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Thread: shift rpms tis rpm or engine rpms

  1. #1
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    Default shift rpms tis rpm or engine rpms

    doing a 98 camaro with a stall converter and cam will not shift on 2 to 3. it worked fine with converter only car. now with cam it will not shift 2 to 3. on a log i took looks like it shifts off tis rpm not engine rpms.it seems like people are allways having problems with shifting. i can see where a loser converter would make things crazy because converters are tighter with lower gears. so the 1 and 2 shifts converter is more locked up so the tis rpm is higher in 2 gear tis rpms could eazly be lower making it not reching the set rpm shift point.hear is a log my vss shifts are set low so it uses rpms.my rpms are set at 5650 in the log looks like 1 to 2 shift 5650 @ tis and 2 to 3 tis never makes it there with out engine speed hitting limiter.i dont have the car right now to do more logs looking for ideas befor it comes back to be finished.also like to see if anyone has a log with a convert and pids tis,tos,tccslip,engine rpms and what there shift points are thanks
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  2. #2
    Joe (Moderator) joecar's Avatar
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    69Camaro,

    Are you running with the 4L60E...?

    The 4L60E doesn't have a TIS sensor, so the PCM computes the TIS based on how much it computes the TC to be slipping... I don't know how well TIS can be relied on... the 4L80E does have a TIS sensor, as do some 4L65E... but the PCM needs a connector and subharness for it...

    Maybe the PCM is following TIS for the WOT upshift (I don't know for sure)... but as you can see, TIS isn't a good RPM source.

    TOS is just the VSS sensors in rpm instead of mph.

    Try setting your 2->3 WOT RPM much lower (it may mean you have to set the 2->3 WOT MPH even lower... e.g. 40 or 30 mph)... say downto 4000 or 3500 rpm... you should then be able to get the 2->3 WOT shift... you then adjust it up from there until the log shows you shifting at the rpm you like regardless of its value in the tune file... e.g. 4900 may actually trigger the shift to occur at 5600, for example.

    Also, on the PIDs tab, remove a few pids... if you exceed 24 channels (indicated on the bottom on the PIDs tab), then each pid gets updated at 5 samples/second instead of at 10 samples/second that you would get with 24 or less channels (some pids occupy 1 channel, other pids occupy 2 channels)... e.g. remove PRND, TFMDES, FUELSYS, those aren't helping.

    Other comment: I don't know if TCCSLIP is showing good data.
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    yes it is a 4l60e whats wierd it shifted couple times with that tune at 6100 now doesnt i didnt know there wasnt a tis seen the pid so though there was. thanks for info guess i will lower shift points even lower thanks

  4. #4
    Joe (Moderator) joecar's Avatar
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    Also, if you changed the converter, do a CASE relearn so that the PCM can account for new/different rotating mass in its misfire algorithm.

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    ok after looking over log again and seeing pressure drop i add some trans flud thinking maybe it was sucking pan dry shifts fine now.now it shifts early had to rase vss to keep from shifting befor rpms are meet on shift points.thats backwards of what every one says to do lol

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    wierd you have to over fill a trans the dip sticks must be marked little off. older trans would over heat and burn up it they where to high 4l60e has to be over filled.

  7. #7
    Joe (Moderator) joecar's Avatar
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    You can overfill the 4L60E to about 1/2 inch above the hot full upper mark...
    but do check occasionally for bubbles in atf on end of dipstick... no bubbles = good.

    Do you have the stock pan & filter or the truck ones.

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    It Is stock sounds like needs a deep pan with longer pick up In It. I have heard of many f bodys eating 4l60e like 3 or 4 of them In one car I wonder If flud leavel Isn't the problem with some of them.

  9. #9
    Joe (Moderator) joecar's Avatar
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    The filter and seal are a bit tricky...

    the filter tube has to be all the way on into the seal or the filter rests on the pan, which may cause a restriction on the filter opening/pickup (same concept as motor oil pump pickup clearance to oil pan)...

    some people don't lube the seal, so the filter doesn't go all the way in (it takes more effort to push in, but it's made of plastic, so people don't want to break it);

    fluid level is probably the cause of repeated failures, the dipstick is the wrong length.

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