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 Post subject: Re: Developing an ecu ?
PostPosted: Tue Jan 29, 2013 10:35 am 
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Joined: Sat Sep 02, 2006 3:13 pm
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Location: Bournemouth
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Does anyone know the convention (not just Toyota) for cam trigger pulse ? Is it tdc no. 1 firing or no 1 intake ?

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 Post subject: Re: Developing an ecu ?
PostPosted: Tue Jan 29, 2013 1:03 pm 
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Joined: Thu Jul 14, 2005 12:44 pm
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Location: drinking devil fuel
Car Model: ST205
Does it really matter what physical cylinder it is?
It only defines a point in the firing sequence which the user maps to the actual cylinders

For eg, say it was physical cylinder 3 on the 3S. All it means is your firing order is defined as 3421


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 Post subject: Re: Developing an ecu ?
PostPosted: Tue Jan 29, 2013 1:18 pm 
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Location: Bournemouth
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It doesn't, but people normally start at 1 when specifying a firing order, hence it would make sense to stay with this in the configuration.

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 Post subject: Re: Developing an ecu ?
PostPosted: Thu Jan 31, 2013 2:06 pm 
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Location: Bournemouth
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Just a quick update. I haven't spent much time on it as I've the usual end of month rush but progress is reasonable.

Got the 'output compares' working so I can drive the injectors with hardware timing for very accurate fuel control (1.5uS accuracy)
Got the I2C working in order to write to the D-A to set a sensible level for the trigger signals (default on the d-a was 'switched off')
Made a test rig, shown below, to feed trigger signals to ECU. (I will connect the dizzy to a motor driven from a variable power supply for easier use)
Sussed out the interrupts on the processor for the cam & crank trigger signals.
Written the interrupt routines to measure RPM, drive the injectors in correct sequence for a time set in the main loop (currently fixed, will be output from map & corrections), drive the ignition according to precharge and 'fire' points specified in main loop. (currently fixed, will be output from map & corrections).

Still to do before it runs an engine (only a few hours work away now for crude running on fixed timing, fuel set from MAP sensor only).
Make up adapter loom from standard toyota plugs (which I now have) to the D connectors.
Fit the remaining injector drive transistors & diodes.
Get the A-D up & running to read MAP sensor (and others)
A few more sums for ignition timing so I can set a fixed timing of 20 degrees (currently fixed time after 30 degree trigger)
A few more sums to set fueling proportional to manifold pressure.

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To do before I can start running ECU in car to start building testing hours.

Add ignition and fuel map functions. Maps can be fixed in software initially (copy of my current link G3 maps)
Write initial software for slave processor to read temperatures and drive idle solenoid.
Get I2C comms running between the procesors.
Add coolant and air temperature correction map functionality.
Add idle control.

At this point the ECU should run the engine as well as my current link G3, without knock control or any of the other safeguards I will be building in. Target for this is end of March still.

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 Post subject: Re: Developing an ecu ?
PostPosted: Thu Jan 31, 2013 8:27 pm 
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Joined: Wed May 27, 2009 5:02 pm
Posts: 40
Car Model: None
do u consider adding a flex fuel sensor in the future, and multi maps... or it will be simple but effective toyota specific ems, sorry if i did not read the answer some where up in the text.. ?

and what are your views about link g3/4 in general on toyota cars, i am i process of mount the g3 updated to g4 in tho my st165 so looking for any helpful infos....
thx...


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 Post subject: Re: Developing an ecu ?
PostPosted: Thu Jan 31, 2013 9:37 pm 
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Joined: Sat Sep 02, 2006 3:13 pm
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Location: Bournemouth
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There are several 'spare' inputs which can be configured for various things. I personally regard the lack of fuel pressure monitoring as the greatest omission from the standard Toyota system, as any blockage or pump failure (including electrical drive failure) WILL cause lean running and likely engine destruction.

I am planning to have at least dual maps, if not more. In my case, I run LPG on a separate map with more ignition advance and correction for the poor fuel map transfer of the LPG ECU.

For me, the G3 works well without the intermittant misfire problem reported by many (all those were installed by the same person as far as I'm aware). It has a number of limitations in my view:

No sequential injection. Only 2 injector outputs mean some cylinders hve different injection timing to others. (I will be studying the effect on emissions & ecconomy on my ecu as it will be variable). Also means you can't have individual cylinder trim to account for manifold flow variations.
Massive lack of inputs, especially digital.
Lack of knock control of any sort. Means a responsible mapper will keep well away from detonation, losing power & ecconomy. An irresponsible one will get great results & write ups in forums, but leave a string of engines with failed ringlands. The same is true of most 'bugdet' ECU's of course.

I have no experience of the G4, but have heard good reports and I think it adresses all the above issues.

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 Post subject: Re: Developing an ecu ?
PostPosted: Thu Jan 31, 2013 9:42 pm 
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p.s. if you're putting a G3 into a ST165, you may find the following helpful. I should update the thread as there are a couple of inaccuracies / incomplete information as I wrote it prior to the install.

viewtopic.php?f=1&t=5454

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 Post subject: Re: Developing an ecu ?
PostPosted: Thu Jan 31, 2013 10:41 pm 
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Joined: Wed Jul 13, 2005 12:14 am
Posts: 3265
Location: Camberley, Surrey
Car Model: ST205
The Link G4 can do knock control but only via an extra add-on box which is another chunk of money.

Looking at different options for my car at the moment. :)

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 Post subject: Re: Developing an ecu ?
PostPosted: Tue Mar 12, 2013 9:00 am 
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Joined: Fri Jan 29, 2010 10:39 pm
Posts: 514
Location: Bournemouth
Car Model: ST205
How is it coming along?

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 Post subject: Re: Developing an ecu ?
PostPosted: Tue Mar 12, 2013 9:49 am 
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Location: Bournemouth
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Semi shelved at the moment. I will probably only be going as far as providing myself with ecus for my own cars.

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 Post subject: Re: Developing an ecu ?
PostPosted: Thu Oct 24, 2013 12:42 pm 
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Joined: Sat Sep 02, 2006 3:13 pm
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Location: Bournemouth
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Just seen this link posted on the MR2 forum. Seems someone else had the same idea as me.

http://twosrus.com/catalog/product_info ... cts_id=853

Doesn't seem to make a feature of knock control, just states it has a knock sensor input and headphone output to listen for knock while tuning.

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