Re: O2 sensor & 75 TS

["Stephen Rodgers (ERA)" <Stephen.Rodgers@xxxxxxxxxxxxxxx>]

Hi Oleg, Dougal,

I have a '88 75 TS and can confirm that it is fitted with an O2 sensor,
presumably because this model (purchased in Sweden) is also fitted with
a cat.

I have also experienced similar problems. Actually, for me this problem
became more acute when the temperature dropped below freezing where the
engine even cut out for a few seconds indicating fuel starvation. I have
been through the same route as you Dougal including changing the engine
temperature sensor, all with only marginal improvement. After checking
the pressure of the fuel supply both before and after the regulator I
came to the conclusion that the regulator was at fault. Since changing
this performance has never been better.

Regards,
Steve.
'88 75 TS (Red)

>Oleg wrote:
>This is a very stupid question, and surely a FAQ, but I can't find the
>damned thing (O2 sensor) in my non-cat '88 Alfa Romeo 75 2.0
TwinSpark...
>
>The general sense is confused:
>
>1. No catalytical converter -> no place to screw in the O2 sensor
>2. Engine management is Motronic ML 4.1 -> operates Ok without O2
sensor ?
>3. Can't see any hanging wires...
>
>I wanted to check the voltage, but no place to connect :) Just
>sometimes/some rpm ranges
>the car is somewhat "sluggish"... Could be the engine temp. sensor too?
>(at the back of the engine block)

>>Dougal wote:
>>My 75TS doesn't have an O2 sensor either. However, the manual I got
from
>>Charters in UK doesn't show an O2 sensor. I think the O2 sensor was
not
>>used on the 2L Twinspark engine only on the V6 ones. I may be wrong.

>>However, I also have the sluggish performance problem at differing
times.
>>Sometimes when I accelerate I get a good kick in the pants from the
old
>>girl, but other times she's really dead. What I have tried so far is:

>>Dismantled the airflow sensor and cleaned the potentiometer and check
its
>>resistance. Also, checked the air temp sensor in the meter as well. I
am
>>still wondering whether the airflow sensor is faulty as when measuring
the
>>resistence and moving the airflow flap, the resistence increased until
the
>>flap was half way open and then the resistance started decreasing
again. It
>>doesn't seem normal to me. After cleaning the potentiometer the
resistance
>>increased and decreased more smoothly. Perhaps some other digested
would be
>>kind enough to measure the airflow sensors resistance and advise how
their
>>resistance changes?

>>I have check the throttle switch and it seems fine.

>>I tried running the car on one coil and set of spark plugs at a time
and
>>the performance was pretty much the same with no missing, so they seem
ok.

>>I tried putting voltage on the valve timing advance solenoid and also
>>measured the voltage supplied to it at various revs and it all appears
to
>>be working fine.

>>My next step is to try fuel type problems. I put fuel injector cleaner
in
>>the fuel for a couple of tank fills and I got a marginal improvement.

>>I hadn't thought of the engine temperature sensor. I'll give that a go
too.

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