Knock at WOT... help?
Thread Starter
Teching In
Joined: Dec 2003
Posts: 29
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From: Kitchener, Ontario
Knock at WOT... help? Hey guys..
Finally got Autotap going on my car and confirmed some suspicions..
First.. this year I installed an ASP crank pulley on the car with the hopes of a couple more horses at the wheels on the dyno. No other changes made to the car, I installed the pulley and proceeded to pull 1 rwhp less with the ASP pulley on the car. This was somewhat bothersome to me.. but I dismissed it.. then.. as I continued to drive the car, I realized that at WOT even on the coldest days the car was popping/pining at high rpm (roughly 5500 to 5800 rpm). Kind of odd.. my car will do that on a really really hot day (sometimes) because of the lid and free flowing exhaust.. but not normal.. only started doing it consistantly after I installed the pulley.. SO.. Autotapped and saw 4 degrees knock retard at WOT up top in said RPM's..
I'm thinking this is because my ASP pulley is out of balance.. OR I installed it and didn't get it deep enough on the crank snout thus it's not flush with the engine.. (there is a small gap between the engine and the pulley base.) That would cause my KR at WOT and also be the reason why I gained nothing from the pulley at all.. and in fact lost some..
Does that make sense? Am I totally off? Also.. I remember someone saying your 02's should be around .900 mv.. is that @ WOT or regular driving/all the time.. I think mine jumped around from .675 to .890 something or whatever.. not sure.. I'm getting my autotap log from my buddy as I write this so I'll post up a link..
Please help me out if yah can!
Thanks a ton!
Finally got Autotap going on my car and confirmed some suspicions..
First.. this year I installed an ASP crank pulley on the car with the hopes of a couple more horses at the wheels on the dyno. No other changes made to the car, I installed the pulley and proceeded to pull 1 rwhp less with the ASP pulley on the car. This was somewhat bothersome to me.. but I dismissed it.. then.. as I continued to drive the car, I realized that at WOT even on the coldest days the car was popping/pining at high rpm (roughly 5500 to 5800 rpm). Kind of odd.. my car will do that on a really really hot day (sometimes) because of the lid and free flowing exhaust.. but not normal.. only started doing it consistantly after I installed the pulley.. SO.. Autotapped and saw 4 degrees knock retard at WOT up top in said RPM's..
I'm thinking this is because my ASP pulley is out of balance.. OR I installed it and didn't get it deep enough on the crank snout thus it's not flush with the engine.. (there is a small gap between the engine and the pulley base.) That would cause my KR at WOT and also be the reason why I gained nothing from the pulley at all.. and in fact lost some..
Does that make sense? Am I totally off? Also.. I remember someone saying your 02's should be around .900 mv.. is that @ WOT or regular driving/all the time.. I think mine jumped around from .675 to .890 something or whatever.. not sure.. I'm getting my autotap log from my buddy as I write this so I'll post up a link..
Please help me out if yah can!
Thanks a ton!
I hear in some rare occations that an ASP pulley can cause KR at high RPM's, What are you using to ajust PE? I would not Ajust PE any lower than 90mv w/o a wide band but than again if ur using a MAFT you should not be able to get too lean due to COT.(Cat OverTemp protection)Which dumps Extra fuel to protect the Cat's if they get too hot. Anyone please correct me if I'm wrong. 
Thread Starter
Teching In
Joined: Dec 2003
Posts: 29
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From: Kitchener, Ontario
Thanks a lot for the response!
Well I've got nothing to adjust it actually. The car is totally stock except for the bolt-ons in the sig and put down 315 rwhp/329 rwtq with what it's got (minus the pulley). Once I bolted the pulley on I was hoping for 320, but instead saw 313 no doubt because of the KR. Crappy deal...
Right now I wondering if I got the pulley deep enough on the crankshaft snout as after I'd installed everything I attempted to hit the right torque figure, then do the additional 120 degrees or whatever it is, but may not have got it all the way. I'm going to look at a friends 98 LS1 and see how deep his factory pulley goes.. my ASP has a small gap in which I can see the crankshaft between the engine and the pulley snout.. very very small, but it's there. I'm figuring if my belts were squeaking (brand new gatorbacks) it could be due to misalignment and that would also cause the KR.. I'll try getting the pulley on further if at all possible first.. then if that doesn't work, I'll put the stocker back on and assume I had a poorly balance ASP unit.. maybe they will take it back and/or balance it for me?
I've got some playing to do either way.. any other help or advice from anyone?
Well I've got nothing to adjust it actually.
