Author Topic: A couple of questions  (Read 7330 times)

Offline Jiff Lemon

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A couple of questions
« on: February 22, 2008, 03:48:11 pm »
Trying to digest as much as can reading the manual but I figure by the time I've read and re-read it, someone will probably have the answers already!

Planning on running a Vems on a V6, wanting sequential ignition and fueling.

So, I think I need a crank sensor and a cam sensor to acheive the sequential part but, do a 2x cam sensors or just the one?

Similarly, do we run 2x knock sensors (current engine has 2 already, one per bank) and 2x wideband?

Offline rob@vems.co.uk

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Re: A couple of questions
« Reply #1 on: February 22, 2008, 03:56:37 pm »
What engine is this on?

You can get sequential injection and wasted spark on a crank trigger alone, but if you want sequential ignition you'll need a cam sensor - but only one is needed.

Two knock sensors are supported, but the twin wideband control is not available - we have the electronics in there to drive the two sensors but the processing required and fuel trim is so problematic its not being developed any further.  What many of the V8 people do is to have a Wideband and EGT gauge for the second bank so that they can monitor things that way.

Cheers

Rob

Offline Jiff Lemon

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Re: A couple of questions
« Reply #2 on: February 22, 2008, 05:09:33 pm »
Cheers rob - clears things up! Shall continue researching and drawing up my parts list.

Engine is Toyota's 3 litre 3vz-fe.


Offline rob@vems.co.uk

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Re: A couple of questions
« Reply #3 on: February 23, 2008, 10:22:56 am »
Is that the 12 crank tooth one? If so we need to use one of the cam Ge sensors.

Offline Jiff Lemon

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Re: A couple of questions
« Reply #4 on: February 23, 2008, 01:41:28 pm »
Nah the 3vz is the earlier engine; No crank sensor, just a dizzy - suitable perhaps for cam position sensing?

May be able to source some triggering bits from the later 1mz engine though, but I'm also thinking fabricating a trigger wheel and using standard sensors may be easier than trying to make the ecu work with toyota parts?

As a see it, I need:
Crank sensor
Cam sensor
Engine temp
Map sensor
Engine air temp
Wide band sensor

As the later 1mz are still air flow meter design, it kinda makes sense to start with a clean slate.

Offline rob@vems.co.uk

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Re: A couple of questions
« Reply #5 on: February 24, 2008, 02:35:15 pm »
Nah the 3vz is the earlier engine; No crank sensor, just a dizzy - suitable perhaps for cam position sensing?

May be able to source some triggering bits from the later 1mz engine though, but I'm also thinking fabricating a trigger wheel and using standard sensors may be easier than trying to make the ecu work with toyota parts?

As a see it, I need:
Crank sensor
Cam sensor
Engine temp
Map sensor
Engine air temp
Wide band sensor

As the later 1mz are still air flow meter design, it kinda makes sense to start with a clean slate.

Those cam triggers are as noisey as hell Irishtwincam and I wasted a reasonable amount of our lives last year in car parks trying to get his 4A-GE dizzy sensors to make some sense.
Fabricated trigger wheels can be a pain too as issues with the wheel's runout can make trigger errors occur at strange places, so I always advise going OEM if possible, followed by a tried and tested trigger setup.  A lot of the Mercedes lot use two steel bolts on the crank pulley 60deg BTDC and BBDC and a cam sync with hall sensors.

Rob

Offline Jiff Lemon

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Re: A couple of questions
« Reply #6 on: February 24, 2008, 09:39:05 pm »
well have since discovered that the 1mz has zero parts that are interchangeable so its fabrication time!

So, ditch the dizzy, fabricate some form of cam sensor wheel - Do we just need a single reference point here or multiple ones?

Crankpulley; either weld on a universal 36-1 jobby or have a new pulley machined with a 36-1.

Obviously if I go down the weld on route I'll make sure it's straight and true, but as I've a friend who's terrible handy with a lathe, machining new is more likely.


Offline rob@vems.co.uk

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Re: A couple of questions
« Reply #7 on: February 24, 2008, 10:37:21 pm »
In the first instance I think you'd be best to use a proven pattern, 'home made' patterns are often a little too aggressively machined - the teeth are usually cut deeper than they need to be and you can run into problems with VR hysteresis.  Or

The thing to keep in mind with the LM1815 VR sensor is that it triggers when a positive voltage crosses 0 and goes negative.

Getting a working Hall trigger setup is less problematic from a noise perspective, but Hall either works, or it doesnt.

Eitherway I'd start with crank trigger first, and get the system running on wasted spark and sequential injection, then only if you feel you need to, worry about the cam sync.

Rob

Offline Jiff Lemon

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Re: A couple of questions
« Reply #8 on: February 26, 2008, 08:40:41 am »
Well I'd probably pick up a trigger wheel from www.trigger-wheels.com - They seem suitable?

I hear what you say about crank triggering and wasted spark first. Keep it simple first  ;D

Shall be posting a few more questions about "can it do xyz" soon....

Offline rob@vems.co.uk

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Re: A couple of questions
« Reply #9 on: February 26, 2008, 10:04:32 am »
I think we have a couple of systems running using these trigger wheels happily, they even say VEMS works with their trigger wheels:
http://trigger-wheels.com/store/index1.html

Cheers

Rob