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Location:
Lost in the K hole
Registered:
May 2002
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TPS signal w/ throttle body upgarde
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Sat, 12 April 2003 15:43
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ok,
say im upgrading my throttle body from 60mm to 80-85mm...
what can i expect to have to do with the TPS? obviously the 'load' experienced by the engine at a given % of throttle opening will be greater with the new, larger throttle body, but this wont be reflected by the TPS - which will just pump out the same load signal it did stock for that given butterfly condition.
With my new t/b setup, it might be possible to mount the TPS to another part of the throttle cable pulley/tie rod system (actually separate from the throttle body) such that the TPS moves on a different rate curve than the throttle butterfly itself - ie move more quickly than the butterfly initially, then slows down in the later part of the butterfly motion. (i hope that make sense).
this would make the TPS more 'open' than the actual throttle butterfly at lower butterfly deflections (thus simulating larger load), and later at WOT, the TPS would be at WOT anyway, which is just fine.
does this make sense??
anyway... i gues the question is, have ppl had issues with TPS signals with throttle body upgrades in tha past, and how did you overcome them??
cheers
ed
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: TPS signal w/ throttle body upgarde
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Sat, 12 April 2003 15:56
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Heya,
does it have AFM or MAP? either way, the load should be measured by the air flow (AFM) or manifold pressure. also depends if you have a switch or variable voltage type of TPS? does it have 3 or 4 pins??
this is a bit OT, but the Megasquirt uses the TPS for a couple of things, but not for load as such.
at more than 40%(ish) opening of TPS, the closed loop O2 is turned off.
when you open the throttle, the rate of TPS opening (in volts/sec) is used to determine the accell enrichment, and similarly the decel fuel cut.
apart from that, the TPS is not used for much, unless you are running an alpha-n system (but i doubt toyota would have that as stock ; ) ) which wouldbe based on TPS and RPM....
if you have switch type TPS, it will make no difference i suspect.
if you have variable TPS, then it might affect the accel enrichment squirt, but i don't think that the 'extra load for perceived TPS opening' will be that much of an issue..
as a side question, can you have too large a throttle body, apart from losing low throttle sensitivity?
Cya, Stewart
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Location:
Lost in the K hole
Registered:
May 2002
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