GGevo921

iTrader: (24)

I have found degreeing cams to be very important part of any camshaft install and am wondering if there a way to degree the MIVEC Cam Gear? I know we can degree the exhaust side for the 9 with an adjustable cam gear, but with no adjustable MIVEC cam gear (or that i am aware of) I wanted to know if anyone has come across a way to properly degree a MIVEC camshaft.

SloEvo12

iTrader: (8)

I know this is years old, but I figured I'd bump it rather than starting a new thread...

Whenever degreeing an Evo 9s cams with Mivec what should the process be? Should two adjustable cam gears be used, cam degreed, and then Mivec gear installed with the Mivec map "based"/" zeroed" at whatever value was degreed for the intake cam during the process? Any input would be great!

kikiturbo

the inlet cam on the mivec is "degreed" by the ECU... there is a cam sensor and ECU reads the cam position and adjusts the mivec gear accordingly.. everything else is a matter of adjusting the mivec table to your liking..

TrendSetter

iTrader: (1)

that is assuming the lobes are clocked to the alignment pin correctly. if you assume that, why bother degreeing at all?

kikiturbo

you cant "degree" the mivec cam in a normal sense of the word because the cam is not fixed to the cam gear but is floating on oil pressure within the mivec gear. It really doesnt matter how the pin is aligned, but it is important that the cam sensor at the end of the cam is fixed properly.

The only way to degree the mivec cam is to change the values in the mivec table and see the best power/tq curve you can get.

LetsGetThisDone

iTrader: (1)

No, you're relying on the trigger wheel on the other end of the cam being lined up to the lobes correctly. The ECU "degrees" the cam based on the trigger wheel on the cam, and on the crank. It the adjusts the mivec gear accordingly to that the inputs from those sensors to match the advance or retard that you have inputted into the mivec table.

SloEvo12

iTrader: (8)

You're skirting what I'm asking with this response - your first response was a bit more simplistic than my question;

You CAN degree both the intake and exhaust cams on a Mivec head by utilizing two adjustable cam gears and treating them as if they are both fixed cams. My question is whether or not that makes any sense. In my mind, I'm thinking the process to properly degreeing cams with a Mivec head is to utilize two adjustable cam gears, degree the cams per the specs, and then treat whatever the intake cam adjustment is as the "base"/"zero"for your Mivec table. I don't know if that practically makes any sense though. Or are people only trying to degree the exhaust cam and hoping the dyno shows what works for the intake cam (and having their valve to piston clearance specs handy)? That's really where my question is coming from; how are people degreeing their cams? Not at all how are they utilizing their tuning tools to move the intake cam with Mivec.

LetsGetThisDone

iTrader: (1)

Your missing the point that the ECU zeros the cam based the two trigger wheels, not the cam gear. So what you're talking about doing, doesn't help. If anything, if the cam is off (not machined correctly), you're making it worse.

SloEvo12

iTrader: (8)

The ECU will "zero" to whatever value is assigned - which doesn't have to be actual/true 0 in the ECU. If you degree the cams and find that per the cam card you should be at E - 3*A and I - 2*R then why couldn't your Mivec map indicate -2 (maybe some other arbitrary value) whenever you tune the car and then you'd set the adjustable exhaust cam gear to 3*A?

kikiturbo

but why would you follow some number on a cam card when 15 minutes on a dyno and a couple of map changes will give you the answers you want.? The whole point of following cam cards is that you do not have to wench on the cams when you tune.

Even if you degree the cam as per the cam card, you have enough slack and tolerance in the system that the ECU doesnt see a calibrated angle measurement... cam is not connected to a highly sensitive rotational encoder... it is a simple sensor that can be off a couple of degrees anyhow..so any measurement you can make on the cam itself is pretty useless.

LetsGetThisDone

iTrader: (1)

But you're not zeroing the cam with what the ECU uses. If the gear alignment dowel is a bit off, who's to say the trigger wheel is the same amount off?

BiFfMaN

iTrader: (3)

Well here is what i do know from my experience.

With the power off, the Mivec Valve does let oil pass into the Mivec Gear. This fills it up and helps hold it in position.

I filled the whole system using a Drill on the oil pump to prime the system until oil came out of the head. Without the Timing belt installed of course.

Doing the Prescribed Cam Degreeing procedures with solid lifters i got my expected range for my build within a degree.

Despite no oil pressure, the oil in the gear being not compressible , held it relatively in place. I moved it back and forth to be certain. Does it bleed now over time, it might, but during the procedure i just rotated over 3 times then took a reading. This was necessary to keep oil moving.

Now take this as you will, i found nothing helping me also, SO i had to figure it out.

Engine is running now with just a Stock Mivec map, But i will adjust as needed to find out where the motor likes it.

doghouse

iTrader: (11)

Nice

TrendSetter

iTrader: (1)

jesus christ the point of my post is that the index the pcm uses may not be exactly in line with the lobes. ive seen it happen several times. it doesnt ****ing matter which end of the cam you refer to. all the pcm can do from there is relatively adjust, so youre still assuming zero is zero.

LetsGetThisDone

iTrader: (1)

Ok, but your degreeing the cam with the gear, which is aligned to the cam with the dowel. You're not degreeing the cam with the trigger wheel. So, if in order to zero the cam, you need to advance the gear 4* because the dowel is retarded 4*, who is to say that the trigger wheel is off by the same 4*? Say the trigger wheel is only retarded 2*. Now you compensate your MIVEC table with 4* of advance, but since the trigger wheel was only 2* retarded, your cam is now 2* advanced, not zero. Follow?


This is why kiki is say to just spend the extra 30 minutes on the dyno playing with the mivec to find the best power/spool characteristics. Its a lot less time than playing around with solid lifters and redoing the timing belt in an attempt to "degree" the cam.