The car is totally stock except for the bolt-ons in the sig and put down 315 rwhp/329 rwtq with what it's got (minus the pulley). Once I bolted the pulley on I was hoping for 320, but instead saw 313 no doubt because of the KR. Crappy deal...Right now I wondering if I got the pulley deep enough on the crankshaft snout as after I'd installed everything I attempted to hit the right torque figure, then do the additional 120 degrees or whatever it is, but may not have got it all the way. I'm going to look at a friends 98 LS1 and see how deep his factory pulley goes.. my ASP has a small gap in which I can see the crankshaft between the engine and the pulley snout.. very very small, but it's there. I'm figuring if my belts were squeaking (brand new gatorbacks) it could be due to misalignment and that would also cause the KR.. I'll try getting the pulley on further if at all possible first.. then if that doesn't work, I'll put the stocker back on and assume I had a poorly balance ASP unit.. maybe they will take it back and/or balance it for me?
I've got some playing to do either way.. any other help or advice from anyone?
If I remember correctly there is about an 1/8 of an inch of space between the pully and the seal,alot of people think the pully is not all the way on but it is. Do a search and find some pictures of the pully and seal. 
TECH Regular
Joined: Sep 2004
Posts: 404
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From: Raleigh, NC
I have the same problem with my 01. I also have ASP pully's as well but I want to say that I heard the knock before I put the pullys on. There is supposed to be a gapbetween the pully and crank seal. My knock as far as I can tell is only coming from the left bank of my engine. I was going to hook up a GM Tech 2 scanner and have a passenger check out some things during a test run.
At WOT the computer does not factor in O2 sensors, the computer goes into open loop and does not care what they are readingNormally O2 should be changing constantly from above and below .500. The constantly go back and forth from rich to lean. But at WOT yes the sensor will read close to 1V indicating a rich condition.
I have a hard time beleiving that the ASP pullys are causing the knock, but now you got me guys wondering. Please let me know if you figure something out or anyone else having a simular problem. Another LS1 owner I know said that both of his LS1 he has had knocked at high RPM under a load.
Looking closelyat my crank pully is does woble a little. Kind of scary. ASP may be getting a call.
At WOT the computer does not factor in O2 sensors, the computer goes into open loop and does not care what they are readingNormally O2 should be changing constantly from above and below .500. The constantly go back and forth from rich to lean. But at WOT yes the sensor will read close to 1V indicating a rich condition.
I have a hard time beleiving that the ASP pullys are causing the knock, but now you got me guys wondering. Please let me know if you figure something out or anyone else having a simular problem. Another LS1 owner I know said that both of his LS1 he has had knocked at high RPM under a load.
Looking closelyat my crank pully is does woble a little. Kind of scary. ASP may be getting a call.
Originally Posted by NightRiderWS6
Hey guys..
Finally got Autotap going on my car and confirmed some suspicions..
First.. this year I installed an ASP crank pulley on the car with the hopes of a couple more horses at the wheels on the dyno. No other changes made to the car, I installed the pulley and proceeded to pull 1 rwhp less with the ASP pulley on the car. This was somewhat bothersome to me.. but I dismissed it.. then.. as I continued to drive the car, I realized that at WOT even on the coldest days the car was popping/pining at high rpm (roughly 5500 to 5800 rpm). Kind of odd.. my car will do that on a really really hot day (sometimes) because of the lid and free flowing exhaust.. but not normal.. only started doing it consistantly after I installed the pulley.. SO.. Autotapped and saw 4 degrees knock retard at WOT up top in said RPM's..
I'm thinking this is because my ASP pulley is out of balance.. OR I installed it and didn't get it deep enough on the crank snout thus it's not flush with the engine.. (there is a small gap between the engine and the pulley base.) That would cause my KR at WOT and also be the reason why I gained nothing from the pulley at all.. and in fact lost some..
Does that make sense? Am I totally off? Also.. I remember someone saying your 02's should be around .900 mv.. is that @ WOT or regular driving/all the time.. I think mine jumped around from .675 to .890 something or whatever.. not sure.. I'm getting my autotap log from my buddy as I write this so I'll post up a link..
Please help me out if yah can!
Thanks a ton!
Finally got Autotap going on my car and confirmed some suspicions..
First.. this year I installed an ASP crank pulley on the car with the hopes of a couple more horses at the wheels on the dyno. No other changes made to the car, I installed the pulley and proceeded to pull 1 rwhp less with the ASP pulley on the car. This was somewhat bothersome to me.. but I dismissed it.. then.. as I continued to drive the car, I realized that at WOT even on the coldest days the car was popping/pining at high rpm (roughly 5500 to 5800 rpm). Kind of odd.. my car will do that on a really really hot day (sometimes) because of the lid and free flowing exhaust.. but not normal.. only started doing it consistantly after I installed the pulley.. SO.. Autotapped and saw 4 degrees knock retard at WOT up top in said RPM's..
