Turning off Knock sensors

[o2sys]

Anyone here running their mild to heavily modified engines with their knock sensors turned off? Coming this far with your build especially with FI, are they as effective as it was when stock?

I've been battling spark knock ever since I installed my Paxton 2200 H.O. when I'm at WOT only.

It's a JDM 302 Stroker (3.8" crank, .010 Over bore).

Took the necessary steps to verify the knock was possibly false:

1. Reduce timing
2. Run Torco
3. New plugs with proper gaps

Every time I log I get spark knock only at WOT, it pulls timing gradually until it's -5 and I let go of the throttle. Otherwise nothing through out the rev range.

Car is too loud to hear any possible knocking with my ears, checked the plugs multiple times and have no signs of detonations either.

So finally decided to turn off the knock sensors and still don't hear anything. Did couple of WOT pulls but nothing like pinging or knocking sounds.

The tune with ks turned off was made so I could hit the dyno to get some numbers and show off lol (jkjk) but just wanted to know how many of you guys have them turned off for every day driving or for the track only.

 

[redfirepearlgt]

Nope, my tuner keeps knock sensor active. Most i know tuning street driven 3V's or Coyotes do. It's a great technology. My tune limits the KS strategy to only add up to 2 degrees of timing in optimal condition (total 18 degrees WOT). It can pull as much as needed if things like IAT2 temps sky rocket, or bad fuel is detected in the lines, etc.

 

[o2sys]

Is your coyote motor built or stroked?

 

[weather man]

Won't be any knock sensors on my 3V at 1,000 HP.

 

[stkjock]

IIRC - stroker builds are known to give false knock readings, piston slap also contributes to false readings

 

[o2sys]

IIRC - stroker builds are known to give false knock readings, piston slap also contributes to false readings

That's what I've been reading as well. But wondering who runs them off because of this.

There some short discussions about all the Saleen 302 strokers having this issue but never mentioned of turning them off or on.

 

[stkjock]

did you search and find these:

http://s197forum.com/forum/showthread.php?t=90147&highlight=knock+sensors

http://s197forum.com/forum/showthread.php?t=28847&highlight=knock+sensors

 

[redfirepearlgt]

Is your coyote motor built or stroked?

NO sir. Just a simple 302 Coyote running 9-9.5psi FI, which I would classify as "mildly modified".

I texted a friend with a wild setup very similar to yours. Its a 3V forged.stroked/cammed/and running Procharger F1A at 20psi and putting 725+ to the ground on corn. He should be able to tell me if his is running knock sensors or not. Maybe that will help you. I know Lund tuned his car. I also know he has IAT2 temp issues at the track he is trying to over come which causes the tune to pull a ton of timing. So when I hear back from him I will let you know what he has got going on. He is in the process of going meth injection to get the IAT2 temps down. Massive aftermarket Air-Air heat exchanger upgrade helped but wasn't enough. He even pullied down back up 22 to 20psi and still fighting the issue.

Maybe this 411 when he responds will be of more help to you.

 

[o2sys]

I have zero issues with IAT with the Paxton intercooled. With blow thru I'm able to see the iat the maf is seeing and it's always at ambient temp and even if it's heat soaked it goes right down to ambient again.

If your motor is still stock the KS are probably still very functional.

 

[redfirepearlgt]

I have zero issues with IAT with the Paxton intercooled. With blow thru I'm able to see the iat the maf is seeing and it's always at ambient temp and even if it's heat soaked it goes right down to ambient again.

If your motor is still stock the KS are probably still very functional.

That is a good thing for you. I doubt that you did being you are running a Paxton setup. The Paxton and Vortech seem to be a lot more friendly in that aspect.

He just called. He is bored .020" over but not stroked. All forged internals. Custom blower grind Comp Cams with phase limiters. 20psi as stated on the F1A and he said that Lund is using the knock sensors. Now that said, he's only at 284CID on that engine so stroker wise it is nothing aside from the cylinder work and of course forged rotating assembly. You might just contact Ken B at Palm Beach Dyno and ask him, or email LUnd and see if they use knock sensors effectively on a full stroker setup like yours. Sorry I could not have been of more help.

 

[o2sys]

Seems like JDM also turns them off on their tunes for this type of setup.

Now if they were on and let's say real knock was really detected is it fast enough to prevent damage or in FI it's too late anyways?

 

[01yellerCobra]

What about going to an aftermarket set up?

http://www.jandssafeguard.com/VampirePage/Vampire.html

 

[redfirepearlgt]

Seems like JDM also turns them off on their tunes for this type of setup.

Now if they were on and let's say real knock was really detected is it fast enough to prevent damage or in FI it's too late anyways?

That's a good question. I don't know. I assume Ford is using them on the 13-14 GT500 5.8L FI engine. How far that technology could go probably depends as much on the scan time of the PCM in responding to retard timing fast enough given the detonation condition, as well as the functionality of the knock sensor itself which is not a cheap item from what I understand. how far it can go to protect my Coyote setup as well IDK. But its pretty impressive what it can do compared to just the early 90's fox body cars.

 

[fdjizm]

Won't be any knock sensors on my 3V at 1,000 HP.

Your warranty is sooooooooooooooooooooooo void bruh!

 

[BruceH]

I've always kept them active. All of my motors have been stock stroke except for the current one.

The current motor will pull spark when running gasoline from some stations but it never pulls it with E85. To me this means the sensors are doing exactly what they are intended to do.

Keep in mind that more than just the knock sensors will pull spark advance. There are inputs for the iat, ect, and something else that I can't think of right now.

In any case running wot with -5 total spark advance is a good way to burn your motor up. More than likely your exhaust is glowing red at that point, good thing Ford uses Inconel exhaust valves because I think -5 would burn up any other material like stainless steel.

 

[o2sys]

I understood as the spark ks source showing negative value is the ecu pulling timing because it detects knock. Not advancing timing.

 

[o2sys]

What about going to an aftermarket set up?

http://www.jandssafeguard.com/VampirePage/Vampire.html

Sounds expensive, doesn't list a price.

 

[BruceH]

I understood as the spark ks source showing negative value is the ecu pulling timing because it detects knock. Not advancing timing.

Maybe I read it wrong? I was reading that your total spark advance at wot was -5. The lower the spark advance the hotter the exhaust. That is what I was getting at, if too much spark is being pulled you will have high exhaust temps.

If I have it wrong then what are the spark advance readings at wot throughout the rpm range?

 

[o2sys]

Spark advance is around 12, spark source is at 2, spark ks -5, Tp relative 600

 

[Born To Run]

Knock sensors

I removed mine physically form the stock longblock.
Locked timing at 20 degrees.
I seen some Air inlet temps spike at the 1200' mark in the 200F range & beyond.
FI running 12-15 psi & beyond in some cooler air.
Had a tune when I got in trouble wth 25 degrees of timing.
I made it once to the semi finals in the NMRA with a piston skirt failure occurring from the 2nd round of qualifying.It was knocking so bad the guy in the other lane thought it was his car,haha.
Won the race in the semis as Bowles red lit,but I blew the motor at the 1/8 mile mark at 100 mph in 7.0 seconds.
Car is now on the road,still with no knock sensors,don't buy shitty low octane gas & you will be fine.