RE: How To Test A 75TS AFM?

["Masters, David DJ" <Masters.David.DJ@xxxxxxxxxx>]

Fool Injection 101.

Clean everything first!
I am heartened to see that everyone isn't advocating the total replacement
of all components including the ECU, so that is great.

Try this:
Clean the battery terminals, that is good for 5 HP
Clean all the earths on the engine and grill brace
Clean all the Bosch connectors (AFM, TPS, Idle Stabliser, temp sensors, etc)
Clean the connector to the computer
Clean the 4 relays in the engine bay

Then, recently I have added these steps:
disassemble the intake to the butterfly,
Use contact cleaner or equivalent to wash out the flap are of the AFM, and
the Idle stabiliser, (the round thing on the RHS of the plenum).  Clean the
intake tract, and around the butterfly.
Remove and clean the vapour separator. (Fill it up and soak it in kero or
something similar.)

That ought to do it!

For extra credits you can connect a DVM to the output from the O2 sensor and
check your voltage oscillates, but they tend not to be a problem.

YMMV, etc.
> Hi,
> 
> I'm experiencing about the same problem as you do. It has so far been a
> nightmare to track down. Everything I've tested seem to work fine :-(
> 
> > I am still trying to track down a sluggish acceleration 
> > problem on my 75
> > twinspark. Can anyone tell me how I can test the air flow 
> > meter? I have
> > tried a multimeter on the unit to measure the resistance and 
> > manually moved
> > the airflow flap. It appeared to have a linear resistance 
> > increase up to a
> > certain point, but then the resistance went funny for a bit and then
> > decreased in resistance as the flap was moved further. Does 
> > anyone have an
> > idea of what the resistance range should be like?
> 
> Been there, done that :-)
> Thing is, you have to have it connected with ignition turned on. Then you
> measure voltage between the connectors. It should change in a linear
> fashion.
> 
[]  Agreed, but they are  Bosch and very reliable.  See cleaning above. > 
> > Also, a stab in the dark. The engine is running very cool 
> > (approx 60 degrees
> > Celsius when fully warmed up) according to the temperature 
> > gauge and I think
> > either the temperature sensor or the thermostat is faulty. 
> > Could the engine
> > running cooler or the temperature sensor upset the engine 
> > management system
> > and possibly cause this sluggish problem?
> If it's the thermostat, I think it will still run pretty well since the
> EFI
> can adjust for a true temperature.
> If it's the temp. sensor, I think the EFI would adjust to the slightly
> rich
> side. I'm not sure of this, but I think that the air/fuel mix difference
> between 60 deg and 80 deg is too small to cause a noticeable
> "sluggishness"
> (sp?)
[]  A fair comment, however I have found that the thermostats do fail, and
even though they are not "normal", an aftermarket one can be purchase that
is made by the same company that ALFA use.  Really easy to change over.
> > 
> > The odd time that the engine doesn't accelerate sluggishly, 
> > the old girl
> > (152k) gives you a decent kick in the pants, so I know it has 
> > it in her. Any
> > help with this problem would be greatly appreciated.
> 
> It is always interesting? to start her up in the morning and see which
> mood
> she is in today, bears some resemblance to the female sex, doesn't it ?
> :-)
> 
[]  That's why I buy them!

Cheers,
david masters
ALFA75 TS , 1989 model.  130K kms.  Runs beautifully, never paid for a tune.

> /Anders Nilsson
> - -90 75 2.0TS with 174.000km and rolling
> 
> -

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