Jag V12 ECU Mods

[Tony Bryant]

> From:          "steve ravet" <steve at sun4c409.imes.com>
> To:            John Napoli <jgn at li.net>, diy_efi at coulomb.eng.ohio-state.edu
> Date:          Wed, 1 Oct 1997 12:03:47 +0000
> Subject:       Re: Jag V12 ECU Mods
> Priority:      normal
> Reply-to:      diy_efi at coulomb.eng.ohio-state.edu

> > A thread on another list describes the results of having a stock
> > Jaguar V12 ECU modified by an outfit in the UK.  The net of it is
> > that very significant performance improvements were realized.
> > 
<snip>

> > I would like to hear the lists collective thoughts on this 
idea.

The ECU on '81-'91 HE V12s is a bosch Digital-P. From the small piece 
of info I have gleaned on the subject, it is a digital version of the 
D-Jet. From all accounts it is pretty basic, and I have heard 
unconfirmed rumours that it doesn't even have a micro on board, just 
a ROM chip and a bunch of A/Ds and D/As and assorted analog crap.

The V12 injector wiring loom divides the 12 injectors into 4 groups 
of 3 (wired in parallel). However inside the ECU, these are connected 
together into 2 groups (like D-Jets). I believe this ends up batch 
firing each cylinder bank.

There is also separate wiring for the peak current and the hold 
currents (which go through a resistor). Bizzare to say the least.

When jag introduced the 6L version of the engine in '92 ?, it 
reportedly got 5MPG better enconomy (13-26MPG vs 13-21MPG - imperial 
gallons btw). One suspects they ditched the digital-P for something 
better.

> 
> One small bit of advice:  TPI engines aren't all sequential.  Some 
> are batch fire.  The '89 corvette, for example, had two injector fire 
> signals, one for each bank.  That could be extended to 6 injectors 
> per bank.  You might have to worry about increased drive current, but 
> you could use Sandy's driver board for that.  It's ready to go right 
> now.


> 
> Another choice is to transplant an entire GM V8 in there...  I'm sure 
> you've already seen www.jagsthatrun.com, but if not go give them a 
> visit.
> 
> --steve

Sacrilege! If you want a chevy, buy a chevy. We don't want no 
steenkin pushrod lumps here :-)

'72 Datsun 510 EFI 
'71 Datsun 510 Twin SU
'85 XJS V12

$$$ MAKE CAR FAST $$$
bryantt at psc.fp.co.nz