Bosch Mono-Jetronic

[Wouter de Waal]

Hi all

I recently started looking at the FI system in my wife's Fiat Uno again,
after it developed a flat spot on accellerating.

The system consists of a single injector in the throttle body, an inlet air
temp sensor, a throttle position sensor, a servo to control the throttle at
idle (idle speed), a water temp sensor and a lambda sensor. And engine rpm
info is sent to the system from the ignition computer.

Question 1: How? As I understand things, you need to know the load on the
engine. How does this system find the load? Perplexing. The only thing I can
think of is that the mixture is controlled by the closed loop system, even
under acceleration etc. But would the lambda sensor be fast enough? Would a
slow lambda sensor then cause a flat spot? Ooooh, my head hurts :-)

Question 2: This thing has a diagnostic port, to be read by a "Fiat
something-or-other tester" which I obviously don't have. Seems to be
three-wire. Anybody know what the protocol is likely to be? Peter? Should I
put a scope on it and see what comes out? Should the ignition be on, or the
engine running, when I do this?

Thanks!

Wouter
--
Wouter de Waal ZS1KE  GE>AT d-(pu) s+:-- a- C++$ UL+ U*+$ P>++ L++ E- W N+++>++
Argo 505 / FT200      !o K w(--) !O !M V(--) PS+ PE++ Y+ PGP>++ t 5? X? R?
                      tv>--- b+++ DI+ D+ G e+++(*) h--- r+++ y+++(*)

'72 Puma - 1700 FI Type IV engine                          Perseverance my son,
'6? Series IIA SW - factory fitted Lucas immobiliser         it's a   Land/
                                                                       /Rover
"All journeys end when we reach our destination but the journeying
remains a thing apart, unique unto itself. Most of us make life's journeys
without understanding that the journeying is a separate thing." -- Bob Hoover