VVT ideas and testers
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Re: VVT ideas and testers
Ah... the problem was PT6 rather than VVT4. I believe I've found the problem and fixed it.
I'll email some test code shortly.
James
I'll email some test code shortly.
James
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Re: VVT ideas and testers
would it be possible to have a VVT setting for cranking? I was digging through docs on the S54, BMW is setting the cam timing specifically for easier starting. As it is now, I don't see a way to do that with MS3.
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Re: VVT ideas and testers
Sure it'd be possible, but I'm not 100% sure that there's enough oil pressure to actually make the cam move very fast at crank. It seems to me that by the time the cam is in position, the engine would be started already.
Ken
Ken
Megasquirt is not for use on pollution controlled vehicles. Any advice I give is for off road use only.
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Re: VVT ideas and testers
Maybe. The vanos unit might hold enough pressure after shut down, or perhaps they're moving to the cranking position another way. Are all vvt systems oil pressure based?
They're doing it somehow, in any case.
They're doing it somehow, in any case.
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Re: VVT ideas and testers
To my knowledge yes.hassmaschine wrote: Are all vvt systems oil pressure based?
Maybe these engines have great oil pumps? Certainly my Rover V8 (which is known for having poor oil pump) starts before there's any real oil pressure.
James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk
My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
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Re: VVT ideas and testers
hassmaschine wrote:Maybe. The vanos unit might hold enough pressure after shut down, or perhaps they're moving to the cranking position another way. Are all vvt systems oil pressure based?
They're doing it somehow, in any case.
For sure VANOS uses oil pressure as do all of the VVT systems I have worked on (bmw, toyota, honda, nissan, VW, GM, hyundai/kia off the top of my head )
Are you sure that the no oil pressure/rest position isn't just optimised for starting? That's how I would do it but of course I'm not a german engineer .
Linfert Performance/321 Motorsports
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SCCA 2019 SM National Champion Crew Chief
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100s of MS systems built installed and tuned
Support the developers!
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Re: VVT ideas and testers
I think is necessary activate vvt controll few second after start because the oil press is low and when I start the engine I listen a metal noise. If I disable vvt system the noise there is not....
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Re: VVT ideas and testers
Regarding cam position at crank, they are in their starting position without oil pressure. It takes oil pressure to advance the intake/retard the exhaust.
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Re: VVT ideas and testers
I don't know. The S54 is still a bit of a black box to most people. But, that would make sense.prof315 wrote:Are you sure that the no oil pressure/rest position isn't just optimised for starting? That's how I would do it but of course I'm not a german engineer .
so no oil pressure = cranking position. The doc I read just made it sound like they were physically moving the cams to cranking position.hoveringuy wrote:Regarding cam position at crank, they are in their starting position without oil pressure. It takes oil pressure to advance the intake/retard the exhaust.
I think the idea of a delay for VVT is a good idea, until the engine builds up pressure. nobody likes rattly engine noises at 5am..
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Re: VVT ideas and testers
I now have dual-variable VANOS running on my Megaquirt3! (sortoff...) It's actually running on my VANOS controller but the motor is running MS3...hassmaschine wrote:I think the idea of a delay for VVT is a good idea, until the engine builds up pressure. nobody likes rattly engine noises at 5am..
Anyway, temperature regulates the VANOS deployment. I implemented it with a signal from Nitrous 1 that's active when (CLT>100F) and (fuel load>40) This is similar to the VANOS signal on the M50-series engine that were simply on-off. Motor wouldn't run worth a dime if intake was advanced at low temps.
On a warm start you wouldn't nail the throttle before oil pressure built-up, anyway.
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Re: VVT ideas and testers
the idea of a delay for VVT is a very very good idea....
Other Idea:
Is possible calibrate the neutre duty for a single solenoid? I have the differents from left and right.
Other Idea:
Is possible calibrate the neutre duty for a single solenoid? I have the differents from left and right.
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Re: VVT ideas and testers
Hi,
James I have tested your code. Is ok. Chanel 4 work.
Thanks
James I have tested your code. Is ok. Chanel 4 work.
Thanks
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Re: VVT ideas and testers
I made the jump from my dedicated VANOS controller to Megasquirt control of my intake cam yesterday. (BMW M54 engine, Alpha 11 code). Works fine so far, need to reduce frequnency from 99Hz and I found that Hold Duty is ineffective. Hold Duty for me is about 72% which is quite a bit higher than what it is on my dedicated circuit.
Anyone have a "known good" PID for this?
Anyone have a "known good" PID for this?
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Re: VVT ideas and testers
Why not use the current code?
James
James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk
My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
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My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
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Re: VVT ideas and testers
Baby steps. Want to make sure Alpha 11 works ok before I jump to the current Alpha. I'm looking forward to CRC new serial, but what else is different in VVT besides 2JZ support?jsmcortina wrote:Why not use the current code?
James
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Re: VVT ideas and testers
In converting from my standalone VVT controller to Megasquirt, I noticed that the duty cycle required to hold position is significantly higher. Since this should be a mechanical constant of the solenoid I looked a little closer. My standalone controller drives the solenoid through a MOSFET and a Schottky flyback diode tied to +12volts, the signal is clean. The megasquirt signal confirms the 72% duty cycle but also shows a signifcant amount of noise when the MOSFET is open and also voltage near 40volts (I'm using a 10x probe)
My controller runs at 225Hz, I had Megasquirt at 75Hz. Also tried other frequencies but it didn't change anything.
What's going on here?
My controller runs at 225Hz, I had Megasquirt at 75Hz. Also tried other frequencies but it didn't change anything.
What's going on here?
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Re: VVT ideas and testers
Have you installed the diode to S12 as discussed in this topic (or perhaps another VVT one) ?
James
James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk
My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
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My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
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Re: VVT ideas and testers
On my list for tonight. What is the current state-of-the-art.... run an additional diode to S12 or just tie D1c to S12?jsmcortina wrote:Have you installed the diode to S12 as discussed in this topic (or perhaps another VVT one) ?
James
I will post a pic of the new scope trace, of course.
Re: VVT ideas and testers
no diode necessary, just connect the cathode of one of the expander flyback circuit diodes to S12.
Right side of the D1, D2, D3, D4 in the top of the picture below. You'll know it is right because of the continuity between all of those cathodes (and you can see the traces).
Matt
and reference:
Right side of the D1, D2, D3, D4 in the top of the picture below. You'll know it is right because of the continuity between all of those cathodes (and you can see the traces).
Matt
and reference:
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Re: VVT ideas and testers
That's what I'm planning, although I'll replace the 1N004s with Schottky diodes. I have found those more effective in my other flyback circuits.y8s wrote:no diode necessary, just connect the cathode of one of the expander flyback circuit diodes to S12.
Matt