I don't think it matters either. I also have never heard about the oil being too cold for Mivec

 

Yeah, I think it was that the oil couldnt build up enough pressure to activate MIVEC, due in part (or mostly) to its cold temperature. I think it happened to Diavlo (correct me if I´m wrong since I searched and didnt exactly found what I was looking for) after he did his engine swap.

 

his was an oil cooler problem. oil would have more viscosity (and therefore more pressure) at lower temperatures. really there is no instance that you won't be able to build up enough oil pressure, only 45psi is required, unless you just plain don't have enough oil in the pan.

 

I guess then that I misinterpreted his problem if it was due to a clogged cooler or any other problem of the sort.

Sorry for this being a little OT:
I understand that there should be no instance where the engine (even with the cooler) cannot build enough pressure, but what I dont understand is how can it have more pressure when being cold due to viscosity? Could you further explain?
What I've always been taught (and thats where I based my opinion on) is that in any fluid, Pressure and Volume depend directly on Temperature and vice-versa (PV=nRT, R=const. and not taking "n" into consideration), so if the temperature goes down, so will either pressure or volume or both, regardless of viscosity.

 

the pressure, and it's limits, are created by the pump in the engine. while T is in the equation the pump creates the pressure. that equation would have much more affect on a gas than a liquid, especially in a pumping situation.

I was referring to the viscosity of the oil. the colder the thicker, the hotter the thinner; which would pretty much reverse (and I am obviously generalizing a whole lot here) the effects of the temperature change.

does that help, or do you have a different opinion we can discuss further? I love it when threads turn into tech discussions

also, it was not a clogged oil cooler. the oil pump could not provide enough pressure with the added volume in the system to activate the mivec system. I think this could be in part because the oil cooler assembly was above the oil pan, and it's volume could not be added to the engine oil capacity. I am not sure it would make a difference, as there is also added resistance to flow in an oil cooler, but it's the only way I could think to try and use one after I heard his problem. not real important unless you are turbo anyway

 

Well, if you wanna turn it into a tech discussion, then its fine by me (but you'll have to wait a bit for me to read and research a little more about it ).

I know about the viscosity and how it works; for instance, it will be harder to move a block through cold oil than through that same oil when hot.

So lets see if I get it straight now...If its cold, it would have more resistance to flow in the engine, thus reducing pressure (measuring it at the highest point where it flows (since the oil just doesnt want to go up there)), EXCEPT RIGHT AT THE PUMP, since the pump will be working a bit harder to move the oil through the passages. With that given, I think the pressure should be higher right after the pump (so if the sensor is put there, MIVEC will always activate). Now, given that same situation, if we put the sensor just upstream of the pump, then, due to the resistance of the cold oil to flow up and through the engine, the pressure will be lower and may not be enough to activate MIVEC while its still cold (unless the pressure drop is insignificant).

Did I get it right???