knock Question

[pwhite]

My car has had a knock problem since a motor build about a year ago. under boost (any boost even 10#) i get a bunch of knock on the scan master ( like 19.9 ) goes away in third gear I have tried it all and still get knock. c-16 and 10 pounds of boost and still get 19.9


I recently bought a wide band from inovate and the car never gos any leaner than 10.4 to 1 .. I wired the knock sensor to a switch and with the knock sensor off and 100 octane 15 #s of boost the car runs good 10.4 to1 never any leaner,


my question is could this be anything but false knock. if so what ?
Is there any thing in the motor that could cause this (clearance problems ect.) how safe is it to tune with a wide band and no knock sensor as long as I have octaine and stay around 11 to1



Sorry for the long post

 

[steve davis]

knock

check your clearences ,downpipe,hitting the frame.header hitting the frame,it sounds like its got to be false knock

 

[pwhite]

I have checked all the outside the motor clearance problems. dp trans mount flex plate ( for cracks) . I was more so meaning internal motor problems that could cause knock ?


what do is the general thoughts on tuning with the wide band and no knock sensor?

 

[pwhite]

ttt

 

[BoostKillsStres]

10.4:1 A/F is pretty rich but thats a general statement depending on each cars setup and what it likes at WOT. I have mine running in the 11.5:1 range and tune for zero knock. I would think w/ that much knock being reported you would be able to hear something when under the hood and just blipping the throttle, have you tried that? When my stock timing chain started to go I would see 10+ degrees just going 1/4 throttle and no boost, it was simply the cam going adv/retard very fast and making noise the sensor would pick up but I could also hear it when under the hood and blipping the throttle.

You said you checked for a cracked flex plate but did you put a wrench on the bolts and check them?

By the way, rich knock is also possible.

HTH

 

[Jerryl]

How many miles on the motor?
What do you plugs look like?

 

[pwhite]

I checked for cracks when my tranny went out (yes I checked the bolts)

When in park i can rev it pretty hard and get the same 19.9 degrees of knock.
it seems to only happen at motor speeds 4000 rpms or better.

the motor has about 1000 miles and was built by a good machine shop....... not a turbo buick shop but i gave him all the clearances numbers .

plugs look normal

I have the car tuned to 11.4 to1 running 100LL and 18 degree street chip. at 22 pounds of boost

No audible knock can be heard

 

[BoostKillsStres]

knock sensor installed at the correct 14 ft/lbs?

 

[pwhite]

changed it twice just to be sure

14 ibs with 2 wraps of tef. tape

 

[BoostKillsStres]

dang, sorry to hear that, there is hope, here's the big knock checklist:
http://www.geocities.com/rad87gn/tech/knocklist.html
good luck in the hunt.
HTH

 

[pwhite]

I had the car at a very well known turbo buick shop in houston and they said it had to be internal motor noise or my trans going south . my trans was starting to slip so I replaced it and the problem is still there.

I s it possable to tune with out the knock sensor and with a wide band . as long as I have octane and a 11 to 1 af should that indicate a safe tune

thanks for all the helpful posts

 

[BoostKillsStres]

sure its possible, just lookup everything you can on plug reading and become your own expert. Make sure you never see any dark specs on the plug porcelain showing signs of detonation. An egt meter w/ a max hold feature would be nice too.