RE: [T3] FI tuning question

["Fuhriman, Mark" <mfuhriman@fugro.com>]

Norman, I'm posting this to the list because I think others might
be interested...

When I got my FI car about a year ago, the FI was thrown together
kind of sloppily -- bad wiring splices, injectors wired wrong, bad
connectors, etc.  It ran fine, but the throttle response was
sluggish, I was running rich, and I developed intermittent missing
and starting problems.  All I did was read all the information I
could find on the d-jet system and work to put things back
together right.  That's all I meant by "tuning".  I run a stock
system, and I was not looking for any more performance than a
properly tuned stock system.  But by "tuning" things to how the
system is supposed to work, yes, I have indeed noticed performance
gains over what I had.  Here's a brief run-down of what I have
done to my FI in the past few months (not really in order):

-Reconditioned my FI wiring harness.  This included soldering each
and every "crimp-on" splice that others had done.  Also replaced
bad connectors with parts from junked harnesses.

-Cleaned up the distributor.  Cleaned up the FI trigger points.

-Using VOM, looked for incorrect wiring.  Found a few wires that
were not wired per the wiring diagrams, so I fixed those.

-Took the pressure sensor apart.  Found it full of oil.  This is
caused by somebody overfilling the aircleaner I'm told.  I
replaced it with a spare and I noticed a BIG improvement in
throttle response.  It was relatively sluggish with the oil in
there.  I drained the oil out of the old sensor and now it's a
spare.

-Tested the injectors to verify good spray pattern and consistent
output.

-Found my pressure switch (a 68-69 part) not working.  Hooked it
up it per manuals and got an immediate improvement in mileage and
cold running.

-Through much frustration and with List help, I traced my
intermittent missing/no-start condition to a bad ECU.  This was
complicated by the fact that my spare was also bad!  When I
finally tried a third, everything was finally fixed.

All that, in addition to regular valve adjustment and timing
checks.  Getting improved performance boils down to learning how
each part works and making sure that everything is hooked up
right.  I think I have read on the list that you can go up to
about 1700 cc engine with stock FI.  And that you could maybe go
bigger with Type 4 injectors.  Then of course there's Leon with
his "frankensteining" antics, but that's getting way out of my
league...

-Mark Fuhriman

> -----Original Message-----
> From: Roush, Norman [mailto:norman.roush@compaq.com]
> Sent: Thursday, April 12, 2001 10:20 AM
> To: 'mfuhriman@fugro.com'
> Subject: FI tuning question
>
>
> Mark,
>
> In your response to Drew Gainor's Carb vs EFI question you
wrote:
>
> Of course, I have taken the time to learn how the FI works,
> so I have tuned
> it to give pretty good and reliable performance.
>
> What was tuned and how was it done?  I have a '68 Sqbk with
> 220K miles which
> runs well and is very reliable.  I looked into rebuilding the
> motor with a
> bigger pistons/stroker crank/cam combo but was told the FI
> setup placed
> limits on how big the motor can be.  Since it wasn't broke I
> decided not to
> fix it but I am intrigued by tuning the FI if I can.
>
> Did you get much in performance gains by what you did?
>
> Thanks,
> Norman
>

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