VVT ideas and testers

[jsmcortina]

The VVT code wants a multi-tooth crank wheel and often a number of teeth on the cam for accurate closed loop positioning of VVT.

Each VVT mode has to be added individually. I'm not aware of any OEM installs using VVT and EDIS so that is not supported.

(However, it is possible to use a cam sensor with EDIS in MS3 for sequential fuel)

James

[adamnreeves]

The VVT code wants a multi-tooth crank wheel and often a number of teeth on the cam for accurate closed loop positioning of VVT.

Each VVT mode has to be added individually. I'm not aware of any OEM installs using VVT and EDIS so that is not supported.

(However, it is possible to use a cam sensor with EDIS in MS3 for sequential fuel)

James

Thanks James. This is for a Ford Duratec engine and I am told that the cam sensor uses a single mark but yes you are right it doesn't normally run EDIS. We will be dispensing with the EDIS sometime this year and driving the coil pack directly. So in the mean time will use PWM-A.

[dfzuntor]

How are you controlling your cam lift change point?
Why do you need two tables?
e.g. if lift change happens at a fixed point then tune for high lift above and low lift below?

James

The lift is controlled by a Generic PWM, in form of TPS VS RPM, so there is a point that I have mid TPS and full load for example. That is the only reason that it will be necesary.
Thanks David

[jsmcortina]

How about changing the gen PWM A to use the same load axis? Then the lift solenoid and VVT will be in sync.

James

[dfzuntor]

How about changing the gen PWM A to use the same load axis? Then the lift solenoid and VVT will be in sync.

James

I'll try it to see if it likes it

Thanks James

David

[sportage4x4]

I've got a question regarding the maserati/ferrari V8 engine. These engines are fitted with VVT on both intake cams. The crank is a 60-2, standard bosch fare. The cam wheels are similar to the VW 4 tooth wheels, but with 3 short and one long tooth. I will be plotting the tooth edges versus crank angle in the coming week, but was just curious as to whether or not this was possible with current code.

[jsmcortina]

Sounds like it should already be supported.

James

[adamnreeves]

I am wanting to use VVT on a Ford Zetec engine.

The Ford Zetec uses VVT on the inlet camshaft only. The standard camshaft trigger wheel has 5 teeth which are read by the VR sensor. These teeth are organised in an 4 + 1 extra pattern so that the position of the camshaft in relation to the crank can be ascertained. Photo below off the camshaft to illustrate the trigger wheel:



Here is a photo of the camshaft installed in the head. You can see the solenoid between the inlet and exhaust camshafts which is used to adjust the camshaft timing:



The crank position is read by another VR sensor which reads directly off the fly wheel which uses a 36 with missing 1 pattern.




The setup is using EDIS-4 for igition via the SAW/PIP interface to Megasquirt. However we are removing this module this weekend and will use Megasquirt to drive the coil pack direcly in a wasted spark configuration.

I have started a new tune for Alpha 18 and also tried the latest Beta 22. Set ignition option to tooth wheel. I have tried semi and fully sequential injection.

Under the developmental VVT settings, cam decoder I only seem to have standard or BMW V10 patterns. I was under the impression they would be several here?
I can configure how many teeth but cannot describe the asymetrical pattern of the OEM camshaft trigger wheel like I can with the crankshaft trigger.



So am I doing something wrong or is the Ford Zetec VVT not yet coded?

[jsmcortina]

Set the main wheel mode to Zetec VCT in ignition settings.

James

[adamnreeves]

Set the main wheel mode to Zetec VCT in ignition settings.

James

Thanks James

[Hiluxfan]

Hi everyone
I am still trying to find out if MS3X will be able to dirve the VVTI on the Lexus 3UZ.
Ive attached some more information.
Thanks in advance.

[jsmcortina]

It won't work as-is due to the uneven cam pattern. A special decoder would need writing.

James

[Hiluxfan]

Thanks a lot for your reply James.
What would be the best way of solving this? The 1uz (VVTI) and 3uz are getting very popular for transplants but the main headache is to get the VVTI working.
This is easily done by using the standard ECU on the older versions (1uz VVTI) but the newer ones has all the security built in and you need everything from the donor car.
I really think the MS3x would be a viable option if we can get the VVTI to work.

[jamies]

james, very similar to the image of the zetec cam above, we have some 6 cylinder DOHC engines here in AUS which use a similar cam pattern, where there are three teeth on the cam at 120 degree spacings and a (+1) fourth tooth inbetween two of the three. Crank wheel is 36-1 Could this pattern also be supported by MS3?

[Hiluxfan]

Ok.
Took the plunge today and ordered the kits from DIYAuto Tune.
From what I have read so far, I am confident the 3uz VVTI can be made to work. With the help of all you clever people of course!
Thanks in advance Guys!

[Hiluxfan]

Wow what great service! Got a call from the post office today. One package waiting to be collected.
Only took a week to ship half way around the earth!

Thanks DIYAuto Tune!!!

[Peter Florance]

What about option of using throttle position as vertical axis?

When we installed and tuned the World Challenge car (Motec M-800 and DBW-4) we were advised to use throttle position as the load axis for VVT to avoid a circular reference. They felt that cam position could change MAP, which then could point you to a different point on the target (Motec uses term "aim") table, possible making the system unstable.

So far the M54 I'm tuning is well behaved, but I'm wondering about a cam with more overlap.

[Peter Florance]

One other peculiarity, both in 17 and 18, is that the duty seems to be backwards for exhaust. For my intake cam duty of 0% means the solenoid is getting no power. On the exhaust cam a reported duty of 100% means the solenoid is getting no power (verified on my oscilloscope) 0% gives me full retard on the exhaust cam.

That's in the nature of the way the code is written. Ken is best to explain.

James

I'm sure it was done to economize on code, to re-use the same PID algorythm, but the result is that the exhaust is very confusing to configure compared to the intake. In test mode, you need to know that it's backwards or you're lost. It's not 0% you need to start with, but 100%

The exhaust table is at least consistent in that cam minimum position + table = target, but it's slightly confusing needing to write the table in terms of advance when you're trying to retard.

So what that means is, if there is a 40 degree control range for exhaust cam, and it uses more duty to retard cam, table entry of 40 degrees is basically "no retard" and 0 would be max retard; relative to minimum position?

Thanks

[Peter Florance]

Something that seems a little problematic for setups that require current to retard exhaust cam from rest: before the engine runs, the amount of current through the output seems quite high. To the point where I might repurpose an LED output to shut off the drive if RPM is 0.

Ideally it would be better if a retarded cam PID loop just worked in the retard direction with retard targets, instead of inverting the output polarity.

Having said that, I have gotten my head around the advance #. So as long as I can fix above with hardware, I'm ok.

[jsmcortina]

What about option of using throttle position as vertical axis?

Done in 1.3

I've asked Ken to consider the exhaust cam query as he is best to explain.

James