Knocking - Pre Ignition issue
#16
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You say that you went to the cat delete over a year ago and that there was no audible detonation as a result of the change. So, you can probably eliminate the test pipe as a direct cause.
I realize that itīll seem like a baby step, but why donīt you swap the stock DV back in place of the aftermarket piece, just to eliminate that as another possible cause.
I realize that itīll seem like a baby step, but why donīt you swap the stock DV back in place of the aftermarket piece, just to eliminate that as another possible cause.
Last edited by sparky; Jan 18, 2009 at 05:41 PM.
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That would be a surprise to me, and the only boost gauge i have is the stock gauge that comes with the MR. If it was a leak, would it not sound like a flutter (it would be associated with an "air" sound) or something similar to that? The "metallic" sound is what scares me.
But they can cause all kinds of drive ability issues that people will think its this or that and never do an actual proper leak test. Its the #1 test on my list when I am diagnosing an issue.....I like to get it out of the way because its cheap and easy to do.
You description of knock as metal sound certainly sounds right......I have heard it before in other cars and it sounds like marbles in a tin can rattling around. When you can hear it I would say its a pretty severe event.
#18
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You need to order a cable and log the car w/ evoscan.......if it is really knocking bad enough to hear you should see some pretty high counts in a log. That is the clear cut way to getting your answers for what/when/where questions to what is happening.....and the only way to prevent a catastrophic failure
#19
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You say that you went to the cat delete over a year ago and that there was no audble detonation as a result of the change. So, you can probably eliminate the test pipe as a direct cause.
I realize that itīll seem like a baby step, but why donīt you swap the stock DV back in place of the aftermarket piece, just to eliminate that as another possible cause.
I realize that itīll seem like a baby step, but why donīt you swap the stock DV back in place of the aftermarket piece, just to eliminate that as another possible cause.
#20
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Most times unless its a seriously huge leak you wont even know you have one without doing a proper test. A boost gauge will tell you nothing and you will never hear them in the car during driving, typically.
But they can cause all kinds of drive ability issues that people will think its this or that and never do an actual proper leak test. Its the #1 test on my list when I am diagnosing an issue.....I like to get it out of the way because its cheap and easy to do.
You description of knock as metal sound certainly sounds right......I have heard it before in other cars and it sounds like marbles in a tin can rattling around. When you can hear it I would say its a pretty severe event.
But they can cause all kinds of drive ability issues that people will think its this or that and never do an actual proper leak test. Its the #1 test on my list when I am diagnosing an issue.....I like to get it out of the way because its cheap and easy to do.
You description of knock as metal sound certainly sounds right......I have heard it before in other cars and it sounds like marbles in a tin can rattling around. When you can hear it I would say its a pretty severe event.
#21
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So the "knock" event is only happening at the transition into boost under normal driving loads and part throttle?........
Also.....reset the ecu when you get a chance before you drive it next.
Also.....reset the ecu when you get a chance before you drive it next.
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You are correct about the cable...there is no other way, and to be honest, with cars like ours, you HAVE to have it in your toolbox. As far as checking for a boost leak, how do you do that when the car ONLY does it under load? (acceleration)...I suppose I answered my own question...LOG LOG LOG (unless there is another way...?)
There should be a good how-to somewhere out there to give you more details - Google
http://www.vfaq.com/mods/ICtester.html
http://www.dsmtuners.com/forums/arti...et-tester.html
Last edited by travman; Jan 12, 2009 at 10:46 AM.
#23
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Yes, and it continues until i let go of the gas (to deccelerate); as far as the drive load...it happens in all drive loads, as long as i am into boost "range". I will reset the ecu, maybe the deleting of the CEL's that I have been performing periodically, has screwed something up.
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I am assuming that you have the stock boost control. But whatever. Check all of the boost hoses for tears, or leaks and assure that each hose end is secured to its respective nipple with a tight nylon ziptie.
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Have you taken off or modified any of the exhaust system near the turbo recently? Such as removing and reinstalling, the exhaust manifold, O2 sensor housing(or the sensor itself), or the DP, or the turbo itself. Does your car have the factory Anti-Lag system? If so have you loosened the two banjo bolt fittings for the ALS in the exhaust manifold?
Could be as others have mentioned a boost leak, or even a pre-O2 sensor exhaust leak which lets unmetered air into the exhaust stream and the ECU tries to correct for the unmetered air. Could also be a leak in the boost hoses going to the BCS(or MBC). Maybe even something funky with the knock detector circuit.
Could be as others have mentioned a boost leak, or even a pre-O2 sensor exhaust leak which lets unmetered air into the exhaust stream and the ECU tries to correct for the unmetered air. Could also be a leak in the boost hoses going to the BCS(or MBC). Maybe even something funky with the knock detector circuit.
Last edited by sparky; Jan 12, 2009 at 11:47 AM.
#26
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This is all good advice...I will check hoses, bolts and see what I come up with. I am going to kick myself in the head if it ends up being something stupid like that!
BTW, I have not moddified or moved ANY exhaust system component besides the cat...nothing else has been touced.
BTW, I have not moddified or moved ANY exhaust system component besides the cat...nothing else has been touced.
Last edited by Yorgis_MR; Jan 12, 2009 at 12:11 PM.
#27
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A boost leak would cause you to run rich as well as a pre o2 sensor leak. Not likely a cause for detonation.
How long have you been in Greece and are you sure its not 100 RON? Sounds like gasoline.
How long have you been in Greece and are you sure its not 100 RON? Sounds like gasoline.
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Imagine that your car was tuned spot on with perfect AFR's, and etc. Then your car's header develops a crack on one of the flange welds. Since the gases in your header are pulsating from positive pressure to vacuum...then unmetered air gets sucked in through the cracked weld.
The O2 sensor will read this unmetered air as a lean condition. So, the ECU will enrichen the fuel mixture. Now since fuel has been added...the O2 sensor will see a too rich condition and the ECU will begin to pull out fuel like crazy.
All of this lean condition and additional fuel has nothing to do with the actual amount of air which was measured by your MAF sensor. So the fuel mixture will be leaned out again by the ECU. This will swing back and forth between too rich and too lean Ad Infinitum. When it swings too lean.... the car will knock. That's how it is.
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I am talking closed loop/part throttle when the ECU compares the O2 values to the MAF values. The knock event would take place upon throttle tipin at about 3000 RPM on up. So, in the transition from partial to full throttle.