L-jetronic mods

[Bruce Plecan]

While lots of folks laugh at Fiats, they happen to be very well designed,
for what they are intended to be.
Anyway:
My suggestion is go to a junk yard and snag a 1227749, and just start with
that.
The Bosch while nice is going to get rare, and the Air Door will jam from a
back fire (just a matter of time, IMHO).
  The 1227749 is what is used in the GM syclones, and uses a 2 bar
calibration, MAP sensor, so you don't run out of "table space".  There is a
$15 prom editor at the syty home page..
  By using the Sunbird chip it's for 4 cylinder to begin with.
  Can be wired for P+H, or Saturated injectors.
  Other than checking to see if the TPS is a 0-5v signal, and VSS
compatability,
might be easier then where your headed..
  I'm not in favor of hammering the calibration from NA to 7 PSI,
Doc



> Hello. I'm new to the list (sort of), so forgive me this subject has been
> covered before.
> I installed a custom turbo system on my 1980 Fiat Spider. Building the
> system was a task itself but getting the engine to resist detontation has
> been an uphill battle. If detonation is as destructive as what everybody
> describes, then my engine would have been toast months ago because my
> engine has shown no ill effects. So far anyway.
> I had been running a few band-aid solutions such as water/alcohol
> injection, timing retard, etc. but these are getting old. My real problem
> is fuel enrichment.
> Here's some specs:
> 2 liter/twin cam/hemi design
> C/R: 8.1:1 (factory), current unknown, head was resurfaced during the last
> rebuild.
> Bosch L-jetronic fuel injection system w/lambda sensor
> Turbo: Rayjay 301
> Boost: 7 pounds
> gasoline : 93 octane (of course)
> Fuel enrichement device, rising rate fuel pressure regulator and a 2nd
cold
> start valve mounted upstream triggered at around 2 pounds.
> With these specifications, this engine should handle 7 pounds of boost
with
> no problems. That is with proper fuel enrichment, but I can't figure out
> how to get more fuel into the engine.
> The most frustrating thing is, the potentional is there, I just don't know
> how to unlock it.
> The other day, I was able to trick the computer into dumping more fuel
into
> the motor than it could handle, to the point the car was smothering and
> belching black smoke out out the exhaust at 7 pounds. The engine seemed to
> handle the extra amount of fuel until the contacts in the throttle
position
> switch closed and dumped too much fuel.
> I did this by installing a set of boost switches which adds resistance
> (about 2000 ohms) between the computer and coolant temperature sensor.
This
> doesn't work on my car because I've got a rising rate fuel pressure
regulator.
> My latest experiment was to splice a Hobbs pressure switch between the
> oxygen sensor and computer. As soon as I hit boost (.1 pounds) the control
> loop is disrupted.
> Today the temperature was near 80F and the car seemed to do OK.
> Can someone tell me this:
> I was under the impression that when the engine is under wide open
> throttle, the throttle position switch breaks the control loop. Is this
> correct?
> Or no matter what, the engine is still in the control loop?
> My theory is that any attempts to get more fuel into the engine are being
> overiden by the oxygen sensor even under wide open throttle, but by
> breaking the control loop, now I can get more fuel into the engine.
> Seems like my latest attempt has worked by I would still be more
> comfortable knowing that I am getting the most fuel I can get into my
motor
> without causing the car to choke.
>
> Here's a rundown of my current setup:
>
> 1) rising rate fuel pressure regulator
> 2) 2nd cold start valve mounted upstream before the throttle body
triggered
> at around 2 pounds.
> 3) Oxygen sensor to computer broken at .1 pounds
>
> I would like to do away with the 2nd cold start valve and use the
injectors
> as my sole source for fuel because I know they have the potential when the
> fuel pressure is stepped up.
>
> Also I want to point out that during the experiment where I got too much
> fuel into the engine was done with the 2nd cold start valve disconnected.
>
> What could I do to increase the pulse rate of the injectors? My attempt to
> create my own boost switch didn't work. I tried rigging up another
pressure
> switch with several rated resistors (600-1000 ohms) in parallel but the
CPU
> didn't like this.
>
> Also is there anything to my latest experiment by breaking the circuit
> between the oxygen sensor and computer under boost?
>
> If you guys need anymore details, just email me.
>
> This fuel injection system has been around for 25 years so I am sure there
> is someone on here that knows how to trick this system.
>
> Should I just have the injectors remapped to flow more fuel and run a
lower
> fuel pressure so the engine won't run rich at idle and cruise?
>
> Great Scott! I'm running out of options here. Someone help me!
>
> Thanks.
>
>
> ----------------------------------------------------------
>
> James Seabolt -----> mailto:jseabolt at intermediatn.net
> Webpage: http://users.intermediatn.net/jseabolt/
> ICQ # : 7344463
>
> United States
>
> 1980 FIAT 2000 TURBO Spider injected (John Deere aspirated)
> 1981 FIAT 2000 Spider (Rest in Pieces)
> 1981 FIAT X 1/9 (Injected)
> 1994 JEEP Wrangler (2.5l )
> 1976 Chevrolet Pickup (454 Big block/7.3 liter)
>
> ----------------------------------------------------------
>