VVTi Throttle problem

Does anyone know anything about the "Drive By Wire" throttle system the VVTi engine seems to have adopted? Why does it push my foot up off the accelerator when the car is accelerating hard? It does it just as it changes gear, first to second. The car is a MKIV Facelift VVTi tiptronic.

I've had a couple of VVTi Supras and I've never experienced what you're describing.

TBH, I can't see how it could possibly do it.

The DBW system uses independant Pedal Position Sensors and servo's to open the throttle...nothing can force the pedal up. If it really is happening I'd suggest it's not ACTUALLY the throttle that's at fault, unless the throttle has become so bunged up with crap that it's no longer able to work independantly!

EDIT to say that my experience of the Throttle was on a manual. I don't know if the tiptronic has other bits to it. I'd expect the throttle plate to shut the throttle a bit to change gear...but you shouldn't feel or know about it.

I've never experienced that either. Im not a techie, but the only thing I'm aware of that can move the pedal is the return spring or cruise control if fitted...not likely though, is it. Odd.

I've had this car for 9 years, It's amazing! Were your VVTi's pretty much standard? I've done a few mods to mine and perhaps the car just doesn't like it? I've done the following: Blitz exhaust, Blitz boost controller, 2 new stage 3 hybrid turbo's, 1.6mm HKS head gasket, Blitz blow off Valve, Blitz front mount intercooler, a fuel cut defender, and am about to fit 2 decat pipes, as I can't seem to get the boost past 1bar, and an uprated fuel pump. Any suggestions?

I put a single on mine and the throttle never moved unless provoked by me!

I think we need more information - take the mats out and re test.

I've had this car for 9 years, It's amazing! Were your VVTi's pretty much standard? I've done a few mods to mine and perhaps the car just doesn't like it? I've done the following: Blitz exhaust, Blitz boost controller, 2 new stage 3 hybrid turbo's, 1.6mm HKS head gasket, Blitz blow off Valve, Blitz front mount intercooler, a fuel cut defender, and am about to fit 2 decat pipes, as I can't seem to get the boost past 1bar, and an uprated fuel pump. Any suggestions?

I ran with CATs and a boost controller hit 1.2 no probs. The VVTI FCD does have specific wiring requirements ie its different to earlier Supras maybe its wired up wrong? Mines same spec as yours but with the CATs already out and it goes very well

Umm... no ghostly throttle pedal here either.

Possibly a physical pedal assembly problem? Dodgy spring (or however it returns?)

Do VVTi's still have a kickdown switch under the pedal? Could be that>

Do VVTi's still have a kickdown switch under the pedal? Could be that>

I believe not. All done by TPS.

wierd, I get throttle intervention sometimes but it's at the manifold, as the cable is just that; a mechanical cable. maybe your car is so fast it forces your foot off the pedal!