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Thread: 1999 LQ4 - Suggestions

  1. #11
    Lifetime Member Cougar281's Avatar
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    Just out of curiosity, why are those castings in the "Stay away" category? I don't think we'll do any kind of headswap on it; Any tuning we may or may not do on it will likely be relatively short term, as our "tentative" plan is to swap a Duramax into it at some point. Not sure which cone yet, but I'm hoping to find a good LBZ doaner truck to convert the whole truck over to newer stuff.

  2. #12
    Senior Member Sid447's Avatar
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    "Stay away,"

    ......Is aimed at the people who want to get the best out of them.

    Easy thing for you to do as a suggestion, is flash in a later LQ4/LQ9 stock tune file from holdencrazy.com (stock tunes) I would think.

  3. #13
    Lifetime Member Cougar281's Avatar
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    Quote Originally Posted by Sid447 View Post
    "Stay away,"

    ......Is aimed at the people who want to get the best out of them.

    Easy thing for you to do as a suggestion, is flash in a later LQ4/LQ9 stock tune file from holdencrazy.com (stock tunes) I would think.
    That had gone through my mind, as well as copying tables from a Sierra Denali's tune to get the 325/370 that it puts out. Wouldn't an LQ9 tune not work too well as it has flat top pistons, thus higher compression?

  4. #14
    Senior Member Sid447's Avatar
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    Quote Originally Posted by Cougar281 View Post
    That had gone through my mind, as well as copying tables from a Sierra Denali's tune to get the 325/370 that it puts out. Wouldn't an LQ9 tune not work too well as it has flat top pistons, thus higher compression?
    As long as you use a pre '04 tune for the IFR reference table and the rest from a LQ9 file, I don't see why it won't work. It even has the same Maf Sensor Calibration as yours. The later VE tables look a lot better than the early ones too.

    The ignition timing table actually moderated somewhat from around 2002 and stayed un-changed for quite a few years. So it must be pretty bullet- proof.

    Have a look at some of the tune files offered on Holdencrazy.com
    (Just remember to use a pre-2004 set of Injector Tables).

  5. #15
    Lifetime Member Cougar281's Avatar
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    What are the benefits of the 2002 OS over the 99 OS, and would I be able to use my Tech2 and TIS to flash in a cal from a similar 2002 vehicle?

  6. #16
    Joe (Moderator) joecar's Avatar
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    My understanding is the 2002 OS has some "corrections" in it, but I'm not sure what exactly...

    Also, the 2002 OS allows you easily jump to COS5 if required.

  7. #17
    Lifetime Member Cougar281's Avatar
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    I've been doing some reading, and I see posts where people say to copy all the tables from teh 99 OS into the 2002 OS... Why is this if you're going from a 99 LQ4 OS to a 2002 LQ4 OS (for example)? As long as you're using a new OS from the same "model" motor, shouldn't the new tables work just fine, if not better?

  8. #18
    Joe (Moderator) joecar's Avatar
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    If the same model motor has the same calibration values then it should copying tables is not required.

    In the day, the typical 2002 F-car file upgrades were:
    1999/2000 F-car file: required copying of some tables.
    2001 F-car file: did not require copying.

  9. #19
    Lifetime Member Steve Bryant's Avatar
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    I have a 2000 Yukon XL (K2500 4X4) and the 1999 and 2000 trucks had cast iron heads. I've ported mine, but the 317 and 035 aluminum heads are better flowing in stock form versus the cast iron originals. Essentially, the 317 and 035 aluminum heads are the 243 LS6 heads with 72 cc combustion chambers. One big difference in between the 1999/2000 trucks versus 2001 and after is the cam. The cast iron head LQ4s had a reverse split 191/190 cam like the 4.8 and 5.3 L engines. The aluminum head LQ4/LQ9 had a 196/207 cam like the F body cars. All can be improved with a good tune. These trucks did not have power enrichment enabled. I think conservatively, you could get 20 to 25 more HP with a good tune and no other change. I've run a 212/218 cam that I recently had reground (too much intake duration, torque band too high for a heavy truck) to a 206/212 with a 112 ICL that I'm going to install in my stroker engine that I'm finally ready to finish.

    I do recommend doing a full flash to a 2001 or later OS. I'm currently running OS 12208322 because I could download it from http://www.holdencrazy.com/EFILive/stockTunes.php. I uploaded my 2000 stock tune a few years ago and it is on the same web page, but you really want to get away from the back up VE table. BTW, I was running COS 3 for about three years, but I think that running full closed loop is better for a daily driver that is operated in a place like Wichita where we have 10 degrees F in the winter and 110 F in the summer and I go from 800 feet above sea level to the Rockies at 10,000 feet MSL.

    On another point, how could I find out what OS is in like a 2002 K2500 Suburban or Yukon XL and how could I get a .tun file to use as a starting point. I'm reworking my tune now, but I'd just as soon have the latest and greatest version for a 512 k PCM. I've looked on used car lots for a couple of years now, to no avail.

    Cougar281, I'll be glad to help you in any way that I can.

    All my best,

    Steve
    Last edited by Steve Bryant; February 13th, 2010 at 04:28 AM.

  10. #20
    Senior Member Hyper99's Avatar
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    Yeah, I played around with the 02 OS I bit and what I can remember was that it was not a cut and paste deal across the whole tune. You have to go thru the whole tune completely. There were a couple of tables that the values were inverted from the 99 to the 02. (might just have been my stock OS )

    I spent most of my time working with the stock OS and tune just modifying it as I go based on the mods that I've done. It really seems to breathe well with the cam and the blower now. Adding the cam seemed to piss off the computer in regards to KR.....I had to turn the sensitivity of the knock sensors way down....I have read that the 02 OS did a better job of controlling this....One other reason to update if this is actually fact....

    I am pretty happy with the tune in OL, but have been playing around with the MAF to get good drivability to pull my trailer in CL (and to pass emmisions) The 02 tune does not have the backup VE and two spark tables, less work when setting up the autove tune for SD. I'm considering going back thru the tune again and starting with the 02 OS because I eventually wanted to go to COS5 for the blower, but I was not really done messing around with the MAF yet to see if I can get the fueling table and the trims to agree....

    The truck seemed to really benefit from some trans tuning as well.....it was a bit lazy stock IMHO- pulling up the shift points, among other things, made for stronger shifts and felt better based on the seat of the pants dyno.....Joecar put together some really good info on trans tuning....Very helpful...

    Just my .02 - let me know if I can help.
    99 Silverado 2500 Extracab Longbed
    33" BFG's - American Racing Rims

    Custom Dual Upper console gauge mount w/Autometer Sport Comp - Pyro, Oil Temp
    Autometer Sport Comp Boost/Vac in Custom Hypersonic Gauge Mount in dash

    LS-1 6.0L w/AFR 205cc Street Heads
    Vortech V2 blower
    42# Injectors
    Comp Cam - Custom Street Grind
    TTS Catback Exhaust
    Innovate LC-1 Wideband O2
    Tune and Trans mods via EFILive V1-V2

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