rusefi.com

NB2 Miata H72D. Customer reported that VVT response would drop out intermittently. It is captured in the log screenshot below. I am waiting on the tune so that i can upload the full log. Earlier in the log, VVT position seemed to be responding as it needed to. Do we have VVT target available or only duty cycle table?

So we have a usability issue - menu name says "target" but actual table does not specify what it is. Let's make progress here

At the moment rusEFI has ONLY closed-loop VVT control, it's always target never duty cycle.

At the moment I have no idea what's going on with the whole drop

tune https://rusefi.com/online/view.php?msq=696
Complete Log https://rusefi.com/online/view.php?log=391

We do not log VVT target by default

We have "debug mode" setting which gives half a dozen of VVT entry points but it has to be enabled explicitly.

See bottom of

Progress: min/max tooltips

unfinished progress: button to enable VVT PID debug mode

Output Max Duty Cycle?

BeerMoneyMotorsports wrote: ↑

Thu Oct 28, 2021 6:04 pm

Output Max Duty Cycle?

I like it, done!

input from Tuner- "after adjusting PIDs, it seemed to resolved the issue".

I will poke the owner for updates.

Hello! I am the owner in question dealing with a potential vvt issue.


The vvt seems to want to work intermittently

I will include the most recent datalog hopefully showcasing the issue and the current tune the car is running

Im think that the vvt actuator may be bad as I also swapped the vvt solenoid to no effect. The car does run better with the vvt unplugged





Tune: https://rusefi.com/online/view.php?msq=700

Datalog: https://rusefi.com/online/view.php?log=394

Can you set debug mode to "VVT1 PID" and take another log? That will give additional information about what's going on.

Alright, I'll take another log with the debug mode set to that. I'll upload it once I get around to it!

Got the new datalog with "vvt1 pid" debug selected
The vvt would still work intermittently and would sometimes fully advance to 44-45 degrees causing the car to run terribly


Datalog:https://rusefi.com/online/view.php?log=395

Your hardware is fine. PID settings are pretty clearly super wrong.

Where did you get your VVT PID settings? Looking at the output duty cycle, your settings are not nearly strong enough. The controller is responding to input, but extremely slowly, so you end up with relatively random solenoid duty.

Your min/max on the VVT PID should also be further apart - try min/max of 10/70, and MUCH higher gains. Start with just some P to see what happens.

mck1117 wrote: ↑

Tue Nov 02, 2021 5:34 pm

Your hardware is fine. PID settings are pretty clearly super wrong.

Where did you get your VVT PID settings? Looking at the output duty cycle, your settings are not nearly strong enough. The controller is responding to input, but extremely slowly, so you end up with relatively random solenoid duty.

Your min/max on the VVT PID should also be further apart - try min/max of 10/70, and MUCH higher gains. Start with just some P to see what happens.

https://www.facebook.com/stevesremotetuning was tuning the car.

Ill give that a shot and monitor how the vvt reacts.

Nightsknight45 wrote: ↑

Tue Nov 02, 2021 5:49 pm

https://www.facebook.com/stevesremotetuning was tuning the car.

With all due respect, this means your tuner didn't actually look at VVT at all, and likely didn't actually tune your car.

I was able to get the vvt to respond pretty accurately under these settings however the car has a very jerky takeoff from stops

Any input on what to change/where I should be looking to fix that? (car takes off from stops fine with vvt unplugged)


Latest Datalog: https://rusefi.com/online/view.php?log=397

mck1117 wrote: ↑

Tue Nov 02, 2021 5:53 pm

Nightsknight45 wrote: ↑

Tue Nov 02, 2021 5:49 pm

https://www.facebook.com/stevesremotetuning was tuning the car.

With all due respect, this means your tuner didn't actually look at VVT at all, and likely didn't actually tune your car.

No worries man, to be honest, you are probably right... it was sort of a waste of money for what I got.

Nightsknight45 wrote: ↑

Tue Nov 02, 2021 11:10 pm

I was able to get the vvt to respond pretty accurately under these settings...

Awesome - this log looks MUCH better with respect to VVT control!

Nightsknight45 wrote: ↑

Tue Nov 02, 2021 11:10 pm

...however the car has a very jerky takeoff from stops

Any input on what to change/where I should be looking to fix that? (car takes off from stops fine with vvt unplugged)

it looks like your cam target table is pretty aggressive in here:
The VVT target on an intake-VVT-only engine (like the NB2) is your overlap control: more cam angle = more overlap. Right now, your tune is trying to bonk in a bunch of overlap the instant you touch the accelerator, which is probably what you're feeling. Pull out that timing in the "off idle" regime, and see what happens.

Something like this might be worth a shot:

This is what i had on my old VVT car with MS.

BeerMoneyMotorsports wrote: ↑

Tue Nov 02, 2021 11:28 pm

This is what i had on my old VVT car with MS.

Did that use TPS or MAP for the Y axis?

mck1117 wrote: ↑

Tue Nov 02, 2021 11:26 pm

Something like this might be worth a shot:

image.png

Alright! I will give this a try and get another Datalog sometime tomorrow! I really appreciate the help!!

rpm and load