Pro SCT tuners: Knock sensors reading very high values 80-120 at idle?

[Denver_SVT]

I need help from Pro SCT tuners as I'm in the process of tuning this 2010 Roush 427R pump gas 95 and found out there is a very high knock value from Knock Sensor 1 & 2 at idle and partial throttle. After we upgraded the SC pulley with small one the knock sensor become very sensitive and reading from data log at idle around 80 in B1 and 120 in B2 and at partial throttle will read much higher above 200 to 400*

Do you think this is a false knock or real from your experience? I don't hear any knock/rattle from engine at all during idle and partial throttle. from borderline knock table I reduces the timing very low to 12* from 3500 to 6500 on the load 0.600 and above. We also added Torco octane booster to see if knock values will reduce but still no change at all. I can play with the knock sensitivity but this will be last option to reduce the numbers 20-30%

Note: at idle when we open the hood we heard some tik tik little noise from the side of the heads like a rockers sound but not sure if that normal or not. the owner said it's normal but for me it doesn't sound normal at all and I thought maybe that will affect the knock sensors to read very high.
any help will be appreciated.


any suggest will be appreciated.

 

[decipha]

well yeah any mechanical noises will make the knock sensors go ape shit even adding long tube headers that 'tick' in with that 'hollow piping' sounds is enough to cause them to act up.

Take the blower belt off and let it idle, see what the knock sensors say and if its no better then u need to isolate that noise your hearing and fix it.

 

[Denver_SVT]

well yeah any mechanical noises will make the knock sensors go ape shit even adding long tube headers that 'tick' in with that 'hollow piping' sounds is enough to cause them to act up.

Take the blower belt off and let it idle, see what the knock sensors say and if its no better then u need to isolate that noise your hearing and fix it.

Thanks decipha for your usual support. How long to keep it running? You think 2 mins enough as the care will overheat because of the water pupm? Is it safe?

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[Denver_SVT]

and for your info the ROUSH 427R already have a hollow piping from the manufacture as only pipies going from headers with catalytic converter and then piping all the way back to the tips without any mufflers. Is it making sense to you now.

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[Denver_SVT]

well yeah any mechanical noises will make the knock sensors go ape shit even adding long tube headers that 'tick' in with that 'hollow piping' sounds is enough to cause them to act up.

Take the blower belt off and let it idle, see what the knock sensors say and if its no better then u need to isolate that noise your hearing and fix it.

Hello decipha, we took the blower belt off and run the car at idle and we still have knocks reading much higher than before around 1000's.

This issue driving us crazy if it's real knock of false.

Any advice of troubleshooting the issue more deeper, it will be very appreciated.


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[Denver_SVT]

Just an update, we open the valve cover to make sure rockers are ok and they looks good, then we did a compression test of all 8 cylinders and all reading goods (210 psi) in each cylinder. We did leak down test and no issue all witin specs nothing more than 12% of leak. We checked headers and exhaust and looks ok with zero sign of issue.

Our last troubleshooting will be changing the knock sensors and see if that will fix the issue. It seems not a real knock, its false i guess.

If after changing the knock sensors and still reading knocks; do you think our option to disable the knock from the sct software or it will be risky?


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[gt347mustang]

Sounds like the noise is coming from the timing chain area? Why not fix the noise first. Replacing overly active knock sensors when you can audible hear noise seems backwards to me.

Are you in Denver?

 

[Denver_SVT]

Sounds like the noise is coming from the timing chain area? Why not fix the noise first. Replacing overly active knock sensors when you can audible hear noise seems backwards to me.

Are you in Denver?

We thought about it and list it in our troubleshooting steps but we decided to not check it as there is no noticeable noise from it at all.

So, should we check it before we change the knock sensors or first change the knock sensors and see from there.?

If the knock sensors bad isn't going to send a code to the pcm?

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[Denver_SVT]

I use to live in Denver a while ago.

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[decipha]

if you cant get the knock sensors to function correctly then your only option is to disable them

no risk as long as you trust your tuning abilities

 

[BigPoppa]

Knock sensors don't usually set a code if the crystal is bad, just the loop.

It isn't uncommon for a positive displacement blower to create false knock, especially as the blower ages and the bearings get more wear.

It isn't too hard to swap the knock sensors, so that is what I would do. If the knock is still present, go from there.

 

[Denver_SVT]

we tested the Knock sensors out of the car with Volte-meter and they work fine. So, we decide not to change them and move from there. Our last option in the troubleshooting to change the cam phaser. So, We ordered Comp cams Phaser limiter to install and see if it will fix the noise issue during data log. defiantly we will adjust the VCT tables on the tune for the new cam phaser to get benefit from it. If the issue still there we will disable the knock sensors from the SCT advantage software as we tried everything and we don't have any option. I will keep you posted.

 

[Denver_SVT]

New update of our troubleshooting, after we changed the comp cam phaser we did idle data log and the knock sensor bank 1 & 2 still occur with same reading 90-110.

So, I think it's fault reading and our last option is to disable the knock sensors from the software since we tried everything. Do you agree with me guys of the disable idea?

 

[mizlplix]

You are just discovering what the Ford engineers found out with the Gen 2 Lightnings. They had to disable the knock sensors. Blower and other noises being read as knock. They had to do a last minute tune on all of them after assembly. Each was slightly different.
If you are concerned about knock, get a Vampire. The best engine saver ever made.

 

[Denver_SVT]

You are just discovering what the Ford engineers found out with the Gen 2 Lightnings. They had to disable the knock sensors. Blower and other noises being read as knock. They had to do a last minute tune on all of them after assembly. Each was slightly different.
If you are concerned about knock, get a Vampire. The best engine saver ever made.

Thanks for the advice. Really appreciate it.

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[Denver_SVT]

Final update:

We disabled the knock sensors from the tune and tuned the car with no issue at all. The car runs like a champ and feels very strong.

I would like to thanks everyone for the kind support and many thanks for Decipha.

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[decipha]

cool

how much boost did it make? rwhp? how much timing did u settle on?

 

[Denver_SVT]

With VMP 2.49" supercharger pulley and 90mm Idler pulley the car pushed with 7-8 pounds of boost and when it get wormed it pushed only 6 psi which is an indication of belt slip because we noticed that from the boost gauge and Load reading from the datalog as it went from 1.4 load and dropped to 1.280 . The air flow #/min 38,000

We ordered the smaller belt than the stock roush belt within 0.197 inch differences (Old belt size 132..638" and new belt size 132.441" ) and hopefully it will fix the slippage. we tuned it at the street and we will take it to the dyno once we replace the belt. we give the car 15 degrees of timing. we have a snow performance methanol installed that we will turn it on at the dyno to give the car extra 2 degrees of timing. I will post the dyno numbers soon.