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Help with building your Speeduino, installing it, getting it to run etc.
By Hillmanjames
#49731
Hello everyone, I'm running a DIY EFI speeduino on the latest firmware on a 1.8 vvt mx5 engine using the stock cam trigger , 36-1 crank trigger and fully sequential fuel/spark.

I did have my Trigger Angle at +315 degrees, but the VVT would not function at all at this setting. I have moved the trigger to +90 degrees and the VVT has started working.

The issue that i have is that when the camshaft advances with an increase in duty as it should, the Cam angle in tuner studio is decreasing into the negative. (cam angle set to zero with zero duty)

I have tried changing the "increase duty direction" from advance to retard. This just sent it to full advance upon startup (still showing a negative value for the cam angle) and it would not try to correct if i gave it throttle to keep it running.

Is this a settings issue on my side or an issue further in the firmware?

I know that my vvt is physically functioning correctly as it was working on the stock mx5 cam and crank triggers. The issues have only arose after the switch to a 36 tooth crank trigger

msq attached, Ill try upload a video too
Attachments
(78.04 KiB) Downloaded 13 times
By Hillmanjames
#49758
I've uploaded Pazi88's firmware (https://github.com/noisymime/speeduino/pull/551) as recommended in the Slack chat, this has help a little, but the vvt was still going backwards.

Again i tried changing the setting from advance to retard etc.

The way i got round it was to set "vvt duty" and "advance at zero duty" to zero and see what the cam angle gauge was reading (-36 degrees)

I then set duty to 95% and measured the cam angle again (-90 degrees)

Taking the -90 from the -36 gave me 54 degrees of cam angle change, I then set my target cam angle table to (54 - (required value))

Set the cam angle at zero duty to -90 and then it all worked :)

Everything is abit arse about tit backwards, but it works and its running nice and accurately!

I wouldnt say the issue is fixed, but it is a way round it

Log and msq attached for some light reading
Attachments
(3.11 MiB) Downloaded 16 times
(78.1 KiB) Downloaded 12 times
By pani
#49762
Both your tunes have fixed timing angle turned on. I really hope you are not operating the engine with these msq's.
By Vauhtivaunu
#49764
Hillmanjames wrote:
Fri Apr 23, 2021 5:07 pm


Everything is abit arse about tit backwards, but it works and its running nice and accurately!
Have you checked that cam does relly what you think? Or are you just reading sensor values?

There is much misconception with VVT systems that people trust only data reding from ECU. Should everyone using VVT somehow to check cam timing like crank base timing. It can be PITA to work, but it is must to do thing if one is going to get VVT work properely.

People here don´t even check crank base timing properely so I´m bit sceptic that cam timing would work even 1% Speeduino users without learning basic things how things work and RTFM.
By pazi88
#49776
For simplicity speeduino vvt implementation just takes current crank angle from the internal calculations as cam angle, everytime cam signal triggers. Then subtracts "cam angle at zero duty" from that and that's it. No extra calculations on top of that (you try to avoid unnecessary calculstions on Mega2560). I have noticed that depending on what ecu you compare, the cam angle can behave reversed in speeduino. But it doesn't prevent from using it and you can set the closed loop vvt settings as you did as for example.

The main change in that PR is that the reversing of VVT PID direction works in such way that it actually works and that the PID gains also work properly. So with those changes the closed loop VVT is lot more usable than it was.
By Hillmanjames
#49849
Vauhtivaunu wrote:
Fri Apr 23, 2021 7:42 pm
Hillmanjames wrote:
Fri Apr 23, 2021 5:07 pm


Everything is abit arse about tit backwards, but it works and its running nice and accurately!
Have you checked that cam does relly what you think? Or are you just reading sensor values?

There is much misconception with VVT systems that people trust only data reding from ECU. Should everyone using VVT somehow to check cam timing like crank base timing. It can be PITA to work, but it is must to do thing if one is going to get VVT work properely.

People here don´t even check crank base timing properely so I´m bit sceptic that cam timing would work even 1% Speeduino users without learning basic things how things work and RTFM.
The only way I've been able to check is comparing trigger logs, the reason I'm saying it's going "backwards" is because it was working "correctly" with the stock 4 tooth crank trigger and it's only gone awry when I've fitted the 36-1 crank trigger.

It is working now, so I'm happy, but this might be useful info for people such as Pazi (many thanks for your work!) who haven't seen anything like this come up in testing
By Hillmanjames
#49850
pani wrote:
Fri Apr 23, 2021 6:54 pm
Both your tunes have fixed timing angle turned on. I really hope you are not operating the engine with these msq's.
No, this was left on just for testing and verifying timing. I'm back on the proper spark map for normal operation.
By pazi88
#49851
Hillmanjames wrote:
Mon Apr 26, 2021 8:57 am

The only way I've been able to check is comparing trigger logs, the reason I'm saying it's going "backwards" is because it was working "correctly" with the stock 4 tooth crank trigger and it's only gone awry when I've fitted the 36-1 crank trigger.

It is working now, so I'm happy, but this might be useful info for people such as Pazi (many thanks for your work!) who haven't seen anything like this come up in testing
ok. It looks like that in Miata trigger the cam angle is 370 - current crank angle. So that explains why it's now reversed with missing tooth trigger. Don't know why that's the calculation for Miata, but guessing that's to match stock ecu or something.
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