I hate knock!!

[Joeld]

Had dual exhaust installed as original muffler gave up the ghost

installed cleaned and flow tested stock injectors last week

Hard pull no knock

Took her out tonight and 1-3.3 knock at 790-815.

15lbs boost, 93 pump gas, 43-44 psi line off

Why clean a week ago and knock today?

Gas is a couple of weeks old

Saw knock prior to downshift from third to second as at first I thought maybe false knock but buddy saw knock prior to downshift.

Thanks
Joel

 

[chris romani]

something is hitting o2s are great

 

[Joeld]

Thanks Chris
Is it possible to have real knock and good o2's?
I apologize ahead of time for my ignorance
Joel

 

[Gene Van Horn]

Could be something as simple as the tempeture outside, never know. Maybe think about a alky kit just be safe.

 

[Joeld]

Yes thought of alky
I'm trying to get as clean tune as I can as stock as possible
I would think that at 15lbs I should be able to get clean without too much trouble?
Man these cars are not easy

 

[Gene Van Horn]

No, they are not, but at 15 pounds and those O2s you shouldnt see any knock. Could be false, especially if it was downshifting, give it another try just have someone watching so you can let off.

 

[Joeld]

wI'll do
Any advice on trying to tell false from true knock?
Any thoughts on possible causes of real knock?
I'll check fuel pressure again
Thanks
Joel

 

[626gn]

Make a pull in third gear easing into it so it doesn't downshift. Let the boost climb slowly while watching carefully for knock. Real knock will usually escalate. Bringing your octane up a little before testing would be good insurance.

 

[Gene Van Horn]

Any real knock can lead to head gasket failure. Check your new exhaust, could be hitting somewhere when getting on it or when braking or when hit a bump. Does the knock sensor work? Tap arount with a wrench or hammer see if it lights up. How is it running does it feel different at wot. No knock before new exhuast, now knock. Give it the shake test on exhuast. How are the rest of scanmaster reading, iac, tps?..

 

[Joeld]

When you say lights up, does the sensor itself have an indicator light? I am seeing the knock via scan master.
I can provide other numbers at idle, those are the numbers you are asking about correct? Not sure if I can recall them from WOT? Right?
Yes, I try to be very careful with knock and always lift if I see, but I know too late technically at that point
Tough to sort, dammed if you do and dammed if you don't
Argh

 

[626gn]

Identifying if knock is false is usually easier than figuring out where its coming from

 

[Joeld]

Frustrating when you think you have it sorted and it comes back.

Unfortunately penicillin doesn't help.

Joel