auto shifting early and wont down shift after manifold swap
12-03-2008, 05:41 PM
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auto shifting early and wont down shift after manifold swap My firend put a ported stock manifold on his lt1. After that it will shift at like 3000 rpm at wot and wont down shift. But if you manually shift it through the gears it is fine. any ideas?
12-03-2008, 06:19 PM
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OK I'm confused... Port stock INTAKE manifold, Exhaust manifold? If it's an intake, why did he port it? Won't help anything w/o ported heads. If he installed a bigger throttle body (doubt I have to explain what that is) then that would be why it's shifting wrong. Bigger throttle bodys (52, 54 and 58 are the sizes over stock) will need a tune to account for the more air flow and less amount of throttle needing to be open, which the trans thinks it needs less line pressure, which it actually needs more. Basically what XJS said, but in a computer controlled transmissions point of view lol So, get it figured out and STOP DRIVING IT TILL THEN 
I mean, unless he wants a new transmission, which isn't all that bad if he doesn't have to pay for it! Can get it built up then heh
I mean, unless he wants a new transmission, which isn't all that bad if he doesn't have to pay for it! Can get it built up then heh
12-03-2008, 07:21 PM
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12-03-2008, 07:48 PM
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Given the rarity of 92-93s (only T/V years), I'm sure it's not a T/V issue. But hey, more and more 93s have been showing up on the forums here, so it's possible his bud has one. I've yet to cross paths with a 92 Vette though! heh
12-03-2008, 09:16 PM
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its actually a lt1 in a third gen trans am. it has a 700r4 tranny. He got the ported intake manifold and a throttle body. he go it for free thats the only reason he put it on. Could it be somthing tps related?
