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Thread: Bolt on's SD tune

  1. #1
    Potential Tuner
    Join Date
    May 2014
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    2

    Bolt on's SD tune

    So I have just received HP tuners and have started to play with it. I realize SD tuning is only common on FI or big cam applications. I plan on doing heads and cam in the very near future, but wanted to have a little more experience using HP tuners before I tried to tackle something like that. So I decided I would go ahead and convert to the 1 bar speed density enhanced OS early, so I could play with it and try running in SD mode. (maybe not my best idea) I have so far been pretty unsuccessful at tuning me VE table, I've just been adding my short term fuel trim histogram to my VE table, reflash, drive, repeat. I feel that I should just get a wideband and do it the right way. I also changed up my timing, which I regret. I get KR at 4500+ usually 2-3 however some cells I've seen as high as 6-8. Any help would be appreciated! I'm very new to this. I've attached my tune file as well. c5speeddensity1bar.hpt

  2. #2
    Advanced Tuner umrjmac's Avatar
    Join Date
    May 2010
    Location
    Lenexa, KS
    Posts
    301
    I would do a LOT of reading on the forum and consider getting some of the available print material (Banish's books, material from the Tuning School, etc.).

    I would order a wideband. If you got the pro version of HPTuners you can wire the 0-5V output straight to the box through the green connector, otherwise you have to use one of a couple of sensor inputs from the car (search and you'll find info...I think one is an EGR sensor, I forget the other). The narrowband sensors aren't accurate when your commanded AFR/Lambda isn't stoich, so if you have any power enrichment the values that the narrowband sensors show are useless. Also, when you go into PE, the LTFT/STFT sort of locks for the pull until you leave PE, so you could have a ton of logged data that shows a "wrong" LTFT/STFT value for that particular cell. While I appreciate the datapoint for knock at 4500 RPM, without a wideband you don't know if your actual AFR/Lambda is wrong (i.e. you need to adjust your VE table), if you are commanding too much timing, or if it is something different entirely.

    I would revert your timing changes until you figure out the right order to make changes and what each change does and why you make them. You mention that you regret making that change. Put it back. Nothing says that you have to build iteratively off of the same tune file after making changes that adversely effected things. Knock is bad. The values that you've listed are within the PCM's ability to pull timing, but its better to be safe than sorry.

    It may suck to table some of the hands on work while you educate yourself, but it sucks more to replace a motor if you accidentally make a bad change.
    Kenne Bell Supercharged 2003 Corvette Z06

  3. #3
    Potential Tuner
    Join Date
    May 2014
    Posts
    2
    Thanks that helps a lot! The first thing I am going to do is order a wideband. I'm really finding out it's not optional. I do have the regular MPVI, so I will be hooking it up to the EGR input. Unless I did something wrong I believe I disabled the PE so it wouldn't skew my STFT/LTFT. I will just be putting it back to stock timing until I get my wideband, although I've been reading that stock timing tables are pretty dead on from the factory and there isn't much to be gained with just bolt on's. Anything else I should look to change from the stock tune with my mods?