1 degree of knock I’m going

Andrew33

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so I started using my lund N gauge to monitor my car and I noticed that I was pulling 1 degree of timing when I went WOT.

Car is a 2012 GT500 with SW longtube headers/ catless h pipe, VMP 67mm throttle body, JLT 123, vmp pulley/idler combo, mantic clutch/flywheel and the plugs recommended by Lund gapped to his specifications. The gas being used is chevron 91 from California.

I sent Lund a email about it and he stated that it was a gas issue and not a tune issue. He recommended that I try octane booster. I put in a full can of Lucas octane booster and got new 91 gas and it’s still showing 1 degree in
KnockR on a 3rd gear pull and sometimes in second. It will start out at 0 in normal driving and when I go WOT it initially has a -knockR and then around 4400 RPMs it will climb up and stop at 1

I’ve read all the stock computer can pull is 1 degree max so I’m a bit concerned. I asked Lund and he says his tune will pull up to 3 degrees.

I’m going to Datalog the car and send it to Lund but I figured I’d check in here and see what you guys think.

I’ll probably put the car up tomorrow and check all my exhaust as well. Possibly the stage 8 header locking bolts or something hitting causing a false knock? I’m not really sure if it’s false or real and I don’t care to find out the hard way

Thanks,
Andrew

EDIT: please ignore the I'm going in the title. it should just be "1 degree of knock"
 
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Handlebar Moustache

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How many pounds of boost are you running? Is the KR being applied under high load/low rpm (WOT at the bottom of the gear)? I’m no tuner by any means, but I think 1 degree of KR here and there is not abnormal. Regardless, I’d go over the car and look for sources of false knock. I know you said you’re still getting the KR after the can of Lucas, but did that help it at all? If it helped a little... seems Lund would be right.


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Andrew33

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How many pounds of boost are you running? Is the KR being applied under high load/low rpm (WOT at the bottom of the gear)? I’m no tuner by any means, but I think 1 degree of KR here and there is not abnormal. Regardless, I’d go over the car and look for sources of false knock. I know you said you’re still getting the KR after the can of Lucas, but did that help it at all? If it helped a little... seems Lund would be right.


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I only have the factory boost gauge as a way to tell and I believe that’s pretty much pegged at 15. I’ll pay closer attention to it. It comes on at around 4400 in a WOT pull but not at below that. It did seem to get a little bit better with the Lucas
 

Handlebar Moustache

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I think basically the aftermarket tune is leaning on the knock sensors to run the timing as aggressively as it deems safe over the widest range of conditions.

If it seems like the Lucas helped a little, I'd do the following since these are cheap tests:

1) You said you put a tank of fresh fill, but did you change brands? Try filling up on a different brand of gasoline (use Chevron, Shell, Sunoco, or something name-brand and at a high-traffic, well-managed station).

2) Switch octane boosters and see if the car responds differently. Maybe try a can of Boostane.

3) See if the KR is worse when the car is hot / being driven on a hot day vs on a cool night/early morning. If so, that would indicate that it is not false knock and is fuel related.

Datalog with the NGauge, as you said. That is super handy...get the CSV files and plot them up in Excel...make some graphs. Take notes on environmental conditions when you datalog. Use the scientific method and you will eventually find the answer.

lol @PhoenixM3 meme
 

MastaAce03

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Throw the correct amount of Torco, Boostane or VP octanium in there. If it’s still reading knock, it’s false. How much timing is the tune commanding at WOT?


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Andrew33

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I Was searching for boostane and I remembered someone gave me 3-4 gallons of C16 a month ago. I think I’ll put that in and see what happens. I figure if it still does it with that it is probably false.
 

Catmonkey

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Have you logged the car to see what your timing is on a pull? If your gas is several weeks old, it's not going to have the same octane content as fresh gas. I know some don't drive that often and gas will deteriorate over time. Adding an octane booster is not going to work immediately either. You have gas in the fuel rail and the fuel lines and that additive has to mix in with the rest of the gas in the tank. But if you're still seeing only one degree of retard after the octane booster has had time to work, I'd be suspect of how much retard is plugged into that tune. You can also do a plug read and look for signs of detonation.
 

