Megasquirt 18rgeu ignition problem

[jabbatron]

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[thechuckster]

i ran msextra code on my old RA40 - older ECU and firmware but had the bits ready to upgrade.

when cranking, it's sticks to a fixed advance until the ECU thinks it's running (>300rpm from memory). That fixed advance is set in the 'More Ignition Options' dialog box (see here for more info).

note: you need that trigger signal coming in about 60 degrees before TDC (and the trigger angle set accordingly in the 'Ignition Options' dialog box). The stock position of the VR sensor in the dizzi may not be ideal - you'll have to reposition and lock the sensor mounting plate. You can't just rotate the dizzi rotor/drive as you may end up with the rotor too far away from the spark terminals in the dizzi cap.

note: the spark mode you want is 'Basic trigger'.

I wouldn't try to set the trigger angle based on cranking signals - get it idling (somehow, get the timing locked to 10 BTDC, get the idle AFRs right, then focus on fuel tuning).

I also had it skip at least 3 (or more) trigger signals (the longer cranking period gets more oil circulating - or at least that was the theory). I also managed to get the polarity of the VR sensor around the wrong way - easily checked with 'scope, or also noticable your trigger signal suddenly shifts back in time at approx 3k rpm.

edit: setup notes for ms1extra:
Setup - VR sensor
1) Set the crank at 20BTDC
3) Make sure the rotor arm points towards the correct contact in the distributor cap
4) Bolt down the distributor
5) Turn engine backwards until the pip lines up with the VR sensor
6) Measure angle BTDC (+/- 10 degrees is good enough) at the crank
7) Enter measured angle in "Trigger angle" of Spark Settings
8) Enter "Fixed angle" to 10 degrees this tells the ECU to ignore the spark map and hold it to the Fixed Angle.
9) Start the engine
10) Adjust "Trigger angle" until the timing light is at 10 degrees
11) Set "Fixed angle" to -10 , this tells the ECU to run from the spark map again.
12) Start tuning

[jabbatron]

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[thechuckster]

more detail on how you've wired up the coil would be handy - are you using the IGBT that's on the ECU to drive the coil?

[jabbatron]

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[jabbatron]

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[jabbatron]

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[o_man_ra23]

What wire are you running from the ECU to the VR?? Is it a shielded cable separate to the rest of the loom??

I found my signal jumped about a bit, and am going to a trigger wheel to remove the slop in the dizzy.

[jabbatron]

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[thechuckster]

shield has to be connected at one end only, otherwise it won't act as a shield

also, shield is not the return earth for the VR sensor.

[thechuckster]

would suggest installing megatunix tuning software (there's PC version as well as the linux installs) as it has a trigger logger tool - handy for looking at the signal(s) coming to the ECU.

[jabbatron]

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[jabbatron]

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[thechuckster]

tuner studio = buyware v/s megatunix = free & open source

I'd check your wiring - it will either fire both banks together (batched) or separately (bank) - unless you've somehow enabled staged injection (which is not what you want unless you have two rows of injectors).

[3jcelica]

Jabbatron,

megatunix with its tooth logger will help determine vr sensor wirring, as thechuckster say it should run ok to 3000-3500rpm ok and then break down if wired the wrong way, and then just switch the wires.

Do you have the ignitor signal inverted on non inverted with the BIP373? Check you are getting injector signal with a logic probe on all injector connectors, pull plugs to determine suspect cylinders, if you have injector signals and you are getting sparks I would suspect blocked injectors.

Thechuckster,

You stated shield is not the return earth for the VR sensor.

I use a loom from Diy autotune which is quite good with great colors and labeling on the insultation, The ignition wire they provided is high quaility single core shielded, I run the single core as the positive and the shield as the negative as suggested by diyautotune and the megamanuals, runs fine, however I can understand what you are saying, do you suggest I run dual core with a shield? and run the shield to pin 7 (ground pin) and say negative vr to pin 2 (ground pin). It is difficult to find good shielded cable is audio cable sufficient?

Thanks Roger