VVT ideas and testers

[jsmcortina]

In some future MS3 code we plan on adding VVT support (this will most likely be the 1.1 series of alpha codes.)

As this is new ground, we will be looking for some willing testers to try this out and help fine-tune the feature.

Requirements of testers
- already have MS3 and have a good running tune
- have an engine with VVT on it
- are using stock sensors / trigger wheels
- have time and patience

Pretty much each engine implements VVT differently and will likely require specific modifications to the wheel decoders.

So if you could be a serious tester, please post up with what you have and what wheel mode you are using now and any technical data you can find about VVT control on your engine.

James

[y8s]

Have a well running 2001 mazda miata with turbo and I'm already doing open loop VVT with a 78Hz PWM output and it works very nicely.

running stock 2001 mazda crank and cam sensors.

Technical data pasted from this thread at miataturbo.net:
http://www.miataturbo.net/showthread.php?t=27030

I first observed the current waveform on the VVT solenoid as applied by the factory ECU, and cam and crank signals. I could only do it with the car in the garage. When the cam is retarded (idle), there is zero current. When I rev it, it applies ~0.5A. The frequency is around 500 Hz and the duty cycle ranges from from around 40 to 65%. The current ripple is around 20%.

It seems that the solenoid is controlled by current, and its position responds to average current (average over the duty cycle).

The factory ECU will occasionally "blip" the current to 1A (briefly, as in for less than 1 engine cycle (2 revolutions) - perhaps a 'D' term (D in PID). As idle settles down, it will also blip the current briefly - like it wants to advance the cam for a very short time as the idle settles.

So I observed the cam vs crank waveforms as I applied current to the VVT solenoid.

It appears that the control range of current is 0.4 to 0.6A. However there isn't a simple 1 to 1 correspondence between current and advance.

Firstly there is hysteresis. I need to raise current to nearly 0.6A for it to begin advancing, and I have to reduce it nearly 0.4A to begin retarding.

And, once it begins advancing at a given current, it appears to continue advancing until I back the current off. It happens too fast for me to catch with the knob on my power supply.

Someone posted a diagram of the guts of the VVT actuator and the solenoid. I couldn't find it. Maybe by analyzing it, it can shed some light on the behaviour I've observed.

At 0.5-0.52A the valve is in the "hold" position. Below that it retards and keeps retarding, and above that it advances and keeps advancing. Valve sticks a bit thus the hysteresis.

There is a spring loaded stopper pin (lock pin?) that holds the cam in place until there is sufficient oil pressure to move the pin out of the way.

Mechanically, the advance is done in the cam gear. There are two chambers and as each one fills, it either retards or advances the cam.

A spool valve feeds the two chambers. at rest, the solenoid in the spool valve permits flow to the "retard" chamber (advance chamber drains to oil pan) and the cam rests at full retard. when the solenoid is energized, it permits oil flow to the advance chamber (retard oil flows to oil pan). When the spool valve is held half way (.5-.52A--mentioned above), it blocks both passages to the chambers and the cam is held in place.

My map is attached for reference to see how my open loop is set up.

[Paul_VR6]

James,

What's the timeline on this? I have to pull my motor soon to refesh for next season but I might be able to get something done before I do so, depending on timing.

VW 3.2L VR6
Intake cam vvt - 52deg sweep
Exhuast cam vvt - 11deg sweep
60-2 crank trigger
4pulse/rev odd cam trigger on each cam

Currently running it in waste spark/semi seq due to my cam wheel not being supported yet.

I have had good luck just on/off controlling them as both are mainly used for emissions.

In stock form they're both closed loop control using the actual cam angle and varying the duty cycle to the cam solenoids. Looking at the factory ecu when in controlled mode the duty cycle is pretty close to 50% most of the time so the amount of adjustment with the valve must be fairly small once the cam has moved into position.

Let me know what you might need and I'll get it asap. I'm putting one of these in another car over the winter on ms3/3x as well and can use that as a test bed after my car is taken down.

Anyway, keep me posted. This will be a nice next step for MS3.

[prof315]

James,

What's the timeline on this? I have to pull my motor soon to refesh for next season but I might be able to get something done before I do so, depending on timing.

VW 3.2L VR6
Intake cam vvt - 52deg sweep
Exhuast cam vvt - 11deg sweep
60-2 crank trigger
4pulse/rev odd cam trigger on each cam

Currently running it in waste spark/semi seq due to my cam wheel not being supported yet.

I have had good luck just on/off controlling them as both are mainly used for emissions.

In stock form they're both closed loop control using the actual cam angle and varying the duty cycle to the cam solenoids. Looking at the factory ecu when in controlled mode the duty cycle is pretty close to 50% most of the time so the amount of adjustment with the valve must be fairly small once the cam has moved into position.

Let me know what you might need and I'll get it asap. I'm putting one of these in another car over the winter on ms3/3x as well and can use that as a test bed after my car is taken down.

Anyway, keep me posted. This will be a nice next step for MS3.

Just as a note the 4 pulse cam trigger that VW uses is quite common. I have seen it on a couple of Mitsu motors, late model GM Ecotecs, all VWs built in the 2000's and some others. Basically it is 2 wide teeth, then 2 narrow teeth and one edge ( i don't remember if it's the rising or falling edge) of each tooth is 90deg from the same edge on the next tooth. I have the same trigger set up on my 20V head,I just cut all but one of the narrow teeth off so I could go full sequential. My VVT is also made for emissions and is currently being controlled on/off but it only moves the intake cam (22 deg)

[Peter Florance]

Vanos count here?