I'm thinking this is because my ASP pulley is out of balance.. OR I installed it and didn't get it deep enough on the crank snout thus it's not flush with the engine.. (there is a small gap between the engine and the pulley base.) That would cause my KR at WOT and also be the reason why I gained nothing from the pulley at all.. and in fact lost some..
Does that make sense? Am I totally off? Also.. I remember someone saying your 02's should be around .900 mv.. is that @ WOT or regular driving/all the time.. I think mine jumped around from .675 to .890 something or whatever.. not sure.. I'm getting my autotap log from my buddy as I write this so I'll post up a link..
Please help me out if yah can!
Thanks a ton!
hope that helped a bit
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Teching In
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According to the Jan 2004 GM HTP mag [who trusts mags?] the gap should be
" 0.094 to 0.176 inches between the end of the crank and the seated part of the pulley." They used a pulley install tool on a TR pulley. Interestingly, they got a "slight dip in both horsepower and torque at 5800 rpm.'I would guess this is a side effect from the balancer harmonics, ' he[Chief Engineer Brian Reese]opined. " I have seen this type of thing with other balancers in the past. The dip is from balancer harmonics, not from false knock retard caused by the balancer."
I'm not sure what to make of these comments, just thought I'd pass them along.....
the 1/8 " gap advice [=0.125 "] appears to be right where you should be. I wonder if I should put my ASP pulley on now ??? Is TR's pulley an SLP pulley?
" 0.094 to 0.176 inches between the end of the crank and the seated part of the pulley." They used a pulley install tool on a TR pulley. Interestingly, they got a "slight dip in both horsepower and torque at 5800 rpm.'I would guess this is a side effect from the balancer harmonics, ' he[Chief Engineer Brian Reese]opined. " I have seen this type of thing with other balancers in the past. The dip is from balancer harmonics, not from false knock retard caused by the balancer."
I'm not sure what to make of these comments, just thought I'd pass them along.....
the 1/8 " gap advice [=0.125 "] appears to be right where you should be. I wonder if I should put my ASP pulley on now ??? Is TR's pulley an SLP pulley?
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Verdad Gallardo Thread Starter
Teching In
Joined: Dec 2003
Posts: 29
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From: Kitchener, Ontario
Thanks for the replies guys.
I pulled my pulley off, then re-installed it and thought I'd solved the problem. I couldn't hear the knock anymore up top as I had been.. (I'd hear popping before... not good.)
So.. I took the car to the track, ran it, and couldn't break 104mph for the life of me... on a cold day, with Nitto's.. (mind you I didn't heat them well enough for a decent 60' time).
Best I ran was a 13.7x @ 104.x with a 2.35 60' time. The car pulls harder down low, but up above 5300 rpm or so it just sort of nose dives.. threw a scanner on it and did a pass.. I was seeing between 2.6 and 3.1 degree's of knock at WOT upper RPM's.. not good. I'm going to be taking the pulley off and this time re-installing the stocker.. then I'll scan the car again and see where I'm at. Something definately isn't right, and the only thing that has changed on my setup at all was the ASP pulley. I've contacted a machine shop to see if they could check the pulley for balance or maybe re-balance it.. not sure if that's possible.. but I guess I'll find out! My car was running 13.4x's @ 107 mph before! Grrr...
I pulled my pulley off, then re-installed it and thought I'd solved the problem. I couldn't hear the knock anymore up top as I had been.. (I'd hear popping before... not good.)
So.. I took the car to the track, ran it, and couldn't break 104mph for the life of me... on a cold day, with Nitto's.. (mind you I didn't heat them well enough for a decent 60' time).
Best I ran was a 13.7x @ 104.x with a 2.35 60' time. The car pulls harder down low, but up above 5300 rpm or so it just sort of nose dives.. threw a scanner on it and did a pass.. I was seeing between 2.6 and 3.1 degree's of knock at WOT upper RPM's.. not good. I'm going to be taking the pulley off and this time re-installing the stocker.. then I'll scan the car again and see where I'm at. Something definately isn't right, and the only thing that has changed on my setup at all was the ASP pulley. I've contacted a machine shop to see if they could check the pulley for balance or maybe re-balance it.. not sure if that's possible.. but I guess I'll find out! My car was running 13.4x's @ 107 mph before! Grrr...
