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Thread: Anyone with a 90mm TB inside please

  1. #1
    Senior Member
    Join Date
    Jun 2005
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    113

    Default Anyone with a 90mm TB inside please

    Is anyone having trouble getting the blade to 100% open on DBW cars?

    Please see this thread: http://www.performancetrucks.net/for...&page=10&pp=10

    In case the link gets messed up, the discussion starts on page 10, post 99.

    It appears to me that the there is a TPS voltage issue, or that the voltage from the 90mm TPS is being misinterpreted by the TAC or the PCM (my vote is the PCM). Evidently HPT is looking into this and may be adding some tables to allow the conversion to succeed.
    Last edited by turboberserker; June 17th, 2006 at 01:27 AM.
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  2. #2
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    Oct 2005
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    Default

    The 02 TAC module seems to be getting along with the LS2 90mm TB even though the sensor outputs are different than those of the 78mm TB that the TAC module was designed for. Could be that the minimum/peak outputs don't matter as much as the correlation between them. The TAC module may ignore anything over or under the normal limits for the 02 78mm TB sensors.

    Although the TB does not physically open 100%, the PCM is commanding 100% and the TAC is reporting 100%. It does appear though that the 02 TAC module was designed to recognize respective sensor voltages of 3.5V(sensor 1) and <1V(sensor 2) as WOT while the LS2 TB reaches 3.5V before WOT(>4V is considered WOT on LS2).

    This could affect idle tuning as well if <1V(sensor 1)/3.8V(sensor 2) is considered fully closed by the TAC module, because the LS2 TB reaches these values somewhere before fully closed.

    Is it possible to log the LS2 TPS1 and TPS2 voltages along with the PWM of the TAC motor? I can't find anything that works. I would like to know the max TAC motor pulse width at WOT and the corresponding sensor voltages. I'm guessing that the PW plateaus before the sensor voltages peak/bottom. Then it would be nice to compare that to an actual LS2.

    Don't know if this can be addressed in the tune unless there is a way for the PCM to ask the TAC module to increase the PW at 100% commanded TP, etc. Providing that the TAC module is capable of doing so.

    I see that this is also being discussed on the SSR forum:
    http://www.ssrfanatic.com/forum/showthread.php?t=10880

    I also experience the REP mode issue at WOT but not every time. The DTC is MAP/TP correlation.
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