VVT setup and test procedure - help please
 

Hi,

as I got my VVT swapped 96 Euro-MX-5 up and running I want to make sure now, that I get the best out of the VVT.

I found various threads on the VVT subject with various very different VVT tables. Also I did found that it is important to set up the dutys and angles correctly - but I found nothing on how to do that.

My logs when driving yesterday show a maximum VVT angle of 40° (target was higher but the actual VVT angle always stopped at 40°)

Can someone please give my a nice (and VVT noob friendly) "How to set your VVT up correcty for the first time" ?

I would really appreciate your help!
Thanks!

Nobody done this before?

Funny because I am looking for the exact same thing. If I find something I will pass it your way, I would appreciate the same.

I assume that you have found (and read) https://www.miataturbo.net/megasquir...-tuning-64590/

That is where I think I will gain the best info, folks like Emilio, Rev, Matt, Y8s and other people vastly more versed on this than I ever will be are all over the topic.

Of course I have seen this thread - but I haven't found out how to test/evaluate the base settings:

I read that CAM minimum and maximum are important...

-- Cam Settings --
CAM1
Input: Main cam
Output: Nitrous2
Minimum: 275.0
Maximum: 319.0
-How do I find this settings?
int.exh.: Intake

Dutys:
I had a look at a log I took with the car, my Minimum VVT duty was 22% and the VVT is reaching the maximum angle at a duty of ~80% - so should I use these as the minimum and maximum dutys?

like
Minimum VVT duty (%) 20
Maximum VVT duty (%) 85

or something like this? I guess that would make it easier for the PID to follow the target - though I am quite happy how close to the target it is...

I would really appreciate some input on that... Thanks!

If I remember correctly, this is how I got my min and max angles.
Go into test mode under the vvt settings tab. Set duty cycle to 0 while engine is at idle. Note cam angle under the gauge cluster. This is your min. Now, rev the engine to 3000 so it doesn't stall out and set duty cycle to max. Note cam angle, this is your max. I ended up with 277.3 min and 323.3 for max. I confirmed this by setting vvt advance to 0 in the vvt map and sure enough, vvt angle held a solid 0 at idle. Reved engine to a set rpm, and the vvt angle matched exactly what was set in the vvt map. If this is incorrect, I'd love to hear the correct method, but so far this has gotten me perfect vvt cam angles.
If it matters for you, PID settings are 50,8,80.

O.K. I checked this out yesterday - the test showed a min. of 0 deg. and a max of ~39 deg. VVT angle.

But what about the Minimum and Maximum abs. deg. - how do I find these out? It's at 275 and 315 now for me - (which equals 40° range)

You use test mode and force the VVT duty cycle to 0 to find the minimum absolute angle (create a gauge on your Tunerstudio dash to see/read VVT angle). Then using test mode increase duty cycle until the cam stops advancing, which will provide both your max VVT angle (gauge on Tunerstudio dashboard) and max VVT duty cycle %. If you decrease the duty cycle back to zero and slowly increase the %, while observing the actual VVT angle gauge, the minimum duty cycle should be the % when the VVT angle just starts to increase.

Note that you should try setting the minimum duty cycle just under the actual % when the VVT angle starts to move. VVT operation changes with oil team/pressure/viscosity, so this way you help ensure that the MS will actually be able to leave the VVT angle at the fully retarded position. I am going to try this with my MS3, as sometimes I get some bouncing of the actual VVT angle around the minimum by a few degrees, even with no advance at that point in the VVT angle map. Try it for yourself and see if it makes a difference.

I have to revive this old thread- a friend of mine has done a VVT swap into a 1991 and the car is running pretty solid. Only a VVT1 err is popping up everytime the car is running and the VVT isn't operating.

So I had a look at the VVT setup procedure and can't really remember how I can find the "abs deg." min value.

I tested on my car with the 1.5.1 firmware.

