[Diy_efi] Motronic fuel cut on excess boost??

[Steve Spiers]

Ive had a few Fiats that use LE, thes have a pressure switch too. there
seems to be 2 different types. 0.68 bar and 1.18 bar. these things are
massive, cant miss em. Interesting this is they only work in conjunction
with the MAP sensor in the digiplex. both need to be tripped to cut the
engine.

Steve

Kenny W wrote:

> Quoting Chris Wilson <chris at formula3.freeserve.co.uk>:
>
> > AFAIK it doesn't have a MAP sensor, works of AFM
> > (swinging gate type)
> > throttle pot and RPM, with normal temp trimming.
> > If it HAS a MAP sensor
> > I haven't found it! UK spec 1988 Volvo 740 turbo
> > intercooler, on
> > Motronic, the one with 2 flywheel sensors, one
> > counting ring gear
> > teeth, the other about 90 degrees BTDC ( a metal
> > tab on the flex plate,
> > it's an automatic). Cheers.
>
> Oh! And I meant to repsond to this because being a
> Volvo guy I actually know what you have to do! lol I
> got talking about sensor scaling and missed the point.
> Wouldn't be the first time.
> Anyways, there is a pressure switch that is set to
> about 14psi usually that cuts the fuel (simply called
> an overboost switch), no map sensor, just a "hobbes"
> switch thta triggers if you lose the wastegate control
> line. It is near the center console, almost near your
> feet somewhere on the driver's side of the car (oh, in
> north america anyways, hmm, may be pass side for you).
> Anyhoo you can track it down by pulling your boost
> gauge out and following the vaccuum line attached to it
> to the firewall. The fuel cutout switch is "t"'d from
> this line. So basically hunt around for vaccuum lines
> coming in through the firewall, there's a switch
> around. There is an adjustment on the switch, but it's
> filled with glue. Melt out the glue and tweak it, or
> buy an adjustable pressure switch from a parts store
> and wire it up in place of the stock switch (normally
> closed.
> Hope that helps. You can be glad to know it's not
> related to the ecm at least.
> -Kenny
> AKA Captain Bondo
>
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