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Discussion Starter #1
Hi Guys,

I have a problem with a customer Jeep that I hope one of you may have a quick answer to.

Car was built by another shop but never ran right and now they got bankrupt, and the customer came to us.
Its a 2006 SRT with a very mild cam (268) a magnuson supercharger and a magnaflow highflow catted x-pipe.

The car runs and drives great, and I cant feel like there is anything wrong with it, but on my laptop I clearly see knock in a very specific rpm range (in between of 5000 en 5500rpm) pic attached

It has dual catch cans, there wassn't any real oil in the blower, I did a compression check, checked the knock sensors and retorqued them, checked if the exhaust wassnt banging anywhere etc etc, and am starting to get a little lost.

Sound familiar to anyone?
 

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Discussion Starter #3
Fuel looks good and we pulled almost all the timing to see if it would make it disappear.
I have the tuning done via a buddy of mine over email, there is a diablo trinity with the car, and I use dataviewer to log it
 

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Fuel looks good and we pulled almost all the timing to see if it would make it disappear.

I have the tuning done via a buddy of mine over email, there is a diablo trinity with the car, and I use dataviewer to log it


1 - Look at Lt KNK and ST KNK degrees not volts

2- How do you know fueling is good?

3- Post up base spark and actual spark


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Have you tried putting in race gas to see if the knock goes away?
 

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Discussion Starter #6
Thanks for thinking with me guys!

Unfortunately I have no acces to race fuel, but we use this gas in all the cars we work on, it has a higher octane rating than premium gas

1 - Look at Lt KNK and ST KNK degrees not volts

2- How do you know fueling is good?

3- Post up base spark and actual spark
1. Attached

2. I measure air fuel while driving

3. Also in the attachement
 

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Thanks for thinking with me guys!



Unfortunately I have no acces to race fuel, but we use this gas in all the cars we work on, it has a higher octane rating than premium gas







1. Attached



2. I measure air fuel while driving



3. Also in the attachement


1 degree of ST knk isn't bad since it is spiking and dropping down immediately.

Also please extend the legend down so I can see all of the colors for the graph.

Lastly, what is your AFR when the knock event occurs? I recommend you add that into the datalog because what you see on the gauge is usually the average of a few readings. The gauge refreshes at a slower rate then what you can see on the datalog. Additionally, you can add a little fuel which should slow down the flame front. I also need to see how much spark advance you are running that is why you need to pull down the legend.

Good luck! If you need any tune changes I recommend contacting a competent tuner like Joel


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Discussion Starter #8
Thanks, here you go.

afr is in between 11.3 / 11.5 above 5000rpm
I have the NGK AFR tool, I dont know if I can hook it up to the trinity, I didn't check that out yet
 

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Thanks, here you go.



afr is in between 11.3 / 11.5 above 5000rpm

I have the NGK AFR tool, I dont know if I can hook it up to the trinity, I didn't check that out yet


Try adding some more fuel in that range. You are barely running any timing. Has this occurred multiple times?


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Discussion Starter #10
We have tried adding fuel, and the timing wassn't always this low, we just pulled almost all of it to see if it would get rid of it, but it does it every time.

Someone said to me it might be valvetrain related, but I dont know, the cam is very mild, and I would also think it would do it from there to the end of the rpm range if it was for example the valve springs, and not this within in these specific 500rpms every time.....
 

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We have tried adding fuel, and the timing wassn't always this low, we just pulled almost all of it to see if it would get rid of it, but it does it every time.



Someone said to me it might be valvetrain related, but I dont know, the cam is very mild, and I would also think it would do it from there to the end of the rpm range if it was for example the valve springs, and not this within in these specific 500rpms every time.....


Could be just random noise then


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Well I wish there was a way to pin point it, because the customer also wants a smaller pulley lol

I personally wouldn't be concerned with it. The fact that it's an ultra quick spike and only 1 degree means it's very mild.


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Discussion Starter #14
my tuning knowledge is unfortunately very limited, my tuner says it is something to worry about. his reason is that anything over 3volts on the knock sensor is actual knock being detected, not just a noise coming from somewhere.
 

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my tuning knowledge is unfortunately very limited, my tuner says it is something to worry about. his reason is that anything over 3volts on the knock sensor is actual knock being detected, not just a noise coming from somewhere.


Well best of luck then!


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Discussion Starter #18
So I finally got to changing the valve springs and pushrods, but still the same problem.

Unfortunately Joel never replied to my emails, so I did not get to talk to him.

Anybody else able to chime in?
 
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