve pinging. Neither is putting in spark plugs that are colder. They do not ping with normal heat range plugs so if you are indeed preigniting, you have a serious issue and solving it with a spark plug one step colder is not going to do anything. Nor is chagning your knock sensor. A knock sensor is there to pull timing out when it detects knock. Your PVC valve vents the crankcase it has nothing to do with preigntion problems.
A stock JK should be able to run 87 octane fuel without any preignition. Things that cause preigntion are hot spots in the combustion chamber, excessively lean fuel mixtures or incorrect ignition timing. If its not throwing any codes, chances are there is nothing wrong.
I am willing to bet that you have an exhaust leak on the drivers side manifold. They crack there very often. The sound of it can be confused for preignition. When the exhaust gets hot enough the crack will seal from heat expansion making the sound come and go. Pull the heat shield off it and have a look. On them things its not a matter of if it will crack, its when it will crack. Yours probably has one in it.
A stock JK should be able to run 87 octane fuel without any preignition. Things that cause preigntion are hot spots in the combustion chamber, excessively lean fuel mixtures or incorrect ignition timing. If its not throwing any codes, chances are there is nothing wrong.
I am willing to bet that you have an exhaust leak on the drivers side manifold. They crack there very often. The sound of it can be confused for preignition. When the exhaust gets hot enough the crack will seal from heat expansion making the sound come and go. Pull the heat shield off it and have a look. On them things its not a matter of if it will crack, its when it will crack. Yours probably has one in it.
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Joined: Jun 2011
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From: Hendersonville, Tennessee
Originally Posted by itsajeepthing91
But why would the sound go away with higher octane if it was exhaust manifold?
Thread Starter
JK Enthusiast
Joined: Dec 2009
Posts: 384
Likes: 1
From: Canada
Originally Posted by Ryan0260
Because its not an exhaust leak. An exhaust leak is noticeably different in sound and doesn't go away different fuels. And the guy above is wrong. If a motor has faulty rings a thinner oil will will allow more blowby causing fouling of the plugs which can cause detonation and pinging. Same with a clogged pcv valve which will will also cause fouling of the plugs
JK Newbie
Joined: Mar 2011
Posts: 19
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From: Bangor, ME
Because its not an exhaust leak. An exhaust leak is noticeably different in sound and doesn't go away different fuels. And the guy above is wrong. If a motor has faulty rings a thinner oil will will allow more blowby causing fouling of the plugs which can cause detonation and pinging. Same with a clogged pcv valve which will will also cause fouling of the plugs
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Joined: Jun 2011
Posts: 11,054
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From: Hendersonville, Tennessee
Originally Posted by zack3A/E
He is not wrong at all...you can type "jeep 3.8 pinging" into google and it come up with a cracked manifold fairly quickly...they sand almost identical
