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Title: Digiplex 401a vaccum connection? Post by: 1970s wedge on July 10, 2013, 09:16:27 PM Could anyone help please? I have a 2 litre HPE ie unit in a 'Hawk' fitted with the digiplex 401a ignition module.
It has never given me any trouble and still to this day 'seems' to work fine? ( thats done it now!) My question is, on the standard car where does the digiplex take its vacuum signal from? is it A: the 4mm (?) union off the back of the throttle body? B: from one of the two 4mm unions on the plenum chamber ( which is where its connected at the mo alongside fuel pressure reg ). Also the water feed to the throttle body, is it for heating? or for cooling? I am considering disconnecting? if it is for heating? as I only use the car for 6 months of year! (the 6 warm months?). Thanks for the time given if anyone should reply its not urgent! ::) kev b. Title: Re: Digiplex 401a vaccum connection? Post by: MattNoVAT on July 10, 2013, 09:57:53 PM I thought on the i.e. the water feed to the throttle body was for determining engine temperature, similar to the automatic choke on the normally aspirated cars.
Sent from my iPhone using Tapatalk Title: Re: Digiplex 401a vaccum connection? Post by: millieman on July 11, 2013, 12:37:06 AM Hi the answer to the question is B next to fuel pressure vac.
Title: Re: Digiplex 401a vaccum connection? Post by: gengis on July 11, 2013, 05:44:55 PM Pretty sure the water feed to the throttle body is for heating in cold conditions, to stop fuel icing in the inlet tract.
Title: Re: Digiplex 401a vaccum connection? Post by: 1970s wedge on July 16, 2013, 10:26:38 PM Thanx for replies fellas x :D
gengis: confirms what I thought, may proceed with disconnect for minute bhp increase? (one less heat source heating up induction temp???) millieman: I will leave it there then! ( what is that little vacuum takeoff for then? its aperture sits under the throttle butterfly valves seat when its closed ie, at idle? would it not be a more sensitive/accurate control point for vacuum dependant devices?? (digiplex and FPR). MattNoVAT: Iirc on the 'ie' well on mine anyway fitted with Bosch L-jetronic the 'coolant temp' is read by a sensor positioned on the metal 'over head' coolant pipe right on its bend over No4 cylinder along side another sensor or thermo time switch? both of these are wired into the L-jetronics ECU? There may have been some type of 'thermostatic device' fitted to the TB's collant connections when fitted on the HPE to warm up the throtte butterfly when outside temps could lead to icing up of the TB but all such complicating plumbing was 'binned' when I dropped the lump in the Hawk :o. Thanx again for the time taken to reply to my question? hope youre all out enjoyin the rays in ya 'Italian marques'? ;D kev b. |