Mystery Knock Retard - 2001 + -- **Updated with logs**

[strobhen]

Everything I can tell you about my car that I think matters:

2001 y87
Stock thermo (not changing for the time being)
Water Wetter in coolant
Maft+ hooked up correctly
Using obd-2 scanning software
Just changed plugs yesterday, tr55's at .065 gap, feel a sotp difference (a good one)
Old plugs were well coated in carbon
CAI, holley filter, Free ram air
full 3" exhaust & cat, O2 simm
stock ignition system besides spark plugs

W/ maft+ at base (ie, no change from stock) settings
I go wot, 99% of the time, my kr is 0, for split seconds I will see kr of .8 or .3 (and I do mean split second)
I go wot w/ 2 deg advance, I see kr from 1-4, I can usually feel the loss
My knock count stays at 0, it always has

My theories:
1. the obd-2 scanning software is not correctly giving me knock counts
-AND-
A. I am getting knock from the carbon buildup
B. I am getting knock from a problem detailed on the glubgp message boards (misaligned gasket glows red hot & causes detonation)
C. I am getting knock from the slightly wider than stock gapping
D. I am getting knock because I'm unlucky and my car is running hot or something like that.

-Or-
2. Obd-2 scanning software is right, and my computer is limiting timing regardless if it hears knock or not.
3. Obd-2 scanning software is right and I have bad knock sensors, the computer knows this, and is limiting timing because of it. (but I'm sure this would cause an ses light, which I do not have)

Anyone have experience to support or dispell any of these theories?

[ January 22, 2003: Message edited by: strobhen ]</p>

[Magnus]

you get no knock with it set at zero however when you add timing you get knock..

it seems rather simple that that is too much timing. You need to look at why it is too much timing.

which means your octain may be low, you might have too much back pressure, or you may not be running rich enough.

[Ttop34]

I don't have anything helpful to say here but I was reading and noticed something. 75th Anniversary addition? Did they make the Camaro in 1926? I've having a few KR problems too, we should all just take these things out and run over them with our cars.

Wups, retarded, you have a firebird anyways.

[ January 21, 2003: Message edited by: Ttop34 ]</p>

[strobhen]

Magnus: Did you read the entire post?

I'm running 94 octane
I have a 3" exhaust
My spark plugs have carbon buildup

(plenty of octane, should be fine on exhaust, carbon buildup ='s running too rich, or weak ignition, which sounds kinda weird considering how you have said several times the 3.8 igntion is a very good one)

I am getting knock retard without seeing the knock counter go up. It stays at 0 regardless of the amount of KR I show. I consider that a tad wierd.

I look at plenty of people that can run at least 2 degrees of advance, I cannot. Its about 40 degrees outside and I'm looking for helpful advice as to why I am getting the kr.

I respect your know how, but the reply was insulting and quite useless to the subject at hand. I'm here to learn, I shouldn't even have to type a response like this.

Oh, and its 75th anniversary for Pontiac the company, not the car. [img]smile.gif[/img]

So anyone have any constructive ideas or suggestions.

[ January 21, 2003: Message edited by: strobhen ]</p>

[Blazzin Joe]

<blockquote>quote:</font><hr>Originally posted by strobhen:
Magnus: Did you read the entire post?

I'm running 94 octane
I have a 3" exhaust
My spark plugs have carbon buildup

(plenty of octane, should be fine on exhaust, carbon buildup ='s running too rich, or weak ignition, which sounds kinda weird considering how you have said several times the 3.8 igntion is a very good one)

I am getting knock retard without seeing the knock counter go up. It stays at 0 regardless of the amount of KR I show. I consider that a tad wierd.

I look at plenty of people that can run at least 2 degrees of advance, I cannot. Its about 40 degrees outside and I'm looking for helpful advice as to why I am getting the kr.

I respect your know how, but the reply was insulting and quite useless to the subject at hand. I'm here to learn, I shouldn't even have to type a response like this.

Oh, and its 75th anniversary for Pontiac the company, not the car. [img]smile.gif[/img]

So anyone have any constructive ideas or suggestions.

