Miata Mailing List: February 1999, Message #141

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Mike and the list: I don't post to the list much but I have a BBR with an
auxillary ECU which is programable.  It plugs into the stock 1.6 ECU and
controls virtually all engine functions except for idle which is
controlled by the stock ECU. It was programmed by Ken Brittain at BBR.
I've checked it with a Link A/F meter that I got from Bill and it never
runs lean on boost until you hit 11 lbs which is probably due to a
limitation in the flow of the stock 1.6 injectors.  Yesterday it was about
35 deg in the New York City area and it did 50-70 mph in 4th gear in about
3.2 sec which is getting up there.  However, I'm a little nervous to push
it when it get close to 11 lbs because the A/F mixture can suddenly go
lean.  I could replace the injectors with 1.8 230 cc injectors or RC's 250
cc injectors.  Is the increase in boost that I would be able to run safely
before the A/F mix would become lean just of functon of the ratio of the
230 or 250 cc injectors to the stock 1.6 injectors or a more complicated
function.  I've heard that the 1.6 injectors are either 195 cc or 205 cc
and am not sure which is correct in my Sept 89 Miata. If the larger 230 or
250 cc injectors are used is it possible to adjust for the idle by
adjusting the the A/F meter without re-programing the ECU?  The auxillary 
ECU controls pulse width and is programable (it was programmed by BBR) but
I'm not sure how to do it.

Thanks,  Herb Samuels 

On Mon, 1 Feb 1999, Mike Marzalek wrote:

> 
> I'm a bit surprised that this works.  On my stock 1.8 ECU, the airflow
> signal has changed by a huge amount with the addition of a turbo and
> different levels of boost, yet the ECU still puts out virtually the same
> fuel injection pulse width/duty cycle at WOT.  The engine gets the extra
> fuel it needs because of the VFPR.  Maybe 1.6 ECU's or non OBDII ECU's are
> different.  Or maybe it doesn't work at WOT.  That's the problem with
> reverse engineering - not that I haven't done my share :-)  YMMV
> 
> Mike Marzalek
> mikem@sr.hp.com
> '96 red aerodyne
> Sonoma County, Ca.
> 
> << Bob at Link made a fantastic new product call InterceptLink. It basically
>  will turn a regular ECU into a programmable ECU (well almost). What it does
>  is intercept the signal from the airflow meter and alter it as we program
>  before sending the signal to the ECU. It work like the  Apexi Super AFC but
>  in 3D mode. So if you've done all that and need more fuel the InterceptLink
>  is the perfect answer. It will require the keypad to program.This product
> is
>  also price very very competitively.
>   >>
> 
>