ACIS mod by request

[sanengo]

Brian here is the ACIS mod in a nutshell, I'll add to it later. This mod is meant for the 3VZ-FE engine, but may apply to 1MZ engines too.

Background:

Basically, the ACIS is a valve powered by an actuator operating by vacuum pressure that closes when engine revs past 3900rpm to give better high end power. When it's open, it theoretically gives more low end torque, but the 3VZ-FE engine is already very torquey. Furthermore, when the valve is open, the air is very turbulent and may actually limit airflow. So by making the ACIS close early, it will allow the engine to produce a smoother powercurve delivering peak power sooner. More power under 3900rpms and 50%+ TPS. It may be even more noticeable if you did some intake porting.

How To:

1. Disconnect the VSV electronic valve gate. The brown/orange plug on top of your crank case.
2. Disconnect the long vacuum tube going to your vacuum tank, which is located under your battery
3. Unplug the small length of vacuum tube that goes from your ACIS to the VSV and replace it with the long tubing that was originally going to the vacuum tank.
4. Plug the other end of the long tubing to the first vacuum nipple on top of the TB closest to the driver. (the nipple is pointing to the passenger direction and is connected to your EGR)

*note*I have a 3VZ-FE engine, it may be different for the 1MZ. Also, if you don't do a T-junction, you will have to disable your EGR. If ever you do smog checks, please reconnect all tubing to their stock positions.

5. Put a screw into the tubing you took out of the TB nipple to block it. Then put the small length of tubing that was originally going from the ACIS to VSV into the empty nipple on your vacuum tank and put a screw on the open end of it to block it.
6. Make sure all tubing is secured and not loose. Reset your EFI fuse from the fuse relay box. (Take it out for 1 min and put it back in)
7. Crank the car and push the butterfly lever that opens your TB valve and make sure the ACIS actuator closes almost immediately after pushing the lever.
8. If it still closes around 3900rpm, you chose the wrong nipple. There are 2 vacuum lines running into your EGR, one of the 2 will produce a stronger vacuum. For me, it was the inner most nipple.

Pics: Thanks to Brandon (Toysrme) from TN for mod and pics.


That brown connector is the VSV valve.


Tube goes from ACIS directly to vacuum nipple on top of your TB.

*Do not try this mod if you aren't familiar with your engine! If you screw up, it's not my fault, I'm only providing the directions to performing this mod, I am NOT advocating it*

*Once you put a screw into the tubing, it can't be reused, please purchase replacement tubing*

If you have any questions, reply or pm me.

[Brian R.]

Good post. Thanks alot.

Here's another discussion.

http://www.toyotanation.com/forum/sh...6&page=1&pp=15

It looks like they perform a different mod than what you describe.

[sanengo]

Originally Posted by Brian R.

Good post. Thanks alot.

Here's another discussion.

http://www.toyotanation.com/forum/sh...6&page=1&pp=15

It looks like they perform a different mod than what you describe.

That thread has some incorrect information. The ACIS valve actually CLOSES after 3900rpms and OPENS before 60 degrees TPS. The TN thread is pretty old, and they probably got the information from Haynes, which reversed the ACIS position.

EDIT: It is a good idea to clean the intake by degreasing it, but the vacuum mod will nullify the grinding mod as the ACIS will remain closed most of the time.

[Brian R.]

It seems like they concentrate on grinding the valve body/butterfly instead of changing vacuum connections to modify the valve vacuum.

[sanengo]

Originally Posted by Brian R.

It seems like they concentrate on grinding the valve body/butterfly instead of changing vacuum connections to modify the valve vacuum.

The grinding is really to clean the valve of carbon diposites to regain lost power, instead of gaining more power. They merely grazed the surface of the valve body, because if too much grinding takes place, the valve wouldn't be able to shut and you lose all of your high rpm power.

[sanengo]

That dyno shows 2 humps in the torque curve due to the shutting of the ACIS valve, there is a second hump.

[Brian R.]

Is that dyno run before or after the mod?

[sanengo]

That is a before. Notice there are 2 humps in the torque graph. What we want to do is eliminate the valley between the 2 humps. I did some further testing with different vacuum nipples on the TB and I found that you get the most power with the vacuum that closes the ACIS at 2800-3200 rpms. The first one I mentioned closed the ACIS way too fast and did cut some initial power.

[Brian R.]

Your dyno run graphic link is broken

[sanengo]

Rehosted. I'll see what the response from people are who try this mod. If it's positive I'll post some more advanced ones.

[BlueFusion6851]

I'd like to do this... Unfortunately, I am not very understanding on where the VSV and EGR are located and the pictures are the killer red x. Rehost, please?

[BlueFusion6851]

bump

[sanengo]

Rehosted, if there's more interest in performance mods please pm me, I have a few more up my sleave.. i hope.

[Brian R.]

Post them in this forum for the FAQ thread