[Fii]

I would like to sign up for testing.

My setup is Toyota 1zz-fe engine (also applies to 2zz-ge), running in semi-sequential mode with stock sensors. MS3 is not yet installed, I am currently bench testing and working on wiring, but I hope to get it up and running in next month or so. First I am planning to run it parallel to stock ECU and log what is going on.

It has VVTi on intake cam only and is controlled by PWM solenoid.
36-2 crank trigger
3 tooth cam trigger (don't have TunerStudio logs with specifics yet).

Currently I am targeting semi-sequential using just crank wheel, with VVT in on/off mode, because multiple tooth cam wheels are not yet supported.

[prof315]

Vanos count here?

Why not? It changes cam timing. Of course it comes in 2 flavors.....the early version (M50 series motors) which is on/off on the intake cam only and the newer full time PWM version that is on both cams. I have a friend who races BMWs and has done some testing/tuning on the newer version and says that BIG average power and torque gains can be found by playing with dual Vanos.

[Peter Florance]

Vanos count here?

Why not? It changes cam timing. Of course it comes in 2 flavors.....the early version (M50 series motors) which is on/off on the intake cam only and the newer full time PWM version that is on both cams. I have a friend who races BMWs and has done some testing/tuning on the newer version and says that BIG average power and torque gains can be found by playing with dual Vanos.

I've done single Vanos (my first MS2Extra installation with V1.02 firmware) but have a local victim waiting for code for variable version (M54 motor)...

[jsmcortina]

For any of the uneven cam wheels we need a timing diagram and ideally a "log crank and cam" composite log from TunerStudio.

James

[prof315]

Ok I should be able to do that. Would pictures with some notes about the timing help?

[muythaibxr]

For 1.1 we are planning single cam VVT. In 2.0 we'll add support for up to four cams.

Ken

[y8s]

For any of the uneven cam wheels we need a timing diagram and ideally a "log crank and cam" composite log from TunerStudio.

James

are you set for the 99-00 miata?

I probably have the raw logs from the image below somewhere.

[prof315]

Ok some preliminary info on VW 4 pulse cam sensors. I got this measuring the tooth width/gap on a 1.8T 20V cam sensor with a degree wheel but I'm _sure_ that all VWs using this wheel will have the same values. I know the crank wheels are all the same.

Crank Wheel 60-2: missing teeth 78 deg BTC.

Cam wheel 4 teeth, 2 narrow, 2 wide Measurements are in degrees of CAMSHAFT rotation starting at TDC #1 cylinder on the compression stroke.

TDC rising edge narrow tooth
15* ATC falling edge narrow tooth
45* ATC rising edge wide tooth
105* ATC falling edge wide tooth
135* ATC rising edge wide tooth
195* ATC falling edge wide tooth
270* ATC rising edge narrow tooth
285* ATC falling edge narrow tooth

It 's going to take me a bit to get a cam/crank log as I will have to take my motor partially apart to swap cam wheels.
I can also provide pictures of the wheel if needed.

Jeff

[gurov]

for QR25,



the cam signal will shift to the left with relation to the crank, first tooth of the cam signal train would be the reference point.

i'd have to swap the head on my motor to be able to test this as i disabled it in hardware, but i plan on having a test motor set up on a stand to mess with this.

[Paul_VR6]

Good info Jeff! I'll do cam/crank logs of my 6cyl with the vvt on and off to see what the story is there. I do know that the 3.6L V6 has a different trigger arrangement for some reason.

[prof315]

Good info Jeff! I'll do cam/crank logs of my 6cyl with the vvt on and off to see what the story is there. I do know that the 3.6L V6 has a different trigger arrangement for some reason.

Basically what _should _ happen is that pattern of the cam signals will remain constant, but their relation to TDC compression will change as the cam advances and or retards. I should note that the degree values I posted are what would be seen WITHOUT VVT engaged. (I have a spare head that I measured on the bench)

[Ballistic]

Maybe I'd be a better candidate for round two of testing, but let me know if otherwise.

Requirements of testers
- already have MS3 and have a good running tune

A causality dilemma prevents the implementation of MS3 without VVT control, so no I don't have an MS3 on this vehicle with a good running tune.

- have an engine with VVT on it

Yes. I have an '06 Evo. This engine has the standard Mitsubishi wheels on the crank and exhaust cam, and a third wheel on the variable intake cam.

- are using stock sensors / trigger wheels

Yes.

- have time and patience

Yes.

[ca434sbc4]

James

I'll be able to test come later in the year, 12" of snow & -20* C tends to put a damper on testing..

GM 7 notch

PWM VVT sol spring return actuator

I have the full timing diagram documentation for both the cam and crank wheels and can supply.

Thanks

[jsmcortina]

I might have something to test soonish - for data collection only (no control) for "dual+missing" with a single cam tooth and Miata 99-00 modes only.

However, before I post any alpha test code I want RC7 fully tested in the field so we can get 1.0 released.

James

[jsmcortina]

Pre 1.1 alpha 1 now posted with experimental VVT position measuring.

James