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Thread: Cruise AF and VE tables

  1. #81
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    I think I already asked you this but did you disable burst knock?

    Burst knock will make that random 6-8 degrees of knock retard, I don't know why.

  2. #82
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    Yes you have and no I haven't. I never remember it when I've got the program up. What exactly is burst knock?

    Still wish I knew what all affected timing, and by what percentages, like the formula used for adjusting it. The only thing I can think of why it didn't work out is if the computer is using the O2 sensor for a spot check under WOT, and was seeing it "rich" since under all the previous tunes I had the O2 switchpoints kinda low. When I adjusted the VE table hoping to make it think it had less to fill none of the fields I had adjusted were being used at the time of knock. It no longer matters now though, as this weekend the truck goes back to Pop. My own truck is back on the road as of yesterday, and while I really miss the power of Pop's truck it's all I miss. I really enjoy driving my S15 ext cab, more than anything I've had since my 79 GMC halfton shortwide. Now that Interior 0.5 is complete, I'm going to take a breather, then start investigating a more powerful, efficient engine for my truck.

    Edit - Looked the burst knock tables over, and I see the reason for them. Rather than disable it, I set all values to .0016, higher than the highest value there. If airflow goes over this much, I think it would be a good idea for timing to pull back. GM wouldn't have gone through the trouble and expense to make this particular field if there wasn't a reason for it.
    Last edited by Telco; April 1st, 2008 at 11:31 AM.

  3. #83
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    I wonder if I might not have found why I was able to pull timing yet not see KR reduce. I had the B4105 O2 switch points set way down, but just noticed in table B4206 that I had Use O2 with Open Loop Commanded Fuel Table set to Enable as well. If this is the case, and I had the O2s to switch lean, then it would think that the new switch point was 14.7 and would adjust the mix according to what it thought the commanded ratio was, rather than just commanding X amount of fuel for Y amount of air. Academic now though, as I am taking the truck back to my dad today and likely won't drive it again. I've set the table to disable and will pull a log on my way down to his house to see what effect it has on a WOT run.

    Anyway, thanks for the help everyone, I really appreciate it. Hopefully I'll have a 411 controlled vehicle of my own before long, because the 2.8L in my S15 just isn't cutting it.

  4. #84
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    I'm not a happy camper now. If only I'd discovered this a week or two ago! I took the truck back to my dad's house on Saturday, driving 70-75MPH for 130 miles I burned 5.5 gallons with a few WOT runs due to traffic being stupid. This is 23.6MPG on a 2000 reg cab narrow bed Chevy with a 5.3/auto! Danged thing might see 25+MPG going 60-65 with no WOT runs. I also found the field that was forcing the truck to only downshift to 3rd gear on a WOT at 70MPH, it will now downshift to 2nd at 75MPH and is going 85+MPH in just a couple of seconds instead of 15 seconds to go up 10MPH. And, with the current tune under several WOT runs knock retard stayed less than 2 degrees. Told Pop to write down what he doesn't like and I'll try to tweak next time I visit.

    I'll post the current tune up next time I'm on the internet with his laptop, which I still have at home. May be a few days. Thanks again for the help everyone.

    Edit - Here's the latest tune. Anyone feel free to use it. I'd look at the low speed shifting, might be too low. My dad's a big fan of a transmission that shifts imperceptibly, and I've got it down a little too low.
    Attached Files Attached Files
    Last edited by Telco; April 9th, 2008 at 10:56 AM.

  5. #85
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    Yeah with my 2000 ex cab I used to avarage about 18-19 in the city and on trips going 55-65 I could get up to about 22-23 avarage.

    I don't like my trans to shift hard either except at WOT it gets anyoying

    But having efi live is annoying becuase you are constantly changing stuff and your never satisfied.

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