gems v8 flywheel triggering

[Seight-v8]

hello all,

So again gone back to basics with triggering my v8, as its still not running.

From the LR manual about the GEMS flywheel the missing tooth is set at 20deg AFTER TDC.

But i the meantime i noticed that the flywheel teeth/gaps are different.

So i have 36-1 ring in the flywheel, each gap is 10deg, and each tooth is only 2.75 deg....

Now i am more confused...as all other trigger rings i have seen have equal gaps/teeth.

So can i configure my vems to take account of this flyweel, and would it be worth removing the pickup ring and setting it at 90deg BTDC.

Really struggling here, to get my head round the triggering.

any help appreciated.

scott

[rob@vems.co.uk]

Basically the triggering chip (LM1815) fires when the VR sensor voltage crosses zero from a positive value, so as long as the teeth are regularly spaced, the width should not cause a problem.
What is the exact problem that you're having?
If you are getting a clean RPM signal then the trigger setup is fine.  If you are getting trigger errors then we need to know where abouts these are occuring in the hope that we can identify a cause.

[Seight-v8]

rob,

i've had it firing up to about 500 rpm....just wont run any futher.

Looks like no trigger errors when i looked at the log from megatune...so guess its reading from the flywheel cleanly.

Just drawn down the triggering/firing order on some paper, so i can try and understand it better.

Looks like i should now be using tooth one (60deg BTDC) on cylinder 8...

Going to set it in ecu then check timing with light to see if its correct for cyl 1.

Then i can move on to fuelling.

cheers

scott

[rob@vems.co.uk]

You need to be logging your start-ups so you can see what's actually happening with the various pulses.

[Seight-v8]

rob,

I've been logging, but struggling to understand what it all means...

And finding out whats wrong is like trying to read a foreign language.....not easy when your new to it.

got megalogviewer now....so makes better so see on screen.

Just seam to be getting nowhere fast.

scott

[gunni]

Load your config and the drawn view of the crank sensor setup.
It does sound like it´s not really right to have it 20deg ATDC.

Should really be more then that.

[Seight-v8]

The pickup is interal to the rear of the flywheel, as was made supplied by land rover, as i orginially planned to use the full GEMS efi system.

If i have known it was only 20 ATDC when i put the engine together, i might have thought about changing it.

But now it would be engine out to change it round to 90 BTDC.

Will see what happens tomorrow with checking the timing.

cheers

scott

[Tony C]

why not just fit a 36-1 trigger wheel on the crank pulley mate,
make your life a bit easier then,

[gunni]

The pickup is interal to the rear of the flywheel, as was made supplied by land rover, as i orginially planned to use the full GEMS efi system.

If i have known it was only 20 ATDC when i put the engine together, i might have thought about changing it.

But now it would be engine out to change it round to 90 BTDC.

Will see what happens tomorrow with checking the timing.

cheers

scott

you may be able to move all the outputs over one cylinder.
That way it might rather work after looking at the position of the TDC, missing teeth and what is the next piston in the firing order.

[rob@vems.co.uk]

Change the trigger tooth and index the engine to start with your second cylinder pair.

[Seight-v8]

so been a long day....and more questions thans answers.

Started and checked the timing at tdc so now got these as correct figures via timing light

TDC after the trigger = 50deg
first trigger tooth = 1
next trigger tooth = 9
crank advance = 12deg

So timing checked out and now works.

Still on cranking just popped & banged through exhaust, tried altering crank pulsewidth array various times, from 100 to 450%.... nothing but firing loud bangs through exhaust.

After 3hrs on changing/altering and getting nowhere....one last attempt i did this.

I had set in the ecu the following firing order, 8,4,3,6,5,7,2,1, as i could not use cyl 1 as missing tooth is 20deg ATDC on this cylinder, ignition was set accordingly.

Nothing but pops/bangs.

So then a ray of light came...changed firing order to 5,7,2,1,8,4,3,6 as cyl 6 would also be at TDC, then changed ignition to suit this new order.

Anyway.....lumpy but will run over 600rpm, with some throttle...but starts first time....although plugs are wet.

So anyone know why...this order works???....as i am confused as hell by now....but really glad is now working ish....

Definatly need some beer after todays hard work...

cheers

scott

[rob@vems.co.uk]

Its all down to what you think is the firing order, the position of the trigger and how things are actually set in relation to it all.
You were effectively 360 deg out of a 720deg cycle - its easily done.

[Seight-v8]

gonna try and set some fuelling tomorrow....

Just done a new VETable as old one didnt look right and also turned of MAT depandant retard...for now....

as table didnt look right...and the log showed the timing to be jumping around a bit.

still dont know though what my cranking fuelling should be...yet.....

getting there now....lol.....the long winded way.

scott

[rob@vems.co.uk]

mate its long winded but its the way everyone starts, these are hard earned lessons but worthwhile.

[gunni]

I´m going to have to agree with Rob, this is the better way to learn,