Thread: Knock Retard

Originally Posted by Poil336

the concept seems somewhat right. couple things though: are you just looking at the diameter when you're calculating percentage of the stock pulley? because i'm pretty sure you'd be looking at circumference with that. also, you might get 20% less O2, but you're injecting the entire contents of the atmosphere, so you should think about air density as compared to sea level and not oxygen density.

another thing to think about is that the pcm is used to the density of the air, and was getting the correct air fuel mix before you put the pulley on. if what you think is happening is the case, then the pcm probably just has enough timing to pull to have you not knock.

i'd really really like to see a scan on this motor.

pi*d is the circumference of the pulley. Since pi and crank RPM remain constant, the only variable is d.

I've pulled the plugs many times and they pristine.

The reason I asked "should I care" is because if the ECM via the KS is capable of properly retarding the timing to prevent knock, then what is the issue?

I will write this once again...

It's never once thrown a code. It's never once not run propely. I've had the pulley on for 1+ year and have almost 20k miles on it.

Do any of you have any information for running a smaller pulley at 5500 ft altitude and 20% less dense air? My guess, I could take my car to sea level and immediately see problems. But, I'm not at sea level.

My uncle has a scanner. I'll pull the info and see what's happening. But, nobody answered my question: do you scan as it runs in real time to monitor KR or does the scanner store its values?

I don't have the pulley on for performance per se. I changed my coupling year ago decided "while I'm at it...". This is my daily driver - I have another car for my performance fix.

In short, I have no interest in seriously undermining its reliability. But, I've also seen no problems whatsoever (other than people telling me "no!!!").

So, what's left to be determined is whether or not you guys are underestimating or ignoring the effect of air density or whether I've just been lucky over the last year or so.

Hi, I'm at 6000ft here, been running stock pulley and I run 92 octane fuel on a 98 GTP.

1. when I first bought the car, I used regular fuel and the car ran like crap for a week until I found out that it should be premium fuel.

2. I could tell if I had KR without a scanner when I was almost stock: When I did WOT from 0, after I got to 2nd gear, I let go off the gas pedal just a little bit, the car would actually accelerate more at around 90% than it did at WOT.

The more mods I did, the less I could feel this, first with a Ubend delete, 3" DP and now with headers it's completely gone.

3. I'm installing a 3.4 pulley next week or so then I'll actually find a way to scan the car for Knock although I should probably do it first.

Originally Posted by SJAndrew

if the ECM via the KS is capable of properly retarding the timing to prevent knock, then what is the issue?

You've got it backwards. KR prevents more knocking. the PCM doesn't have ESP to know to prevent knocking from starting. You have to knock FIRST before the timing gets pulled. How the hell else would it know? For all your education, you're making yourself out to be a box of rocks. Here's a simple, chronological list of events that are happening to your car:

1. Open throttle
2. Knock
3. Knock retard; Engine power decreased; Possible continued knock

You see, every time your foot touches the petal, you knock at least once before the timing gets pulled. So, you're knocking... a few hundred times a day at least, granted that knock retard pulls enough timing to prevent more knock?

But hell, you're right: Your unfounded assumption just might be right (unknown unknowns don't remotely make an "equation" valid [read: No.]). Unfortunately, nothing you say will make a difference to anyone else until you have proof. So, do what everyone else says: Scan it, or GTFO. Seriously, you came to us; we didn't come to you.

Their is a ton of OWN in this thread that is all/
subscribed

I've had this car since it was brand new - 13 years. I ran 92 octane for the first ~9 years of its life until I ran some 85 octane when gas skyrocketed in price. Other than the $0.80/gallon saving, there was no difference whatsoever. Mileage, performance et al all remained identical.

The car has 124k miles on it - 20k on the new pulley.

My assumptions aren't unfounded. Air is less dense here - about 20%. That isn't something I pulled out of my ass - it's a fact. Other than an simple assertion that I'm wrong - please, someone, give me insight as to why I'm wrong.

The bottom line here: none of us knows for sure what's going on.

I will scan it and find out. I'd love to know either way.

Perhaps it's a combination of altitude, a worn out timing chain, and luck.

What I'm disappointed in is that answers to my question are in the form of mockery and insults. I came here for information - I presented my case, and will endeavor to prove it (if nothing to myself). Your responses, for the most part, has been disappointingly negative and uninformative

I'm sorry for wasting your (and my) time.

A bit more straightforward:

Originally Posted by SJAndrew

My question: could I still be having "too much KR" as a result of the pulley swap but not know it because my ECM is doing the work for me?
...
Or - let me put it another way: do you need a scanner to know if you're getting too much KR?

Yes, you absolutely must scan to know if, and how much knock retard you have and where in your powerband.

Originally Posted by SJAndrew

I always figured that a smaller pulley put me closer to stock at sea level.

I figure that the rotational speed of the pulley is close to linear to its output (this is not really the case as air is compressible, but it's close).
...
If the rotational speed is somewhat linearly representative to the CFM, then I'm getting back to sea level (or so).
...
One question along those lines: do you monitor KR real-time (my assumption) or is it stored in the ECM?

There's a lot of assumption here that will be fixed with a scan; when it comes to blowing up an engine, that simply won't cut it.

Originally Posted by SJAndrew

nobody answered my question: do you scan as it runs in real time to monitor KR or does the scanner store its values?

KR is monitored close to real-time. There's a delay, as I understand it.

Originally Posted by SJAndrew

I ran some 85 octane ...there was no difference whatsoever. Mileage, performance et al all remained identical.

My understanding of fuel in extreme atmospheres is lacking... perhaps someone like Reptile could point you in the right direction here.

Originally Posted by SJAndrew

What I'm disappointed in is that answers to my question are in the form of mockery and insults. I came here for information - I presented my case, and will endeavor to prove it (if nothing to myself). Your responses, for the most part, has been disappointingly negative and uninformative

I'm sorry for wasting your (and my) time.

1. Everyone's a dick on the Internet, especially forums. It can't be helped - it's a land of chaos where children and adults mingle. If you're here, you deal with it.
2. You've shown little in the way of your own research regarding the topic, but persist in your point. This is irritating to some of the community, because many of them have provided a lot of information to help others (which you seem to have ignored/disregarded) - many, to the detriment of their vehicles and wallets. There is a collection of generally-accepted rules-of-thumb because the combination works every time. You challenged this unprepared, and received the response you deserve for it.

Originally Posted by SJAndrew

The reason I asked "should I care" is because if the ECM via the KS is capable of properly retarding the timing to prevent knock, then what is the issue?

Because it cant.

Our cars dont have sensors that retard timing based on the octane of the fuel we're running through it.

If they did, then putting race gas in it would actually make it much faster without any other adjustments.

Since they dont have these sensors, they can only react.

And a reaction to detonation is not what you want.

You want there to be no detonation to begin with.

If you dont understand that, then I dont see any hope in you "finding" the answer on your own.

As for the negativity.... You're running your car with a 3.2 pulley on 85 octane fuel.

That is typically a recipe for disaster but you seem to say "its been fine so it'll still be fine".

Your claim holds no weight here unless you actively scan for KR.