Hi Daim

If I wasn't so snowed under, I'd try and help you more but why don't you put my Photo up that you put your notes on.

Then maybe someone may know the answer to what you are trying to find out.

 

Yes. It goes from a vacuum source....not sure which one....to the Marelli ECU


I hear ya.

Cheers
DD

 

Ah, yeah, I now remember... Behind the dash or somewhere beneath it was the Marelli ECU with a vacume connection. That would be the black rubber hose connected to the bulk head. The heating system aka AC uses a red plastic tube... Which get's it's vacume from the little solenoid which, like in Volvo terms, must cut the vacume supply to the AC system in case of a full throttle position where there is no vacume in the intake manifold...

The Marelli will always get it's connection and needs to know if full vacume (idle) or partial (normal driving) or none (full open theottle) to adapt the ignition...

Finanly it makes sense... Until someone comes and ruins it Meaning the blue valve only works for the AC, the front take off goes straight to the cruise bellows and the rear take offs being for Marelli, tranny and climate control with vacume switch and full load switch...

 

Hi Daim

Tracing all those Vacuum Pipes would take me time that I don't have at the moment, as they just seem to disappear at the back of the Firewall.

I've got to get my own Car done, while the Weather is good, as its usually chucking it down with rain at this time of the Year.

Hope you understand about that, as it would take me a lot longer than you would think.

But as with Doug, I do share that frustration.

 

All OK OB.

Just thought as you have the exact same setup as I do, that it would be a 5 min thing but never mind. I've basically sussed it now...

 

I'll always allow the possibility that I'm wrong but I really don't think the blue solenoid solenoids(s) have anything to do with the climate control.

My '88 V12 had the two blue vacuum solenoids and the MKIII climate control (as does your '89) and neither were related to the climate control.

The climate control uses a black/white check valve to take care of the full throttle thing....at least on every V12 I've touched.



Right, and that should be a red plastic vacuum tube, thin. But maybe there's more than one red vacuum tube? That much I don't remember.

Cheers
DD

 

Is that the white/grey and black cylindrical valve under the right intake?

 

I don't think that's it. That sounds like one of those delay valves.

The check valve for the climate control vacuum is either near the vacuum reservoir or near the bulkhead where the climate control vacuum hoses go through.

(I might be getting Series III V12 stuff mixed up with XJS V12 stuff!)

On my Series III V12 the check valve is hear the bulkhead/firewall

Is yours a German market car?

Cheers
DD

 

It looks to me to be the solenoid for the 45 second timer.

The 45 second timer opens this solenoid to vent vacuum capsule to atmosphere the same timer circuit opens the Suplemental Air Valve.

No?

 

My car doesn't have a vacume tank... And is a UK special with no emissions stuff what so ever...

 

I was referring to the vacuum advance capsule. Or is yours a Marelli?

If you have the timer for the 45 second supplemental air valve at start then this system would also activate the solenoid to dump vacuum from the Vac adv capsule to eliminate advance at startup. This helps heat up the O2 sensors more quickly.

 

I have the Marelli setup and also NO O2 sensors...

 

You should have two vacuum tanks, though. One for the AC and one for the brakes


Cheers
DD

 

Nope. No vacume needed for the ABS system. And I don't have any vacume pot in the engine bay...

 

ah, of course. You already said as much. My excuse? It was middle of the night.

ROW spec cars have a 15 minute timer and do the same as US models with that system but for different reasons.

 

Ahhhh, yes !




Ok!


Cheers
DD

 

I don't have that valve... EAC4012 was not fitted to non-cat UK spec Marellis...

 

I'm stumped, obviously. I think what this may come down to is to (somehow) trace down a vacuum schematic specific to your *exact* build specification. One has to exist somewhere.

On the bright side, you don't have the complex canister purge scheme, the even more complex vacuum advance system, cruise control dump valve, air injection diverter valve, climate control reservoir, nor brake vacuum assist. So, relatively speaking, you have it easier that many

Cheers
DD

 

Yeah, easier is of course great, if only it would be clear WHAT the blue solenoid actually DOES do...

I have the same connection on the A bank throttle body which runs forwards, then under and goes into a grey and black one way valve. This then leads to the blue solenoid and is switched... The metal tube of the solenoid also connects to the intake manifold (rear). The 90° connector goes somewhere else and as far as I can tell, into a red plastic tube which heads to the left side of the car (most probably to the glove pocket where the Marelli ECU sits). But why would this need to be switched!?

The other connector as it looks deals with the switch on the intake (that plastic lump with two cables) and then to the AC system.

But again, WHY would the Marelli ECU need a switched vacume? Isn't it obvious that it needs a constant vacume supply which would let off at higher RPM and grow at lower RPM so it can determin if the timing needs to be retarded (like me ) or advanced (like everyone else )??

Anyhow, as it looks, the blue solenoid seems to be for the Marelli ECU.

 

As I said, I believe that the marelli ROW cars switched the vac off on startup. Why? Dunno. Obviously you'll want a diagram to clearly show that before setting it up.

I remove over the pic that had a random part outlined in red.