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Author
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Topic: Help with spark knock issue
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alexv
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Member # 13018
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posted
 
 
So I have a 96 Cobra, I recently changed the fuel filter, spark plugs and rear gears (I also have a SCT tune from Bama).
Recently I started noticing a rattle coming from under the dash; I didn't pay too much attention as I thought it was just the dash itself (the plastic trims) rattling. But this morning I took a bunch of small pieces of cardboard and put them between the trims to make sure there was no play in the dash.
But no, it doesn't seem like this was the problem and now it has become clear that the noise is coming from the engine bay. It sounds like an interference coming from a speaker (that little sparkling/ rattling noise) except it's coming from the engine.
It doesn't happen when in Neutral; only when driving AND going over 3000 RPMs.
I am thinking it is spark knock, but I don't know for sure.
The spark plugs that were replaced where OEM sparks, the new ones are NGK V-power performance 3951
What should I do? Replace the sparks again or make a data log and contact Bama for a new tune?
Right now, I reverted back to stock tune and I just bought some octane booster to see if that helps.
Posts: 119 | From: Novato, CA | Registered: Jun 2013
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SacStangDriver
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Member # 8304
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posted
how does it run on stock tune? same problem?
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Need sidework done at great prices? I work on all makes and models from engine work to gears. Check engine light problems too. 916 912 3493
Posts: 1217 | From: sacramento | Registered: Mar 2008
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alexv
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Member # 13018
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posted
Yeah, no difference with the stock tune, and I am going to try the octane booster tomorrow.
[ 2013-09-16, 11:22 PM: Message edited by: alexv ]
Posts: 119 | From: Novato, CA | Registered: Jun 2013
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SacStangDriver
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Member # 8304
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posted
that probably wont do anything
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Need sidework done at great prices? I work on all makes and models from engine work to gears. Check engine light problems too. 916 912 3493
Posts: 1217 | From: sacramento | Registered: Mar 2008
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alexv
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Member # 13018
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posted
Crap ;/ It was a shot in the dark, really...
What should I do?
Posts: 119 | From: Novato, CA | Registered: Jun 2013
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Tom Renzo
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Member # 13165
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posted
First thing is what octane are you using?? And is the knock sensors working properly. (do you have an SES LIGHT?). Also is the EGR valve working properly and flowing correctly? That engine should not knock as it is controlled by a knock sensor to prevent that. So you have to see if they are working. And check the rate of retard under knock conditions. But if your stock tune is in place that should not be an issue.Are you sure it is an octane ping!!
In your area what is the highest octane fuel available?? And what octane are you using?? If you can go up in Octane do this to confirm it is an octane knock. By uppng octane numbers and the condition goes away you know your issue. If increasing the octane does not do it then you have to find out what is going on. I personally do not use octane boosters as we have 106 available in our area. Good luck!
[ 2013-09-17, 02:24 AM: Message edited by: Tom Renzo ]
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I spend money i don't have. Building cars i don't need. To impress people i don't know.
Posts: 557 | From: CT | Registered: Sep 2013
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alexv
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Member # 13018
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posted
The highest Octane available here is 91 and that's the one I have always been using. I do not know for sure if it's an octane knock or not.
I do not have a check engine light or any DTC code that I can see by using a SCT tuner.
I'll data log asap to see if I can get any more data that would be useful (I don't have a laptop so I need to borrow one from a friend to do it).
I'm not sure how to check if the EGR is working fine or not. It doesn't look like I can data log that.
Thanks for the help!!
Posts: 119 | From: Novato, CA | Registered: Jun 2013
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Wht86drop
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Member # 12104
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posted
Try and find a 76 station thst has 100 octane at the pump. The handle is blue
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Jalapeña Red 86 GT Vert
Yellow 72 Chevelle
Rio Red 97 Cobra
High-Output Generations CC
Posts: 1669 | From: East Palo Alto, Fiji Islands | Registered: Jun 2012
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alexv
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Member # 13018
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posted
The octane booster didn't do anything. I may try to find a 100 octane this week end, but it doesn't seem like it would do much either.
Posts: 119 | From: Novato, CA | Registered: Jun 2013
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Tom Renzo
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Member # 13165
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posted
If boosting the octane does not work you have other issues.
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I spend money i don't have. Building cars i don't need. To impress people i don't know.
Posts: 557 | From: CT | Registered: Sep 2013
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