High/Low Octane Tables Canada Vs. USA?

[n6oli]

Hello to all.
I am new to this forum and EFILive tuning.

I have a 1999 Chevy Silverado that was manufactured in Canada.
When I compare the High/Low Spark octane table from one that was manufatured in USA, the one from USA has a little more aggressive timing down in the lowend.
Why is that?

Both operting systems are OS:09373372

Both Engines: 5.3L

My built in Canada Truck:
http://img147.imageshack.us/img147/8896/image1tg5.jpg

USA Truck:
http://img160.imageshack.us/img160/5360/image2ju2.jpg


Thanks

[SSpdDmon]

Hmmm...interesting. You guys have a different type of gasoline in Canada?

[n6oli]

No I live in USA, but the truck was made in Canada and sold in the USA. I'm trying to post the pics, but having trouble with that.

[joecar]

b6oli, welecome to the forum. :cheers:

Try: http://imageshack.us/

[n6oli]

joecar, you seem to be very knowledgeable in tuning.

Does this look like Burst knock to you?

I seem to get alot of spikes like this.

http://img511.imageshack.us/img511/9248/image3ha2.jpg

[cmitchell17]

I have a 2000 truck that was made in Canada, but im in florida:eek:

anyway heres my stock tune. Im using a 2005 timing table with more timing in the fuel mixture spark correction table.

[cmitchell17]

n6oil what have you all done to your truck?

Im going to use a spreadsheet to put my optimal timing table to my high octane table.

Have you noticed any power from more timing? When do you get KR?
Can you get your transmission to give a resonably firm shift on the WOT 1-2?

I bet you can get some more low end torque with some changes in timing.
I dont no how my 5.3 got from canada to mississipi to florida. My old 95 was built in Canada too.

[cmitchell17]

I just noticed something.

Back when I started to tune i had my timing steady at 25-28 at peak torque(4000rpm) I heard that a trick was to drop timing at peak torque by 3-4 degrees.

Now since I have done this my delievered engine torque dropped from 320s to 285s. Is this just a product of decreased timing in the torque calculation. Or is decreasing your timing at peak torque a bad idea. Seems gm likes a little more timing at peak torque.

[joecar]

It's hard to tell...

Can you hear it knock...?
If you can hear it, then it is real;
If you can't hear it, then it may or may not be real;

As Tordne told me, try zeroing the burst knock retard tables and see if it goes away.

Also, if you think it's real:
- check for oil being ingested into intake thru PCV;
- check for worn or incorrect spark plugs;
- check for high IAT and/or ECT;
- check for dirty MAF and/or air filter;
- check for bad petrol/gasoline;

Try some octane booster to see what happens.

[cmitchell17]

I just tried running a tank of 87 instead of 89 93. So I definately have lower octane. I heard it during the day but at night not any more(at WOT). Its wierd sometimes even though running 89+ going up a hill in a low hear with the windows rolled up you can hear slight knock, this is with the stock timing table to.

Ive heard this on stock trucks too.

Its wierd that you acutally put a lower octane gas and you can start to hear it knock and put a higher in it and not hear it.

During the day the IAT where probably very high over 100 degrees in florida in traffic.

How could IAT make more detination, just because it is 50 degrees or so up in air temp it can make the cyl that much hotter? Just like a slightly richer mixture can cool the cly. that much?

Im going to put 93 in it next time I fill up, it is only about 3-4 dollars more a fill up, I wish I could run ethanol and get it cheap around here.

[cmitchell17]

I might try going to a colder spark plug range, and couldnt I mabey get away with running a lower octane. It seems like you should always be able to run 87 octane with a stock CR with good timing.

When does Knock get dangerous (in the manuel it says dont worry about if you hear pinging crusing up a hill) at WOT high airmass?

The way I see it is that there is a diffrence between detination and pre-ignition. That pre-ignition is when the mixture ignites before spark occurs, and detonation is when spark has occured and the mixture ignites somewhere else and it causes really high pressures in the cyl. for a very small amount of time?

[joecar]

Knock is never good, but it's deadly if sustained under load (high airmass, regardless of rpm).

[SSpdDmon]

http://en.wikipedia.org/wiki/Octane_rating

[dc_justin]

joecar, you seem to be very knowledgeable in tuning.

Does this look like Burst knock to you?

I seem to get alot of spikes like this.



Re: Burst Knock:

That isn't a symptom of Burst Knock. The effect of "Burst Knock" would be seen upon an influx of air, whereas the knock you see is at steady state and low load.
The PCM's effort to stop burst knock from ever happening is a reduction in timing that does not show up as knock retard.

[joecar]

Re: Burst Knock:

That isn't a symptom of Burst Knock. The effect of "Burst Knock" would be seen upon an influx of air, whereas the knock you see is at steady state and low load.
The PCM's effort to stop burst knock from ever happening is a reduction in timing that does not show up as knock retard.Good point. :cheers: