VCIS-less



  • Hi Guys,

    Polishing up the rocker cover at the mo and just found out that my VCIS vacuum pipe isn't even hooked up!

    Its covered up with electrical.

    Would anyone be able to take a quick peek under their bonnet and see what its hooked up to? Its the pipe with the broken green line on it, the bottom metal pipe at the back of the inlet manifold, it looks like its supposed to hook up to something on the driver side of the car

    Also, has anyone thought of hooking up a servo to the VCIS rod, so you can turn it on at the flick of a switch? i know it wouldnt make much difference, but, you know, just cause!!



  • VCIS? Dont you mean VRIS (Variable Resonance Induction System)?

    @4c9ecf0f8d:

    Variable Length Intake Manifold (VLIM) is an automobile engine manifold technology. As the name implies, VLIM can vary the length of the intake tract in order to optimize power and torque, as well as provide better fuel efficiency.

    There are two main effects of variable intake geometry:

    • Swirl - Variable geometry can create a beneficial air swirl pattern in the combustion chamber. The swirls help distribute the fuel and form a homogeneous air-fuel mixture which ignites without engine knocking. At low rpm, the speed of the airflow is increased by directing the air through a longer path with limited capacity (i.e., cross-sectional area), but the shorter and larger path opens when the load increases so that a greater amount of air can enter the chamber. In DOHC designs, the air paths are often connected to separate intake valves so the shorter path can be excluded by de-activating the intake valve itself.
    • Pressurization - A tuned intake path can have a light pressurizing effect similar to a low-pressure supercharger due to Helmholtz resonance. However, this effect occurs only over a narrow engine speed band. A variable intake can create two or more pressurized "hot spots", increasing engine output. When the intake air speed is higher, the dynamic pressure pushing the air (and/or mixture) inside the engine is increased. The dynamic pressure is proportional to the square of the inlet air speed, so by making the passage narrower or longer the speed/dynamic pressure is increased.

    Many automobile manufacturers use similar technology with different names. Another common term for this technology is Variable Resonance Induction System (VRIS).

    (WIKIPEDIA)

    I'm just guessing but I'd say theres no point having a switch. Bit wierd that yours isn't hooked up tho. What kind of milage are you getting and does your car feel sluggish in the higher revs?



  • sorry, i meant VICS, for the I4 mazda's (4 cyl.) we have to settle for Variable Inertia Charging System.

    Its a little valve that opens at 4750rpm and changes the way air enters the engine.

    apparently its makes a small difference



  • Ahh, I've never heard of that one before (you learn something new everyday) but a quick search shows that its basicly the same thing as VRIS so my previous post still stands :P Any flat spots in your acceleration?



  • well my car isn't running properly so the whole acceleration process is a flat spot in my driving experience!

    i've got it booked in for a service this wednesday so hopefully it'll be running sweet.

    My backbox has started rusting away from the pipe and since that, the car has kick in her. This has completely put me off doing the Probe manifold mod. Unless adding a CAI will make a difference cause at the moment im still running the stock airbox, and maybe a UDP would help?

    Any ideas?



  • UDP? Under Drive Pulley? Gods damn acronyms catch me out every time :lol: i'd start by getting that loose hose reconnected, it was there for a reason and barring any serious defects/mods to the engine I cant think why it's been disconnected (anybody feel free to jump in and correct me if Im wrong :oops: ) a CAI is a good idea cos the stock box suck big time, not a big job takes about a hour if you dont know what your doing :lol: but from experiance on a V6 it makes the car feel a lot better. Not sure about exact returns on a 1.6 tho, but I expect siilar results :D and it would probably be the cheaper than a UDP (if by UDP you mean what I think)



  • after a thorough look at the online manual and the engine bay, there are more problems then i thought!

    one of the lines from the fuel pressure regulator to No.1 PRC Solenoid valve is broken at the connector on the valve, and the VICS connector on the VICS solenoid valve is also broken

    Im guessing this means a trip to mazda for them to rip me off!

    Unless anyone knows someone breaking a 1.6 mx?



  • yep, under drive pulley! took me an hour to work what it stood for when i forst saw it!

    defo gonna have to get hoses sorted, just not looking forward to mazda ripping a hole in my wallet!



  • :shock: Barrrgh! Stay away from OEM (hehhe!) Mazda parts are well overpriced and you can get better stuff for less money from 3rd party companies. And dont use Mazda garages either (Mazda owned by Ford) the one and only time I took my 3 to a Mazda dealer they fucked it up. :evil: better to find a local garage that comes with a good recomendation from friends/family.

    Example (bear in mind this was 4 years ago tho)

    stock Mazda backbox (only backbox nothing else) to fix blowing exhaust 180 quid

    full custom Power Flow exhaust (CAT back, and still going good 4 years later :) ) 250 quid


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