help me brainstorm on knock retard please

msheller

msheller

New member
I'm trying to decrease a slight to moderate knock retard issue. So, I was hoping we could brainstorm up all the possible sources of true and fake knock signal in an effort to come up with a comprehensive list for the board...

I'll get us started: low octane fuel, excessively aggressive timing, exhaust banging?, too much boost at too low of an rpm under too heavy of a load on motor, and... help me out here guys...

matt
 
mrweelr

mrweelr

New member
Re: help me brainstorm on knock retard please

-Incorrect base ignition timing
-Poor boost control (stock turbo/wastegate)
-High IA and/or coolant temps
-Wrong plugs (heat range too high)
-Knock sensor too tight
-Bad ECM or low ECM voltage?
-Fuel pressure inadequate
-Carbon buildup in intake, heads, cylinders
-Broken motor mounts?

Those are just some ideas, take it FWIW. I spent a lot of time replacing parts on my Sy to reduce KR, with little luck. After doing all the major upgrades this past year, the KR basically went away. This is with the same bone stock 71K motor and crappy 91 octane. Now, KR only spikes to 1 degrees, occasionally, on 91 octane w/no alky spray. You can really feel it when the ECM is pulling out timing. I'm pretty sure the fix for me was the external wastegate and Blitz EBC (no more boost spikes). The solid motor mounts, Phil Long chip, and 50# injectors probably didn't hurt either.
 
Jimmy

Jimmy

Banned
Re: help me brainstorm on knock retard please

When is it happening? Have you looked at your plugs?
 
msheller

msheller

New member
Re: help me brainstorm on knock retard please

w/ alcohol on...it happens most on downshifts/boost spike, part throttle accel, and non-brake stand launches....increasing the octane to almost full 118 sunoco supreme has reduced knock retard to max of 6 degrees on full pull, which in contrast to 16-17 max kr from last week on 94 is pretty good

how hard are motor mounts to do?

btw, are iac readings of 80-90 ok? It sometimes stalls... nothing else seems weird on diacom datalogging..no trouble codes

Matt
 
mrweelr

mrweelr

New member
Re: help me brainstorm on knock retard please

That's a whole lot of KR there for 94 octane. Something's not right. Have you checked your base timing with a piston stop and then double-checked again? Do you have a WBO2? What's your AFR range at WOT?
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: help me brainstorm on knock retard please

Do a search on my forum name and knock retard. I have never figured out my problem though, but I may have hurt my motor in testing trying to find the problem :(. It seems like me you KR is real, since race gas helped 10 degree of timing.
 
msheller

msheller

New member
Re: help me brainstorm on knock retard please

mrweelr said:
That's a whole lot of KR there for 94 octane. Something's not right. Have you checked your base timing with a piston stop and then double-checked again? Do you have a WBO2? What's your AFR range at WOT?
Click to expand...

thanx 4 the help----the o2 is over 900mv at wot, we have checked base timing, but have not double checked it.

BTW I have had very rich running conditions periodically since the pte 52 kit etc. several months ago...and I've used alot of leaded fuel with the o2...do u think the o2 is ruined/could contribute to knock? could fouled plugs contribute to knock?

Matt
 
msheller

msheller

New member
Re: help me brainstorm on knock retard please

dgoodhue said:
Do a search on my forum name and knock retard. I have never figured out my problem though, but I may have hurt my motor in testing trying to find the problem :(. It seems like me you KR is real, since race gas helped 10 degree of timing.
Click to expand...

OK, what is "my forum name"?
thanx
Matt
 
mrweelr

mrweelr

New member
Re: help me brainstorm on knock retard please

You might try swapping the injectors and replacing the O2 sensor probably wouldn't be a bad idea either.
 
9

93ty475

Donating Member
Re: help me brainstorm on knock retard please

msheller said:
btw, are iac readings of 80-90 ok? It sometimes stalls... nothing else seems weird on diacom datalogging..no trouble codes

Matt
Click to expand...



at idle? sounds kinda high to me...
 
msheller

msheller

New member
Re: help me brainstorm on knock retard please

BTW, this help is great...once again thanx.

The rockers are stock.

I plan to do the ur6 plugs tomorrow(cr42ts delco in now) at .028, and buy new iac and o2 to try later... and the diacom runs continue... I don't think knock retard of max 6-7 per full pull will hurt it do u? The sunoco supreme is getting real expensive...turning my 3 times per week driver into my toy driven one time per week... but, I am exercising my new tranny very well while still under warranty though

Matt
 
msheller

msheller

New member
Re: help me brainstorm on knock retard please

mrweelr said:
You might try swapping the injectors and replacing the O2 sensor probably wouldn't be a bad idea either.
Click to expand...

I have only one set of 50# inj's...did you mean swap plugs?...THAT I can do

MATT
 
msheller

msheller

New member
Re: help me brainstorm on knock retard please

msheller said:
thanx...the more u know the better

matt
Click to expand...


Wow,

dgoodhue--thanx 4 those links to the old kn retaRD threads... Really good info!

UR6 plugs going in finally tomorrow---I'll try to post knock retard results

Matt
 
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