took apart my IM today...

[jamesmx3]

right so I stripped the vacuum hoses off as one piece with the fuel rail, then split the IM. I've never slipt the IM before and I was wondering why there is a vacuum system, then I saw the four butterfly valves that are controled by the vacuum system. Whats the reason for the butterfly valves, looks a bit like 4 TBs??

The other thing I wanted to know was is it the EGR that makes the IM so dirty inside, that and the two hoses coming out of the camcover. Is there any way to keep it cleaner??

[RS_OBD'oh_2]

Ya, that would be the VRIS. And yes... EGR is the devil. Makes you wonder why you even bother to put an air filter on.

[jamesmx3]

If you block the egr that makes it run rich right? Like you say about the air filter, it makes port and polish seem a bit pointless too then right or does the crap not stick as much if it's polished?

Can you expand on VRIS? I take it it's some sort of system that at full throttle or something opens to give more air to the engine?

Cheers

Edit: just googled vris and found a good explanation.

[mitmaks]

I was never aware that there's VRIS on 4 bangers....

[jamesmx3]

from what ive read, the US cars didnt have it, my UK B6 has so does my BP.

[lowflyinmx3]

Wasn't it VCIS on the 4 cylinders?

[RS_OBD'oh_2]

that may be. VICS or VRIS.. one or the other.
Found:
We are not listed.. but this sounds like it.

Prototech Special Feature: VICS (Variable Intake Control System)


Honda has been touting VTEC for a couple years now. Toyota recently introduced VVT-i. Mazda has some of their own technology up their sleeve. VICS. It's not variable valve timing (Mazda's variable valve timing, S-VT will debut soon), but it is something worth talking about. VICS is used to increase torque at lower RPM's and increase horsepower at higher RPM's. Here's how it works:

On VICS equipped engines, there are two intake runners for each cylinder.

The primary intake runner is a long, thin tube in which the intake air passes through. This allows a strong stream of air to blast into the cylinder, helping low-end torque.

The secondary intake runner is a short, fat tube. This allows a large volume of air to be sucked into the engine, increasing high-end horsepower.

At lower RPM's, the engine does not provide enough suction into the cylinders, starving the engine of much needed oxygen. The skinny tube helps blast the air into the cylinder for more oxygen. At higher RPM's, the engine has plenty of suction but the intake runner is too small to provide the oxygen it needs. The short, fat tube allows plenty of oxygen to be sucked in.

In the Protegé ES, the primary runner is open from idle to 3,500 RPM. Between 3,500 RPM and 3,800 RPM, the engine computer begins closing the primary runner and opening the secondary runner. Above 3,800 RPM, the engine breathes with the secondary runner. The Miata makes the transition at a higher RPM, while the 626 and MPV makes the transition at a lower RPM.

Most engines have a single intake runner per cylinder that is compromised between low and high RPM and has a narrow powerband. With Mazda's variable intake design, the engine enjoys a wide powerband.
Here are the vehicles which use a form of Mazda's VICS:


1991-1995 Ford Escort GT 1.8L

1994-1997 Kia Sephia 1.8L

1990-2000+ Mazda Protegé 1.8L

1993-1997 Ford Probe GT/Mazda MX-6 LS 2.5L

1993-2000+ Mazda 626 2.5L

1994-2000+ Mazda Miata 1.8L

2000+ Mazda MPV 2.5L (Ford Duratec)
You'll also find it in Ford's Duratec engines and the Yamaha-tuned Taurus SHO engines (V6 & V8). Ford's ZETEC engines (Escort ZX2, Contour 4cyl, Focus) use variable valve timing on the intake valves (like the Civic EX). Mazda will introduce their variable valve timing, entitled S-VT (Sequential Valve Timing), to the U.S. for the 2001 model year with the Miata and the Protegé.

-Special Thanks to jstand6@yahoo.com" onclick="window.open(this.href);return false; for providing this information!