3.8 pinging
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JK Enthusiast
Joined: Dec 2009
Posts: 384
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From: Canada
Originally Posted by Ryan0260
Well if they have seen a few motors with the same problem then how did they fix them? Sounds like they are playing cat and mouse. I would drop it back off and tell them to call you when it is actually fixed...
JK Junkie
Joined: Jul 2008
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From: Lakewood, OH
The system relies mostly on TPS and crank position on a speed density system. Once the MAP no longer reads vacuum, it is no longer part of the equation (unless it is in a boosted application). Even still, once a knock event is detected, it will still pull timing out until it is safe again. The problem the OP is having is that his pre-ignition problems are persistent and it is unlikely carbon is the culprit here. What is logical at this point is the PCM is not managing timing like it should. The knock sensor should be trimming values as needed and either the system is not functioning properly or the increased airflow you pointed out is seriously throwing the PCM out of whack, which is unlikely as many have run a CAI on this rig with no additional tuning and it works out just fine. As a matter of fact Diablosport does not have a CAI tune for the JK because they said it did not need one as the CAI did not throw the JKs tune out of whack so this means that a CAI probably does not flow that much more than a stock setup or Diablosport is feeding me misinformation.
Surprisingly enough the dealer did not do any diagnostics to see if the PCM is logging knock events? Gee whiz cars will practically talk to you with the kind of stuff OBDII will tell you these days. God only knows what we had to do prior to cars marrying computers.
Surprisingly enough the dealer did not do any diagnostics to see if the PCM is logging knock events? Gee whiz cars will practically talk to you with the kind of stuff OBDII will tell you these days. God only knows what we had to do prior to cars marrying computers.
My personal issues with a lean condition was remedied nearly 3 years ago. Blistered white plugs which in my case I believe was attributable to shorty headers and my former programmer. My first big swing at it found remedy, slightly colder plugs and a bump in octane. My thought at the time was it was detonation induced pre-ignition, and right or wrong my issues were gone. A new programmer, back to original heat range plugs and the issue hasn't arisen again.
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Joined: Jun 2011
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From: Hendersonville, Tennessee
Originally Posted by itsajeepthing91
Like I said they are being good about it all of this is under warranty all they asked of me is to try two tanks of fuel and than they would pull the heads.
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JK Enthusiast
Joined: Dec 2009
Posts: 384
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From: Canada
Pinging seems to be getting better might just be in my head. I would have thought that the results of the flush would have been fairly immediate after flush maybe not. Hopefully I'm not getting excited for nothing we will see. My biggest concern at this point is how much damage has been done to the motor already from the on going pinging.
Super Moderator
Joined: Jun 2011
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From: Hendersonville, Tennessee
Originally Posted by itsajeepthing91
Pinging seems to be getting better might just be in my head. I would have thought that the results of the flush would have been fairly immediate after flush maybe not. Hopefully I'm not getting excited for nothing we will see. My biggest concern at this point is how much damage has been done to the motor already from the on going pinging.
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JK Enthusiast
Joined: Dec 2009
Posts: 384
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From: Canada
Originally Posted by bubba_zenetti
Well that is why I do not think it is pinging. Pre-ignition will damage a motor in very little time. Usually in the form of a hole melted right into the piston. Detonation will simply crack ring lands, erode the piston top and overheat the motor to the point where piston skirts will start scuffing. All this in very little time. There is no way you can drive around for months having a condition like this or your motor would be pretty banged up by now. And for certain there would be signs of knock on the spark plugs in the form of blistering and melted electrodes.
Any form of detonation or pre-igniton will always be followed by a loss of power and even more pinging noises as the load is increased. If you step on the gas and it pings then step on it harder it will ping harder not go away.
If this truly is the work of excessive carbon buildup, there would be no more knock after it was flushed, that is provided that it actually worked because very few so called flushes just do not work.
If it were me, I would be going to a different dealer. Pouring in snake oil and calling it a say when I read between the lines is telling me that they do not know what is wrong with it get it out of here and move on to the next project.
Like I said, cars will tell you what is wrong with them these days. All you need is a good diagnostic scanner and a good tech behind it. Which at this point if you really feel it is knocking, that is what I would be doing. Yep carbon might be a precursor to it by why is your engine management system not doing its job?
BTW have you tried putting your stock air box back on and see what that does? It may be your engine management is not dealing with the additional airflow from your CAI. Honestly a lot of people run them with stock tuning just fine as they tend not to flow that much more than a stock setup but who knows, you may be a freak case of CAI not agreeing with PCM.
Unfortunately I sold my stock airbox so I can't give it a try.
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Joined: Jun 2011
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From: Hendersonville, Tennessee
Bubba how is the BG44k used? Do you run it through a vacuum line and if so I'm assuming you need to keep the rpms high to keep the engine running. I may try the Chrysler combustion cleaner first, compliments of a friend at the stealership
JK Enthusiast
Joined: Apr 2009
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From: atlanta
BG 44K® Power Enhancer®
BG 44K® Power Enhancer® safely, rapidly and thoroughly removes engine deposits in combustion chambers, intake manifolds, ports and on valves. It restores flow in fuel injectors and cleans the entire fuel system. BG 44K® Power Enhancer® improves fuel economy and reduces exhaust emissions. It restores that “like new” driveability to an engine’s performance and keeps it running better, longer and more efficiently. Add one can or bottle to fuel tank at fill up. Catalytic converter and oxygen sensor safe.
JK Enthusiast
Joined: Apr 2009
Posts: 233
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From: atlanta
What exactly are they going to pull the heads for? What will that prove or disprove or solve? Do they think they need to chisel out the carbon? I would want to know what pulling the heads is going to accomplish. That seems pretty drastic for a next step. And if you really want to test the airbox theory, I have one you could borrow, provided you pay the shipping both ways........which I know is not cheap, but thought I would at least offer.