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Is the MAP table related to the size of the engine

This is a discussion on Is the MAP table related to the size of the engine within the Computer & Tuning forums, part of the LSx Technical Help Section category; I have replaced my LS1 engine with an LS2 short block and capped it of with what I had on ...

  1. #1
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    Smile Is the MAP table related to the size of the engine

    I have replaced my LS1 engine with an LS2 short block and capped it of with what I had on top of my old LS1. I am conducting the tuning now and would like some guideance on the MAP table. The little bit of data logging that I have done, tells me (on average) I need to reduce my LTFTs by 15%, and I am convinced that I should use the MAP to do so. Is it a coincident that the 402 is 15% larger than the 347 LS1?

    And does anyone have a MAP table for a 402 that they could send me? I want to compare it to my LS1 MAP table.

    And I think that i need to update my signature stuff.

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    So, I suppose nobody on this board has replaced their LS1 engine with a larger displacement LSx engine and tune it themself. If yes, please jump in here, what did you do when you tuned it.

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    TunedbyFrost.com Tuner Frost's Avatar
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    update the displacement/cyl in the general section (if HPT, if EFIL, I dunno) before you start tuning.

    If you have a MAF hooked up, you can change your VE all day at cruise and it won't do a thing. There are tons and tons of tuning stickies that have these basics such as First tune VE with MAF disconnected and failed out, then reattach the MAF and do it's cal. IF you are riding around with a MAF hooked up, most all of your fueling is coming from it.

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    Frost, thanks for the reply. (you're over here too) For starters, I change the fuel injector constant for the 39#/hr FAST injectors that I installed. And as you recommended, I changed the disp/cyl value. After these two straight forward changes, I started to tune idle, then cruising. While idling the LTFTs went thru the roof immediately. Since I had tune the GMAF dead nuts correct before I blewup my LS1 engine, I felt that the MAF table had to be correct and it was the MAP table that needed tuning. First time thru the MAP table, I multiplied every cell by 115%, then another 105%. This brought most FTC LTFTs to near zero.
    What do you think of this approach?

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by Doc99SS View Post
    Frost, thanks for the reply. (you're over here too) For starters, I change the fuel injector constant for the 39#/hr FAST injectors that I installed. And as you recommended, I changed the disp/cyl value. After these two straight forward changes, I started to tune idle, then cruising. While idling the LTFTs went thru the roof immediately. Since I had tune the GMAF dead nuts correct before I blewup my LS1 engine, I felt that the MAF table had to be correct and it was the MAP table that needed tuning. First time thru the MAP table, I multiplied every cell by 115%, then another 105%. This brought most FTC LTFTs to near zero.
    What do you think of this approach?

    Yessir I'm here

    If the MAF is hooked up, all you can really change on the VE that has direct impact on fueling trims is the idle area. By 1600-up it's almost all MAF. Those granatelli units are all over the place cal-wise. You will notice that you can add big %s in the area above 1600 and your trims won't change; if you add to the MAF table they will though. Of course if the MAF is unhooked and failed out, trims come directly from VE at that point.

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    1) If I get the P0101 MAF error code, does the PCM go into speed density and therefore get all of its fueling from the MAP table (plus the STFTs & LTFts of course)?

    2) So, if I simply unplug the MAF, I will be doing speed density tuning? I guess the answer is: YES (from your message above).

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    Senior Member mrr23's Avatar
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    1) it will default to the secondary VE table.

    2) yes. i set my MAF fail frequency to 1000 just to make sure.

  8. #8
    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by mrr23 View Post
    1) it will default to the secondary VE table.

    2) yes. i set my MAF fail frequency to 1000 just to make sure.

    +1

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