[ January 21, 2003: Message edited by: strobhen ]<hr></blockquote>


Im going to ignore part of your post and give you a specific mission. You say your plugs appear to be run rich or have weak ignition. I want you to log your 02' sensor readings. Come back to us with that information and we would be able to more accurately discount some of your theories. If you are running rich or lean its going to show in your 02 readings. Im suprised you werent logging these to begin with.

[ January 21, 2003: Message edited by: Blazzin Joe ]</p>

[Ttop34]

What exactly is the knock count? I'm getting the same thing. I get 14.9 degrees of knock retard yet my knock count stays at 0, does that make sense?

[Magnus]

strobhen, I did not read the entire post. I've been very busy lately. I appologize.

How many miles were on the carbon buildup plugs?

Don't worry about the knock counter. Just look at degrees for now. I'm not sure how they are related but I don't think you NEED counter activity for KR.

Damn i must have pissed you off. :(

how much timing are you getitng as is?

Your post is misleading cause you say you changed plugs and then give knock results.. I thought perhaps those were with the new plugs, once again I appologize.

I highly doubt you have a bad knock sensor.

I need to see some new autotap logs.

[Magnus]

Also, what happens when you add 2 degrees of advance and richen it up by say 10%... do you STILL get knock?

[strobhen]

Its ok Magnus [img]smile.gif[/img]

Questions, questions:
Nope, I am not seeing a difference in KR due to the plugs. No worse, no better.

Carbon buildup is after 27k miles. Car usually runs regular though I have been using premium lately.

I have been taking O2 readings and they are nothing out of the ordinary for stock cars, at wot they hang around .900-.920. I honestly have not done a lot of playing around with the settings.

As for posting logs, I may need to wait until tomorrow night for that. FOr some reason obd-2 isn't saving the logs, I have been reading them right off the screen while making WOT runs on deserted roads.

I'll work with it some and get something by tomorrow night, if nothing else, I will post some older logs.

Edit: Just saw your other post -- I have tried richening it a tad before the plug change and that seemed to help ever so slightly. I will try tonight & report the results (and hopefully post a log).

[ January 21, 2003: Message edited by: strobhen ]</p>

[Magnus]

be sure to watch what your timing is at. IF you're already over 25 degrees or so you may just be reaching your engines peak.. if your around 20-22 like a typical V6 then I'd worry.

[strobhen]

Question -- don't need to go into huge detail, but what would be limiting me from going above 25 degrees under the assumption that is the engine's peak.

Also, how much timing were you seeing at the track when your internals were still stock.

I realize, different engines, different possibilities, but I'm curious nonetheless

I am kinda thinking that just like the 160 deg thermo doesn't work on 2000+ cars, maybe they put something in there to electronically limit timing?

(This is becoming more & more like a chat session, hehe)

[ January 21, 2003: Message edited by: strobhen ]</p>

[Magnus]

Well I don't mind helping. Even more so I don't like upsetting people.

Reasons why 25 degrees could be max:
Low Octain/Bad Fuel
High Compression (unlikely)
Hot cyl temps (perhaps but unlikely)
Crappy plugs
Too Lean

With stock internals I was able to push 29 degrees in cold weather. Any more I would get KR.

[strobhen]

K, I will see where I am tonight, thanks for the help, will update soon as I have some new nfo.

[black98V6]

I am wondering something about this mystery knock retard issue. Knock occurs from premature detonation caused by something being too hot.. I wonder if GM just screwed up and we really NEED colder plugs.
That is if my understanding of what makes a colder plug, (the spark isn't as hot??)

If the spark isn't as hot it seems like you would stand less chance of premature detonation, or uneven detonation in the combustion chamber..

So am I WAY off base or what?

[67-03 RIP]

If the plugs were fouled pretty bad, maybe you've got a fair amount of carbon buildup on the piston tops. This could raise compression *slightly* making it easier to detonate. If the pistons are pretty carbon coated, it can cause hot spots (the carbon getting red hot) and detonation.

In the carb days, you'd just trickle some water down the carb and it'd steam clean the piston tops and exhaust ports (actually worked rather well)

Ron