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Discussion Starter · #1 ·
mx6 folk--

recently bought a very nice '96 mx-6 m-edition, almost perfect (see my other post about brake drag), one thing i'm curious about on this vehicle is that there is a very appreciable increase in power once the engine gets up above 4500 rpm, the car really seems to want to spend time between 4500 and 6500 rpm, anybody out there able to explain why these engines are so much more potent in that range? mind you, i'm not complaining, i actually LOVE the experience when this thing gets going, just curious to learn more about this car is all, since it's obviously a keeper.

thanks for any insight you can offer!

--josh (buffalo creek, co)
 

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that is the area between peak torque and horsepower. That is why. the expression "coming onto the cam" is exactly what you are feeling.

It's a 4 cyl correct? Mine is the same way. I love the sound of the intake above 4500, really growls
 

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It's the VTEC yo!



haha no in all seriousness it is probably your VRIS.
 

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A sudden surge of torque at 4,250rpm is a common symptom of a bad VRIS#1 (stuck closed), which is most commonly caused by VRIS#1 solenoid being bad. (It feels like a surge of torque because torque is lower than it should be below 4,250rpm.)

If you search here on "4250" you will see numerous posts on how to diagnose and fix this common problem.
 

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That's a mini, not a honda. :rolleyes:
I didn't care what kind of car it was, but more the faked expression on the guys face.

or this one with the rabbits
 

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Discussion Starter · #8 ·
follow-up: reason for power increase above 4500 rpm...

mx6 folk--

yep, sounds like it must be the VRIS, the RPMs where i'm feeling the increase in power correspond precisely to those trigger points. what a cool experience, so palpable, i'm pretty sure the system is working just as it should.

shane333, thanks for the direct link to the VRIS information, very useful, much appreciated!

man, the one problem i'm having with this car is figuring out how to drive it legally, it just constantly wants to get up and run!

--josh
 

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i doubt its the VRIS causing a surge of power, if they are working properly you shouldnt feel a "kick". they are used to make the power band more linear if anything. it may also be that its not more "potent" in that rpm but its just weaker in the lower rpm. i would check for codes and reset the ECU personally, you may end up gaining some low end power if something was wrong.
 

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^Agreed, a properly working VRIS won't cause those symptoms. But a bad VRIS#1 (and good VRIS#2) will cause those symptoms.

To test, observe VRIS#1 actuator (passenger side) with the engine off. (It's on the IM, next to the firewall, has a rubber hose going into a metal cone at one end, and a short metal rod coming out the other end.) With the engine off, it is now in the 'closed' position. Now start the engine, and let it idle. At idle, the VRIS#1 actuator should now be open (metal rod sucked in). I bet yours remains closed.

Next, observe the two VRIS solenoids, side by side on the IM, with wires going in the top, two hoses coming out the bottom, and a little Mitsubishi symbol on top too. Disconnect the wire from solenoid #1 (passenger side), and plug it into solenoid #2 (driver's side). You should now see VRIS#2 actuator open at idle.

So, if VRIS#1 actuator is closed at idle, and VRIS#2 actuator is open at idle when you swap the wires, you can be 99% certain that VRIS#1 solenoid is bad, and should be replaced (junkyard or Mazda dealer).
 

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yes you need to fix your VRIS soon before you fall any further into the Hondaboy mentality.
 

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^Agreed, a properly working VRIS won't cause those symptoms. But a bad VRIS#1 (and good VRIS#2) will cause those symptoms.

To test, observe VRIS#1 actuator (passenger side) with the engine off. (It's on the IM, next to the firewall, has a rubber hose going into a metal cone at one end, and a short metal rod coming out the other end.) With the engine off, it is now in the 'closed' position. Now start the engine, and let it idle. At idle, the VRIS#1 actuator should now be open (metal rod sucked in). I bet yours remains closed.

Next, observe the two VRIS solenoids, side by side on the IM, with wires going in the top, two hoses coming out the bottom, and a little Mitsubishi symbol on top too. Disconnect the wire from solenoid #1 (passenger side), and plug it into solenoid #2 (driver's side). You should now see VRIS#2 actuator open at idle.

So, if VRIS#1 actuator is closed at idle, and VRIS#2 actuator is open at idle when you swap the wires, you can be 99% certain that VRIS#1 solenoid is bad, and should be replaced (junkyard or Mazda dealer).
X2. Try the paper test too.

http://www.mx6.com/forums/2g-mx6-general/204493-age-old-problem-vris-need-some-help-please.html

Here's a good picture of where the VRIS actuators are on the DE manifold.

 

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Discussion Starter · #13 ·
follow-up: reason for power increase above 4500 rpm?

mx6 folk--

just wanted to clarify, i actually don't think there's any sort of problem with what's happening between 4250 and 6500 rpm, i was mostly just trying to get my head around the noticeable increase in power the vehicle has in this range, i'm not getting any sort of surge of torque or anything that's abrupt, it's more like the car just really finds its stride when the VRIS is active, much more responsive acceleration in this range than below, but definitely nothing abrupt or surge-like around 4250, just clearly a different sort of performance above that rpm.

NickR and ChefspOt, good info on the VRIS system, i'm excited to be learning more about this!

--josh
 

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