Set the VVT in testmode -

0% duty - VVT angle is 0 and car is idling.
stepping up the duty and at around 35% duty the car is starting to stumble and VVT angle is climbing up to 44%
stepping up the duty to 100% - need to keep the car running with a lot of throttle - VVT angle stays at 44% no change to VVT angle no matter what duty from 35 to 100%

I guess those 44% shows the max. VVT angle which equals the 270-314 range that is in the abs. deg. settings.

But how did I set the test mode to find the ags. deg. min- for the life of it, I can't remember anymore...

Thanks again for your help!

You need to make a gauge on your tuner studio dash board that can show you the absolute VVT angle. The gauge coupled with the test mode is how you find the correct vvt angle.

I already made 3 gauges- VVT duty, VVT angle, VVT target. The angle gauge only shows the relative values- which gauge will show the absolute values?

VVT Duty is a % number based on utilization. I think it goes from 0 to 100% and theoretically, 0 would be no vvt advance and 100 is max advance. I did not change the duty % from the base tune. VVT angle is based in degrees. 0 to 360. VVT Target is in degrees and looks at the vvt table that you make to command the vvt. I think the vvt effectively caps out somewhere around 42 ish degrees advanced. So the table you make would be valued from 0 to 42 or thereabouts.

On my car specifically, I think my min value was around 272.5 or thereabouts. Max commanded value ended up around 314.5 ish. There is a spread of 40 degrees there. So on your VVT table you know you can command any number between 0 degrees advanced and 42 degrees advanced based off of your min and max values.

Here is my TLDR on researching and setting up VVT:

1. The way to derive the min and max values is to start the car and hold it at a constant 3k rpm or so.
2. Then while you have your gauges available start to manually increase the duty cycle of the vvt solenoid.
3. At 0 duty cycle for VVT log what the VVT Angle is.
4. This would be your 0 degrees advanced value.
5. Then slowly add vvt duty cycle to advance the VVT. I say slowly, just don't go from 0 to 100 because the engine will try to bog down.
6. Once you are at 100% duty cycle on the VVT see what the current vvt angle is. That will be your max value. You might not need to get to 100%, just keep increasing the vvt duty cycle until the VVT angle stops increasing. Wherever it maxes out is your max angle.
7. Go to your vvt settings and change the min and max values to the values your derived. What was your min value with 0 duty cycle added and what was your max value with 100% duty cycle added.
8. Subtract your max value from your min value and that is the range that you can use for your VVT table.

These values should get you close but you will need to do the final testing on your end to find what is specific to your use case.
I am not holding my vvt table as being the end all be all correct answer. I made some informed decisions with tuning and did some back to back tests and then ran out of time. I am sure there is still optimization to be had.


https://cimg9.ibsrv.net/gimg/www.mia...2082dd2ab8.png
https://cimg0.ibsrv.net/gimg/www.mia...f0cc47a461.png

Set min and max angles to 0
create a gauge for vvt angle
Using test mode, run motor with hot oil at 3krpm and VVT duty 0, this is your baseline min
do same with VVT duty at 100, this is your baseline max
Enter 0.5 degrees less than the gauge number for the min
Enter 1 degree higher for the max

Ok, I think I found my mistake - I need to set the VVT min and max angles to 0 first and then do the test procedure! My friend already had some values in tghere, so the angle gauge only reads the relative values.

Thanks to you guys we got the main setup done- surprisingly the min and max abs. angles are at 249 and 294 deg. This seems odd to me- could his intake cam be wrong by one tooth?

Apart from that the VVT is working flawless now.

Out of curiosity is your ignition set to rising edge or falling edge? Have you tried flipping whatever setting you have and trying again? I think I had an issue with that once but I don't know if it was an actual issue or a bug with the software.

It's not on my car, but on a friends car- we have the same setup (36/2 wheel) and settings though in this aspect- so there shouldn't be the 20deg difference in my opinion