ACIS - getting rid

[jimgreen]

The mixture has velocity going into the chamber, the valve suddenly closes, the mixture hits the valve. A pressure wave bounces back up the intake. If you time the pressure wave right, you can have a wave help push some mixture in as the intake valve opens. (I could fill a post about it, but that's all you will ever need to know.)
The valve is open normally. Now Toyota says to "promote low end torque". This is a load of crap & anyone supporting it has never dynoed back to back. it is left open to DECREASE power & DECREASE fuel consumption!!!


Immediately after the throttlebody plate, the UIAC

In reality there are three things you can do:
1) Delete the vacuum canister, VSV, and hook the ACIS to the ports on top of the throttlebody. Technically, the port marked P opens it at any throttle above around 1000rpm, but some other 3vz-fe owners tell me theirs is sporadic. neither mine, nor Seans has had a problem.
OR
You can also hook the ACIS valve straight to the vacuum canister. As soon as the canister has vacuum -> flap opens & stays open!
2) JB weld, or braze the flap shut.
3) Cut the runners off your intake & weld an aluminum box + throttle body standoff on the runners. (Or JB weld. JB weld works well with aluminum. They expand at the same rate! You can fix engine heads with this after bad porting...)
The great Tony Leung's work (Tony the Tiger - hugest 1mz-fe)

If what the tuning guide says, and the ACIS doesn't give you torque, how many people have got rid? I quite like the chopping option.

[lodgeman]

i dont have mine removed but i do have the acis open as soon as the throttle is pressed!just bypass all the valves straight to the p port i think on the throttle body.

[loadswine]

It does give it a mean old sound Alan.:thumbsup:

[jimgreen]

Has anyone done dynos to prove that it doesn't give a torque increase?

[Paul Woods]

i have issue with the quotes in that opening post,by the way who originally posted that?

For a start the ACIS does promote low end torque,i know because ive run them with and without the ACIS ,theres a definate kick in the pants low down WITH the acis.

Also he says simply hook it up to the throttle body and the ACIS will always stay open,this is complete and utter nonsense!

Why? yes the acis will see vacuum from the manifold at idle and up to around 4000 rpm,but after that the vacuum drops right off,so the acis would shut again at high rpm right when you really dont want it to!

How do i know this? the TRD supercharger relies on the lack of vacuum at full throttle to release its bypass diaphragm so the charger kicks in....its plumbed directly to the manifold BEFORE the charger.....so at idle and anything below full throttle theres vacuum holding the bypass open and the SC doesnt work.....as engine revs rise the vacuum gets less and less until the diaphragm lets go and the bypass closes letting air only enter the SC.

So this idea of simply routing the acis to manifold wont work at high rpm... this is why toyota fit the vacuum cannister in line on the acis system so that the diaphragm remains pulled when theres not enough vac in the manifold.

I have tried all sorts of tests with the ACIS and theres not a lot of difference either way with it,i prefer to keep it to aid the low end torque.

[Paul Woods]

re read the quote and yes hooking it straight to the vac cannister would work but why would you want to?

[jimgreen]

It's from this guide Paul

Toysrme's 4vz-fe Tuning guide (http://www.mr2.com/forums/mk-2-v6/Toyota-MR2-1899-toysrmes-n-3vz-fe-tuning-guide-applies-all-n-v6s.html?vbseourl=mk-2-v6/Toyota-MR2-1899-toysrmes-n-3vz-fe-tuning-guide-applies-all-n-v6s.html)

[Paul Woods]

odd because that chap does know his stuff,maybe he just made a mistake with that particular comment about hooking it straigh to the TB

[jimgreen]

He seems to know what he's talking about yeh. Aside from the comment about hooking it up to the TB, has anyone actually RR'd ACIS vs no ACIS?

[tom1mr2]

Tried this today and put it back to standard because feels much better all round so would not really bother with it.

[Paul Woods]

agreed tom,its much better to have the acis working,we found a distinct power increase at lower rpm with it.

[biteme]

Paul, was it actual power or perceived power? I mean - was it quanitified on a dyno?

[OlberJ]

Butt dyno?

[tom1mr2]

Theres a big difference on the road johnny not as much punch at 4k and felt slow on bottom end up to that, feels great again now, will be trying the afm mod tomorrow if i get time.

[biteme]

hmm. fair play that man :)

[weegaz22]

or you could just junk it all and stick 6 ITB's on it :mrgreen:

[biteme]

and some extreme cams and 13:1 pistons? :P

[Garbe]

will be trying the afm mod tomorrow if i get time.

Tom let us know how you get on with it - number of clicks etc
I think mine's running really rich and want to get this done soon

[tom1mr2]

Yeh same here mate runs really rich and slow when cold but when warm flys!

think i am going with 5 clicks to be safe i no you can do between 3-7 but don't want it running to lean.

[OlberJ]

Lodgeman has done this for sure, have a word with him, think he's running 6 clicks fine.

[Garbe]

Mines really sluggish now the weathers turn colder. it feels like it does'nt want to rev past 2.5k (I think its to protect engine/gearbox as set up in the camry)

[tom1mr2]

Yep same here last couple of mornings i have left it ticking over to warm up thinking the afm mod will help a lot.

Will let you all know anyway :)

[Peebs]

Tried this today and put it back to standard because feels much better all round so would not really bother with it.

I tested throttle body hookup quite some time back, on my 6'er and the usual "power" just felt "flat". You could tell the potential power was still there, but you could also feel that it was being restricted. Then read about the "straight to vac canister" method, so tried that - felt exactly the same really, even tried the tb again, just to make sure. Yep I was right - still crap.
Conclusion - Toyota didn't spend millions of Yen on designing it for nothing - don't mess with it !
....um okay, just get the bugger out to clean it now and again :)

[Paul Woods]

butt dyno mr quimberson :thumbsup: