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Thread: Can the 98 2 bar SD OS use a 3 bar map sensor and scale?

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    Can the 98 2 bar SD OS use a 3 bar map sensor and scale?

    Basically I am stuck with a 98 POS PCM. I am currently running the 98 2 bar OLSD OS with a 2 bar GM MAP sensor and it worked great for the stock bottom end turbo build. Now I'm going forged and want to turn the boost up over 20 psi. Is it possible to fudge the VE and use a 3 bar MAP sensor? Basically just reduce the resolution by 1/3. Will this screw anything else up?
    98 Z28 370 LQ9 w/ TH350, FTI 4800 Stall, OLSD, NW90 TB, 80# Motron Inj, AFR 225's, 231/231 .624/.624 114, Mamofied FAST 90 Intake, PT88 Front Mount w/ 4" DP dumped before the Strange S60 w/ a 3.73 gear

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    How about using a 4 bar map sensor and splitting it in half?
    98 Z28 370 LQ9 w/ TH350, FTI 4800 Stall, OLSD, NW90 TB, 80# Motron Inj, AFR 225's, 231/231 .624/.624 114, Mamofied FAST 90 Intake, PT88 Front Mount w/ 4" DP dumped before the Strange S60 w/ a 3.73 gear

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    Should work fine if you scale the other proper parameters. All the MAF guys are doing it now.

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    What are the other proper parameters? Just pop in the 0-5v 4 bar map and cut everything that references the MAP entry and exit in half and rebuild the VE table? Or is there something else?
    98 Z28 370 LQ9 w/ TH350, FTI 4800 Stall, OLSD, NW90 TB, 80# Motron Inj, AFR 225's, 231/231 .624/.624 114, Mamofied FAST 90 Intake, PT88 Front Mount w/ 4" DP dumped before the Strange S60 w/ a 3.73 gear

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    Quote Originally Posted by LosLS2 View Post
    What are the other proper parameters? Just pop in the 0-5v 4 bar map and cut everything that references the MAP entry and exit in half and rebuild the VE table? Or is there something else?
    Not sure of all of em. There is a thread in the gen IV section right now. Seems its on Greg's DVD tho (I guess Im gonna have to buy it one of these days)

  6. #6
    Advanced Tuner blownbluez06's Avatar
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    Curious why you wouldn't use a 2-bar sensor. If you scale it, you're losing resolution on your VE and other tables.
    Hsquared racing engines RHS 427, Procharger F2, Moran Billet Atomizer injectors, Alky Control,Mast LS7 heads, Nitrous outlet kit,Tilton quad disc clutch, DSS shaft, RKT56 ZR1 trans, RPM Quaife diff. Built and tuned by yours truly.

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    Quote Originally Posted by blownbluez06 View Post
    Curious why you wouldn't use a 2-bar sensor. If you scale it, you're losing resolution on your VE and other tables.
    Hes maxed out the 2 bar and hes got a 98 PCM (only 2 bar support)

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    was thinking MAF still. Yeah you should be ok halfing all the values referencing MAP.

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    Advanced Tuner blownbluez06's Avatar
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    Quote Originally Posted by slow67 View Post
    Hes maxed out the 2 bar and hes got a 98 PCM (only 2 bar support)
    What kind of F/I are we running? You can tune past 2 bar with a centrifugal supercharger.
    Hsquared racing engines RHS 427, Procharger F2, Moran Billet Atomizer injectors, Alky Control,Mast LS7 heads, Nitrous outlet kit,Tilton quad disc clutch, DSS shaft, RKT56 ZR1 trans, RPM Quaife diff. Built and tuned by yours truly.

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    Tuner gold98Z28's Avatar
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    y not just repin the connector for the 99up pcm?
    98 Z28m6,ramVDS,lakewood LCA,sphon SFC,NOS 125shot,HPtuned LQ4.045milled heads,224/228 581/588 comp cam,fast toys lid,ported 85maf,ls6 intake,long tubes with custom exhaust

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    Quote Originally Posted by blownbluez06 View Post
    What kind of F/I are we running? You can tune past 2 bar with a centrifugal supercharger.
    I'm running a front mount turbo setup. Regardless, how is boost from a blower different than from a turbo?

    The limitation is that the only custom OS available for the 98 PCM is a 2 bar. 99 and up PCM's have alot more options available to them.
    98 Z28 370 LQ9 w/ TH350, FTI 4800 Stall, OLSD, NW90 TB, 80# Motron Inj, AFR 225's, 231/231 .624/.624 114, Mamofied FAST 90 Intake, PT88 Front Mount w/ 4" DP dumped before the Strange S60 w/ a 3.73 gear

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    Quote Originally Posted by gold98Z28 View Post
    y not just repin the connector for the 99up pcm?
    I've considered that and am also considering the megasquirt II. At this stage of the game, I've just about outgrown the stock PCM.
    98 Z28 370 LQ9 w/ TH350, FTI 4800 Stall, OLSD, NW90 TB, 80# Motron Inj, AFR 225's, 231/231 .624/.624 114, Mamofied FAST 90 Intake, PT88 Front Mount w/ 4" DP dumped before the Strange S60 w/ a 3.73 gear

  13. #13
    Tuner gold98Z28's Avatar
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    if you have the coin, then go aftermarket. but you can do alot with a repin and a 3bar OS.
    98 Z28m6,ramVDS,lakewood LCA,sphon SFC,NOS 125shot,HPtuned LQ4.045milled heads,224/228 581/588 comp cam,fast toys lid,ported 85maf,ls6 intake,long tubes with custom exhaust