Can you enable VVT on DIYPNP like that ?
 

Hey,

As I understand it the VVT solenoid can be enabled and disabled using 12v switch.
If so, can I just do the following ?

Enable vvt above 1700rpm and disable it above 5000rpm, I verifid this range while tuning vvt on a dyno.

https://www.miataturbo.net/attachmen...1&d=1484389640

Try and it and report back your findings.

VVT is PWM so I don't know how it will react to 100% duty cycle and how that might affect application and durability of the solenoid. Also, don't know how much amperage that might consume.

Then is the matter of going from zero retard to full retard so abruptly and how the engine will react to that.

And also since the default is fully retarded, you will have to have it "on" while not in the range you want and then turn it off.

And I would imagine you would want to add a load parameter as otherwise it will go full retard advanced every time you are in the 1700-5000 RPM range. Edit: brain fart, you advance to get mid-range up, not retard.

It's not something I would do as I know that VVT angle is more than just RPM dependent and all or nothing. Buying a VVTuner is something I would do although I believe you are not in the USA and a $200 part is much more expensive wherever you may be.

It will cause atrocious low-load driveability. VVT is not an on-off switch. It requires closed-loop PID control that your ECU does not have.

I tested full retard and full advance on the dyno and I've found out that full advance will get me around 40deg, I run once with all vvt set to 0deg and once with all set to 40deg.

I have found out that between 2500-5000rpm the engine like it at 40deg, all the rest is transition areas and no advance @ low load (areas that almost can not/are not visited, 0-1500rpm)

The vvt is mechanical hydraulic system, even if I command 40deg it would take some time to get there - it is not momentarily.

The intake maps I mapped on the dyno show a full retard under 2500 and above 5000, between it likes full advance.

I'll test it and report back.

I'm building a vvt engine for around 350hp, if I can get away without changing my diypnp - it would be great (and yes I know about the alternator).

Cheers.
Elior

plenty of people on m.net were doing this for years...

This isn't correct, sorry.

Real VVT maps use full advance for a very narrow window. It doesn't "like full advance until 5000rpm" as you have implied here.

What you are doing will work, but it is a bandaid that will cause poor driveability and less power than a proper VVT controller. I really don't understand the logic behind keeping your ECU when a VVTuner or even a complete ECU upgrade would add minimal comparative cost to your build.

When tested is does not react momentarily.

The dyno test showed what the engine like 40deg from 2500-5000 - it will be hard to convince it otherwise...

Even on other applications I tuned vvt on the best results came with full advance and narrow transit, no poor driveability and max power proved on the dyno.

I don't say I will not upgrade I just came to think that may be I can do vvt with my diypnp this way, and we are discussing it, that is all.

It's more correct than not. There is delay between command and when the phaser swings to full (or target). The length of delay is dependent on several factors such as distance to target (target error), oil pressure, oil viscosity, and system voltage.


I'll agree with you that it is less ideal, but treating the BP VVT like a 2-stage system can work. It was done for years. AFAIK, the VVTuner was the first programmable closed loop VVT control on the market for the BP. Before that, anything aftermarket was 2-stage. Many used RPM window switches. I know Hydra was on the market before VVTuner, but it was still an open loop system for a long time.

I think the key to making it work halfway decent would be to use a MAF for fuel load as that should automatically compensate for VVT transition errors, assuming the MAF transfer is correct.

That aside, I would not run 2-stage VVT as hardware for proper closed loop operation is readily available at moderate cost.