MelloStang2010

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Most likely false knock, I dealt with 3 degrees of knock ever since I started modding the car and showed up no matter what I did even blending in 2 gallons of 110 ocatane with my 91. Surprisingly what fixed it was a blower swap and motor mounts, probably the latter. The exhaust manifolds were touching something that was causing the knock sensors to pick up harmonics and the motor mounts gave me the clearance I needed I guess. Check to see how close your header primaries on the passenger side come to the ac bolt. There is a stud that sticks out towards the manifolds that can easily touch when the engine torques over under wot and cause false knock. Really stiff suspension can also cause it along with the MAF being loose and rattling against the air housing so maybe look into those things too.
 

Andrew33

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It might be real knock?

So I’m doing a max of 20 degrees timing when I’m at the end of a second gear pull. I noticed at 18 degrees timing that I was doing -1.0 on knock R. When it got to 19 degrees timing it started to climb .25 .50 .75 and then stopped at 1 degree knock R when it hit the max of 20 degrees timing.
 

Andrew33

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Most likely false knock, I dealt with 3 degrees of knock ever since I started modding the car and showed up no matter what I did even blending in 2 gallons of 110 ocatane with my 91. Surprisingly what fixed it was a blower swap and motor mounts, probably the latter. The exhaust manifolds were touching something that was causing the knock sensors to pick up harmonics and the motor mounts gave me the clearance I needed I guess. Check to see how close your header primaries on the passenger side come to the ac bolt. There is a stud that sticks out towards the manifolds that can easily touch when the engine torques over under wot and cause false knock. Really stiff suspension can also cause it along with the MAF being loose and rattling against the air housing so maybe look into those things too.

I’m going to put the car up in the air tomorrow and check everything out. Thank you
 

MastaAce03

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It might be real knock?

So I’m doing a max of 20 degrees timing when I’m at the end of a second gear pull. I noticed at 18 degrees timing that I was doing -1.0 on knock R. When it got to 19 degrees timing it started to climb .25 .50 .75 and then stopped at 1 degree knock R when it hit the max of 20 degrees timing.

20 degrees on 91 octane?


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Andrew33

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oh my. I've been driving it like this for probably 2500 miles with just 91 octane. I have been thinking about going to E85 as there are 3 gas stations that have it within 10 miles of me. This might just be the push to switch as I don't really want to start using a can of torco every tank. should probably just ask for my tune to be dialed back a bit instead of switching tho
 

me32

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It might be real knock?

So I’m doing a max of 20 degrees timing when I’m at the end of a second gear pull. I noticed at 18 degrees timing that I was doing -1.0 on knock R. When it got to 19 degrees timing it started to climb .25 .50 .75 and then stopped at 1 degree knock R when it hit the max of 20 degrees timing.
Thats too much timing on 91. 15-17 should be the range for ca 91.
 

me32

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I either need to dial it back a bit or go E85 and dial it forward a bit
You need to have 2 tunes. A conservative 91 ca gas tune with timing around 15-17 and then do E85 but make sure your fuel system is up to the task.

What all do you have done to the car?
 

Andrew33

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You need to have 2 tunes. A conservative 91 ca gas tune with timing around 15-17 and then do E85 but make sure your fuel system is up to the task.

What all do you have done to the car?

It is pretty stock so far. SW headers and catless H pipe, VMP 67mm throttle body, VMP upper and 90mm idler pulley, JLT 123, mantic twin disc clutch, MGW shifter.

I've been looking to buy a fore return fuel system and bigger injectors because I want to swap my blower out eventually. I feel like this might be a sign to do it

Id also switch from the lund gauge to a SCT and have shaun at AED tune it. He is within 2 hours from me so that is convenient. Id just use the N gauge as extra gauge
 

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