Knock Light Causes

[NOS-PRO]

TY member has Precision EFI that Thunder Products Clutching did the program for.

He had major knock issues and was cured by tightening the track

 

[cannondale27]

TY member has Precision EFI that Thunder Products Clutching did the program for.

He had major knock issues and was cured by tightening the track

OMG! Terry this is crazy.

 

[fullshift]

I had a chance to try my 290 tune. Its been very cold here lately and was -22C that day with about 6in fresh snow everywhere, it was nice and deep along tree lines. Have to say all 3 tunes start, idle,and run like they are factory fuel maps. This day we did 53 miles, top speed was around 100mph, very hard to see, everything was white and it was an overcast day. My 270 tune was turning 8600 rpm the last time out, so I didn't change set up, I was thinking that maybe the 290 tune could pull it to 8800, but it didn't. I was under revving so changed the 3/4 long inch set screw for 1/4 in my Dalton primary weights. Still using Husky 94 fuel with my rpm now about 8800, only seen knock light 2x after pinning it on long hard pulls along the tree line. I would go about 400 ft cat walking all the way, lots of fun. Probably did this 7-8 times. Both times when the light flashed it was right as I let off or right before I let off. I also heard small backfires a few times when I let off. I think the biggest difference between 290 and 270 tunes is the 290 builds rpms quicker. With the Husky 94 my white exhaust panel is a lot blacker and the guys following me on trail say it smells weird, like corn or maybe #*$&@ lol. Tried all 3 tunes that day no other knock lights. My sled seems to like the Husky 94 fuel.

 

[Crossfire12]

TY member has Precision EFI that Thunder Products Clutching did the program for.

He had major knock issues and was cured by tightening the track

Does anybody think that vibration from track would set off knock? I know a clutch will.

 

[cannondale27]

Does anybody think that vibration from track would set off knock? I know a clutch will.

It very well may but it should not. All sounds have specific frequencies. Thats why a knock SENSOR tune is so darn hard to perfect.

 

[STAIN]

It very well may but it should not. All sounds have specific frequencies. Thats why a knock SENSOR tune is so darn hard to perfect.

Cannondale, we have seen, at the Toyota dealership that I work at, running problems from badly chopped tires. They trigger the knock sensor and the timing gets beat back and the customer complains of a running problem. Of course cars/vans don't have a knock light, the ECU just responds to what it sees. Crazy but true.
The guy on the tech line had seen it before( running problem at higher speed) and suggested swapping tires. We thought he was crazy until we swapped out wheels and tires from a new car, problem cured. New tires and alignment sold!!!!
We haven't seen it for a few years though and it was only on a couple of models with the same engine/trans package, so they may have adjusted the parameters on that circuit. Just saying it is possible.
Also, I have a Hurricane SMT and I always run it on 270 and have NEVER seen a knock light.
Are those sleds heavily studded? More than 3 per bar?

 

[cannondale27]

Cannondale, we have seen, at the Toyota dealership that I work at, running problems from badly chopped tires. They trigger the knock sensor and the timing gets beat back and the customer complains of a running problem. Of course cars/vans don't have a knock light, the ECU just responds to what it sees. Crazy but true.
The guy on the tech line had seen it before( running problem at higher speed) and suggested swapping tires. We thought he was crazy until we swapped out wheels and tires from a new car, problem cured. New tires and alignment sold!!!!
We haven't seen it for a few years though and it was only on a couple of models with the same engine/trans package, so they may have adjusted the parameters on that circuit. Just saying it is possible.
Also, I have a Hurricane SMT and I always run it on 270 and have NEVER seen a knock light.
Are those sleds heavily studded? More than 3 per bar?

Yes both are studded. One for drag racing and other just up middle.

 

[SledFreak]

Bringing this back to the top... So what is the consensus of this post... Boost leaks were causing the knock detection?

 

[no1b4me]

Bringing this back to the top... So what is the consensus of this post... Boost leaks were causing the knock detection?

IMO.....for what I have experienced and compared to a few factors ....for my situation is YES.....though for other situations there may be other underlying factors involved causing the knock light....most common=leak...IMO

 

[eightpilot]

Mine was a faulty knock sensor.... Never saw the light again unless i leaned out my regulator too much.

 

[fatchance]

I had a boost leak that caused boost spikes and triggered the knock sensor.

 

[SledFreak]

Thats seems to be what has caused knocks that I have read about... Also, the post that Hurricane posted in Jan or Fed of last winter where he indicated that boost leaks were causing knock sensor to activate, mostly under big power tunes and it was activated by the intake clamps not being tight enough.. That is something, I am going to make sure that there are no boost leaks when I add a tune..

 

[yamamarc]

Thats seems to be what has caused knocks that I have read about... Also, the post that Hurricane posted in Jan or Fed of last winter where he indicated that boost leaks were causing knock sensor to activate, mostly under big power tunes and it was activated by the intake clamps not being tight enough.. That is something, I am going to make sure that there are no boost leaks when I add a tune..

Even check for leaks annually it crazy the amount of sleds have loose clamps!!
Very easy to make with about 20-25 $ of stuff from Canadian tire

 

[jonlafon1]

I wonder if a weak fuel pump would cause a knock ?? Just a thought of mine.

 

[Turboflash]

I worked on one 280 tuned sled where knock light got triggered by loose track. Stud heads were banging against outer end of front cross shaft (that mounts rail to tunnel) so hard it triggered knock light.