Knock retard

[03AV]

I have a 2003 Avalanche 5.3 with a U7195,my question is.
Is it normal to be getting knock retard under light throttle? I am getting upwards of up to 3-4 degrees at times but usually it will hover around 1-2 degrees. I am also getting some under WOT. I am currently running the 87 tune. Do I need to try and pull some timing out of it or is this within acceptable range? Also is there an adjustment for part throttle timing? I know its a lot of questions but based on what I have read in these forums someone has some insight.

Thanks

[06MonteSS]

nah, you shouldn't be getting KR like that...

what are you using for gas??

you want to use good quality fuel such as Mobil, Exxon, Sunoco, Amoco or BP...

I used to get a bunch of KR when I used Shell gas, which I thought was "good"... but after talking to the diablo guys here, I changed to Mobil and it got rid of it...


no, there are no user-adjustable parameters for part-throttle timing/spark advance - only for WOT...

[03AV]

OK, I will change brands and see if any of that clears up. With that being said should I wait to make any adjustments untill after I have tried changing fuels? What about LTFT's should I leave those alone too or are those ok to change?

[06MonteSS]

yeah, don't make any timing/spark advance changes yet.. get a tank full of good gas through there first

you can adjust the injector slope now to get your ltft's in range though...

[03AV]

I am leaving for a 18hr trip to Colorado Saturday morning. Since I don't have logging abilities I will have my wife watch the readings and take an average. It will give her something to do.
On a side note, are the changes in elevation going to skew the readings any? I am going from Dallas,TX (elevation ?) to elevation of about 12,000ft. Should I just wait untill I return to try and tune for the elevation I live in?

I am sure I am just making this more difficult than it needs to be.

[06MonteSS]

yes, elevation will make a difference - due to the different density of the air, it will affect your air/fuel ratio...

be sure to check the numbers while driving in the area where you live...

and to get good numbers, you want to be driving at about 20-25% throttle position, at 2000-2500 rpms, at around 60 mph... if you have an A4, drive in 3 to achieve this.

[03AV]

Thanks so much for all the information and help.

This is exactly why I bought the predator.

[CANUCKPREDATOR]

Not to highjack the thread, but I have 4.10 gearing and 2000-2500 in third puts me about 45 mph. I'm a rolling road block. Really can't find a quiet stretch of road to do that combination properly. Does it have to 3 third gear? 4 gear at 2000-2500 is acceptable highway speed so I'm not a hazard.

[mikel]

Thats fine, as long as you are in the right rpm range.

Thanks

[CANUCKPREDATOR]

So RPM is more important than gear? Because I have a perfect place to log. There is a hill that I drive up almost daily that is about 3 miles long, not steep enough to make the truck downshift, but it does put some load on it. There is also a nice flat stretch before that you can do a good WOT pull.

[06MonteSS]

yeah, that should work... just keep your rpm's at about 2200 to 2500 rpms...

[oldgoatgoesnew]

I also had troubles with KR and generic gas. I am running a 91 octane tune and like an idiot, cheap SOB, I put COSTCO gas in my GTO--WHAT A MISTAKE!! On my sub-par gas, I was getting 3-5 degrees of KR at WOT. I would also prescribe one tank of good gas and no tune mods, and see if this clears-up your engine acne.