Par throttle Knock and transition knock?

blackshoebox

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Aug 20, 2001
I just happen to be zipping home on the highway tonight when i noticed when i par throttle the car, i would get a small amout of knock(>3%). What could be the cause of this? Could a correction be gapping the plugs tighter(mine are gapped at 35) or change the ones im running(ac43's)? Or maybe richin the mixture up a little bit? im running the 009's with the red93 chip, with the smc alky, along with all the typical bolt on's. I also have been getting some transition knock since running the alky kit, and wonder if the two could be related and maybe if i figured out how to correct one, it will correct the other.

Any advice would be appreciated. Keep in mind the im only getting very small amounts (>3 percent) but want to tune the car for street trim, with alky to run all through the gears with NO knock(maybe just a hair on the shift) which is normal.

Shoebox
 
Blackshoebox, does the knock occur at a certain rpm (possibly at a natural frequency similar to the exhaust drone) or only under boost conditions (due to increased load, torque, or engine twist)? Is it consistent or intermittent? Does changing the alky pump speed have any effect? Does it occur just by increasing rpm without going into boost? I'm not sure about the spark plug gap but that would be easy enough to test. If you recently installed the alky kit maybe you just need to drive around a little more to let the cells learn in. I've seen old motor mount safety hooks metal out on the driver's side and cause this. I don't think its the chip or injectors. Please let us know when you find out what the problem was. Good luck, Joel
 
Re: Re: Par throttle Knock and transition knock?

Originally posted by TurboGN
Blackshoebox, does the knock occur at a certain rpm (possibly at a natural frequency similar to the exhaust drone) or only under boost conditions (due to increased load, torque, or engine twist)? Is it consistent or intermittent? Does changing the alky pump speed have any effect? Does it occur just by increasing rpm without going into boost? I'm not sure about the spark plug gap but that would be easy enough to test. If you recently installed the alky kit maybe you just need to drive around a little more to let the cells learn in. I've seen old motor mount safety hooks metal out on the driver's side and cause this. I don't think its the chip or injectors. Please let us know when you find out what the problem was. Good luck, Joel

It seemed to be inconsistent, and happened only in boost, i would watch the boost gauge and then the scanmaster and once the alky would kick in, right around 12 psi, the knock would dissapear within two frames on the scanmaster. Im going to be out tonight and play with it some more, to try to diganose the problem(be it a small, yet annoying one) I think transition knock and this knock are related just because they both behave the same way, once the alky kits in they dissapear after two-three frames on the scanmaster. The alky has been on the car for roughly a month, so im still kind of learning how to really "fine" tune it, but have a general idea of the concept of how it works and tuning issues with it.

PS. the pump speed is always set at 10, since im running 20-22 psi i like the car to be a little rich 780's O2s or higher to be safe.

Shoebox
 
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