Results 1 to 4 of 4

Thread: Cam "parked" position? Cadillac ATS LTG - Are the Numbers in Cam Table Retard?

  1. #1
    Tuner in Training
    Join Date
    Jun 2020
    Posts
    38

    Cam "parked" position? Cadillac ATS LTG - Are the Numbers in Cam Table Retard?

    I am taking the HP Academy variable cam tuning course and was hoping someone much smarter than me can chime in and explain the parked position of these cams, and also what the numbers in the intake and exhaust cam tables mean.

    I read up on Gen IV and V V8 motors which are obviously different as they only have one cam with intake and exhaust lobes on it. If I understood correctly, the parked position of the cam (with no input from the ECU) is fully advanced, and the cam can only be retarded (as it relates to engine crank degrees).

    Is the LTG intake cam fully advanced when in the park position and can only be retarded?

    Do the LTG cams work the same way as the V8 motors? Meaning, even though I see positive numbers in the cam table, this is degrees of retard?
    For instance, if I seen 19 degrees in an intake cam table, does the mean the ECU is commanding 19 degrees or retard (referenced in engine crank degrees).


    Now what about the exhaust cam?
    Is the LTG exhaust cam fully advanced when in the park position?
    Do the numbers in the exhaust cam table correspond to degrees of retard?

    Thanks for anyone who can explain this in a way I can wrap my brain around it.

  2. #2
    Senior Tuner cobaltssoverbooster's Avatar
    Join Date
    Dec 2008
    Location
    Nevada
    Posts
    4,452
    dual cam motors fully advance the exhaust and fully retard the intake at park position.
    The larger the value in the cam table, the more retarded the exhaust cam gets and the more advanced the intake cam gets. The computer is designed to command overlap and default into max separation when in limp mode (parked positions).
    2000 Ford Mustang - Top Sportsman

  3. #3
    Potential Tuner
    Join Date
    Feb 2017
    Posts
    9
    Quote Originally Posted by cobaltssoverbooster View Post
    dual cam motors fully advance the exhaust and fully retard the intake at park position.
    The larger the value in the cam table, the more retarded the exhaust cam gets and the more advanced the intake cam gets. The computer is designed to command overlap and default into max separation when in limp mode (parked positions).
    This is definitely true for the earlier ATS models, but not the later ones that share (mostly) the ecm with the Camaros. For those later models, positive numbers mean advance for both cams, at least based on the literature.

  4. #4
    Advanced Tuner
    Join Date
    Aug 2016
    Posts
    386
    The "literature" is wrong then.

    On all LTGs, regardless of year, and HFV6 early gen engines (LF1, LF3, LF4, LFX, etc.), it's as cobaltssoverbooster said. 0* on the exhaust cam means fully advanced and 0* on the intake cam means fully retarded. As the angle increases on the exhaust cam, the cam timing retards, and as the angle increases on the intake cam, it advances.

    On the LUJ/LUV (1.4T MPFI and probably other engines from that family as well like the 1.8L NA, etc), that is NOT the case, however. Both cams are fully advanced at 0*, and they both retard as the angle increases.