How do I get rid of this knock

[redhotrod]

Hey guys,
I want to take the TR to the track tomorrow, but I am getting some nasty knock hi in the rpms, around 3800 rpms, up to 14 kr.
On the turbolink, i notice my O2's are dropping up there and the gps on the maf are slowly rising. at cruise my blms are at 105, at wot, 128, I have an adjustable 237 reg. set at 42lbs vacuum line off. Walbro 340 is in the tank, but not hotwired. Still have stock injectors, tb, turbo but the heads and intake are homeported and polished. No codes are coming up, other than my vss 24, but I should have that code fixed now. Any one got any clues for my knock, If I get into the throttle easy, knock hits 4.5kr. If i step on it, it shoots up to 14
Help!!

 

[crazygn]

Any vac or exhaust leaks, What kind of boost are you running with the 42psi fuel press, and what are your o2's at wot. Have you check any of your plug wires to make sure one is not burnt.

hope i can help

 

[redhotrod]

Thanks
no vacuum leaks, all new, as of 2 weeks ago. No exhaust leaks. Motor was just put together 150 miles ago
I only got the boost set to 12 psi, if I get on it hard, knock is right there, o2s are at 820 then slip down to 800 when knock starts

 

[crazygn]

did you tourqe your knock sensor at the right lb when put back together. Maybe false knock.

 

[redhotrod]

I actually left the knock sensor alone when I worked on the block. you can sometimes hear the detonation when it gets up there around 13kr, I use sunoco ultra 94 and with only 12 psi boost, I would think there shouldn't be any knock.
It looks like for some reason its going lean on hi Rs, cuz o2s are slowly dropping while maf is slowly climbing. The blms at 105 are telling me its running rich though right?
I have a new o2 sensor, new ac delco cr43ts gapped at .031, new 8mm wires, I also have a bigger 212 comp cam, so I would imagine its sucking more air than stock, along with the ported stock heads. Any more Ideas?

 

[gary brooke]

knock

i hope this will help,when i got my car running.93 oct.1# boost,knock like hell.i put 100 oct. in with no other changes,and at 14# boost i get 0 knock.

 

[Nocooler]

What chip are you running??

 

[6SENSE]

Do you have a FP gauge that you can watch while you are driving? You need to watch the fuel pressure while you are under boost and see if it tops out at a certain amount while the boost is still climbing (your going to have to get on it; the highway is good for this because you can get on it gradually to build higher boost and watch the #s, and get out of it if you have to). Remember, youve got to match 1psi of boost with 1psi of fuel pressure. If this isnt happening youve found your problem. Probably crap in the fuel lines. Change your fuel filter, its probably clogged.

Next thing to try: turn your boost down to something low, like 8psi? You want to identify the problem as actual detonation and not false knock. If it doesnt want to go away with really low boost, then youve got false knock from somewhere. Exhaust pipes (i.e. downpipe, hitting A-arm, etc.) are sometimes culprits. The heatshield on the heater/AC box. Also, any sounds from the engine. A noisy valve train will do it for sure (lifters, rockers, pushrods, timing chain). Do you have any tapping from the motor? Did you check for proper lifter prelod when installing the aftermarket cam? If not enough preload the pushrods/lifters will chatter, especially at higer RPMs.

 

[xxninja]

i have heard that anything over 800 on the o2's is kinda pig rich
why not turn your Fuel pressure down about 2-5 pounds, see of it makes a difference. I hear, the perfect o2 readings are .750-.775


42# lbs of fuel pressure is rather high for a hot aired regal
most of the after market chips call for #42 of fuel pressure
but thats cuz those chips are made for cars with an intercooler.
alot of the guys that use the chips for the intercooled cars, like the thrasher or Jc chips etc
put there Fp at around #38 psi, line off
hot airs dont need hardly as much fuel as the intercooleds
when you turn it down your blm's should go back up
128 would be an awesome blm number to acheive (good luck tho)

i think most guys would tell ya that , with a stock turbo, you wouldnt need that much FP
Lean it out, maybe you will get some more power out of that car

i would think , its not about how many pounds of fuel pressure you have, but more about the right mixture of fuel n air.

 

[redhotrod]

Well, went to the track.
I turned the fp down to 38 line off. o2's where in the high 700's, but man, the knock was out of hand! Boost was at 15, raced a ford fukus and had to get in and out of it all the way down the track cuz of knock. Still beat em, at a lousy 15.8 sec, 86 mph. So i turned the boost way down, to 10 psi. Stood on the gas all the way down the track, thought the pedal was gonna go through the floor, absolutely no knock, also absolutely no power. Ran a 15.973 @ 86.467 mph, and lost due to the fact I dialed in a 14.00, figured I should have been able to get that if I could have stayed in it with enough boost.
On the way home, I turned the boost up 2 turns, playing around on the way home, the knock wasn't nearly as bad, just 1 light on the knock gauge and pulled really hard, also turned the fp down to 36 static cuz the blms were still at 106.
I guess I need more octane and need to install some alcohol