Conference terri::cars_uk

The graph and your interpretation seem wrong to what usually happens.

The norm is that the cold start valve is ON for the first xx seconds depending
on temperature.  For example, in my Alfa, the valve is open for max 4 seconds
with engine cold an 0 deg outside temp.  As the control module detects warmer
engine and ambient, it reduces the time the valve operates, being much more
sensitive to the former than the latter.  At normal operating temperature, the
valve is shut off completely.  Oh yes, it also is compensated for altitude,
although this is not a very common feature (?)

There must be a control module somewhere on the car.  Mine is under the floor
panel behind the passenger seat!  Keep looking - you've got a fault.  BTW, how
does the fule consumption look?  Running rich?

brian

    Hi Brian,
    
    Thanks for the quick reply. In answer to your question, fuel
    consumption is excellent, 32 MPG average (motorway, and into London).
    Mixture running at 1.4% CO (should be between 1.2 and 1.5 for
    manufacturers specifications). Checking exhaust colouration after long
    motorway run (on leaded petrol) shows a perfect slate gray coating on
    inside of exhaust. Mixture is pretty good I reckon.
    
    Definately no electronic control module for fuel injection. The entire
    system is made up of vaccuum switches, thermo-time switches etc that all
    interact to produce the desired affects. There is an electronic
    ignition module, but that has nothing to do with the fuel injection.
    
    The way you describe the injection in your Alfa makes a lot more sense
    to me, and yet that graph (which I have seen in two manuals now) does
    seem to imply that the valve stays switched off for a while at certain
    temperatures.
    
    Any more ideas, thanks,
    
    Mike
    
    PS. Is the Alfa a Bosch K Jetronic sytem ?

    
    V.A.G. have fitted these cold start valves to their cars for some time
    now.
    
    My Audi went through a phase were it decided "without warning" to
    activate the cold start valve...at normal running temp!
    
    The result was that the mixture was so rich it slowly "killed/starved"
    the engine. After leaving the engine off for 10-15 minutes it usually
    re-set itself, but I'd never know when this problem would occur again!
    
    The final straw was on the M8 to Glasgow one night, it was wet and windy
    when the engine began to lose power etc. After that it got a new valve.
    Needless to say it did the trick!
    
    The moral of this story is simple, after talking to the mechanics at
    Audi this problem is rife within V.A.G. DON'T mess about with
    it, get a NEW one....it ain't worth the hassle! 
    

The Alfa has a L Jetronic Bosch system.  Mr IRNBRU up in Ayr seems to have
the right answer.  Whatever is happening, sounds like your car runs fine
once the injector is disconnected, so there's obviously something wrong with
it or it's control circuit.

Brian

     I looked into how this works in my MK1 Golf, fitted with a Bosch 
     K-Jetronic system.
     
     The cold start valve is powered from the starter circuit, i.e. it only 
     squirts when the starter motor is cranking.  However the thremo-time 
     switch is in series to the cold-start 5th injector, so that it can cut 
     the circuit early if the engine is warm.
     
     I should think that it's very similar to your set-up.
     
     I've read about this problem in VW Motoring a while back, but can't 
     remember the actual cause.  Have heart, I don't think the fix was 
     expensive.  Will try to get hold of the article over the weekend.
          
     Robert.

In case you're interested, Dave Burden took the FI system out of his VW
completely and replaced it with Webers.  Works fine now, so he says :-)

     Is that those thirsty Webber 40's or the Webber Alphatronic Fuel 
     Injection System?
     
     8-)

>     Is that those thirsty Webber 40's or the Webber Alphatronic Fuel 
>     Injection System?


Dunno - write to him at OASS::BURDEN_D   He uses the car for racing ....