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The mkiv Supra Owners Club

Will I need a standalone ecu to run a Q45 throttle body?


HarleyFDMD
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I think I would disagree with the above, you are changing the MAP sensor figures substantially in relationship to a given throttle angle opening, and I would not be at all sure the stock mapping will happily cope with such big changes without falling back to some sort of safety map. I would take advice on a forum more specific to automotive ECU's. MOTEC, Syvecs, AEM, whatever, where the experts lurk.

 

 

EDIT:

 

I have just asked on the MOTEC forum, will copy any replies here, although as it's not a MOTEC specific question I doubt they'll bend over backwards to make a rapid reply.

Edited by Chris Wilson (see edit history)
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A post from a well respected expert:

 

"I think it would be best to beat him around the head with that 10x excessively large TB for the power he will be making.

 

I'd say it's bound to cause many issues unless he can re-tune the ecu."

 

I have always said these big TB's give throttle modulation issues, that's why Mazda with the FD3 used a small butterfly for low air flow modulation, with a slightly bigger area pairing for wide open throttle on a gear and quadrant. I recall Jonny's last VVTi supra with a huge US TB being terrible to drive as cruise to mega power was a few millimetres of throttle pedal depression. Bigger is not always, or even often, better.

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I recall Jonny's last VVTi supra with a huge US TB being terrible to drive as cruise to mega power was a few millimetres of throttle pedal depression. Bigger is not always, or even often, better.

 

i have heard this from a few members on larger throttle body on syvecs!

 

trd robs car drives like stock

 

 

on a side note the stock traction flap needs to be fully operational on an automatic as well for the transmission to function as it should

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Two sub £10 pressure gauges, one plumbed in before the TB, and one plumbed into a plenum tapping point, will show in minutes if you need a bigger TB. Just read the pressure drop across the stock TB. The ones I have checked, on even big power engines, suggest a bigger TB is not a worthwhile mod on 90% of modded 2JZ-GTE engines. And on those where one is required, and it is still used on the road, I would look at a dual body, with sequential operation, or one with a progressive throttle butterfly action, like on say a Porsche 928.

 

Too big a TB and plenum can give the bizarre effect of the car going faster when you lift off the throttle slightly at some steady state cruise throttle openings. It's quite unnerving and shows airflow is in a right mess.

Edited by Chris Wilson (see edit history)
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Just checked back at this! Thanks for all the help and advice chaps. Although I must admit some of the rather in-depth technical stuff does go over my head.

My position is this:

Na t, with a custom ffim (made to a very high standard) that has an oem throttle body compatible flange welded on. However I think the oem throttle body on a ffim will cause problems due to the throttle cable facing the wrong way?

I figured using a q45 would be simpler and be better aesthetically, using a greddy tps adapter. I pressured it would also be better functionally too? Perhaps not?

The car will be being mapped obviously going na t so that part won't be an issue

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Yeah a front facing plenum.

No my concern is not that the throttle cable won't reach, but that the throttle cable will be pulling from the wrong side of the throttle body. Hard to explain but if you think of an na manifold and throttle body the throttle cable is in front of the throttle body. So if I mount it onto a front facing plenum the throttle cable will have to loop round the edge of the engine bay and onto the front of the throttle body

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