AAZ turbo vacuum pipes

[Al Housman]

Sorry if this is not the right forum but I'm sure somebody out there has dealt with this situation.

On the previous engine I had a pipe from the small connection on the inlet manifold to the top of the diesel injector pump, which seemed to work,especially with the boost pin I had fitted.

I've just had a friend help me fit (yet) another AAZ to my Syncro Doka. He spotted that there was no vacuum pipe going to the turbo so took one from the top of the diesel injector pump to the turbo, since he'd found a photo showing this. But this left the connection on the inlet manifold just sucking in air.

I have today connected to inlet manifold to the turbo and am convinced that it has improved acceleration and smoothness. BUT this leaves the top of the injector pump( and boost pin) without a connection.

Does anyone please have any helpful suggestions? I did wonder about putting a T in so that the vacuum through the inlet manifold could operate the turbo AND the boost pin. Or am I barking up the wrong tree?

Cheers

Al

[Dutchdude]

I struggled with the same thing. Turns out there are several different versions of the AAZ engine with different pumps: with and without LDA.

On the version without the pressure hose (yes it's overpressure from the inlet manifold generated by the turbo and not vacuum), the little pipe on the inlet manifold is blocked off with a small plug. The pump has a flat cap on the top and no connection for the overpressure hose. If you open the pump you will notice that the internals of the LDA are not there, no membrane, no boost pin and not machined, so you cannot convert them.

This version of the AAZ is called the ECOdiesel, it has a turbo but no LDA ("LadeDruckAnreicherung" in german, which I think translates to "boost pressure enrichment") this is a low emission engine. Only way to get LDA on it is to swap the pump for a different one with LDA on it.

Probably the easiest way to go is to mount the standard JX pump. The pump pressure head on the back is the same (9mm) and the LDA is separate from the pump so it will fit nicely under the engine lid. This has been done many times and it works very well since the pump has the same specs. Only thing you need to do is set the adjustment screw on the back of the pump.

Cheers

[Al Housman]

Thanks for that.

My pump has an LDA and I've fitted a more aggressive boost pin. I know that when I rev the engine there is suction through the small union on the inlet manifold. I had the LDA connected to this before but now that I've been told that the turbo needs to be connected to the LDA I've got a bit confused.

From what you're saying do I take it that the turbo exerts pressure on the LDA to move the diaphram and therefore the boost pin? It is a JX turbo which I had remachined to match the larger AAZ engine.

I may have misguidedly thought that the suction through the Inlet manifold union would cause the LDA to work. Does the union on the turbo have the same effect?

Do you think I'm best off connecting the turbo to the LDA, the LDA to the inlet manifold, the turbo to the inlet manifold, all 3 together or none of these? Sorry, it reads like some silly multiple choice school exam!!

Cheers!

[ELVIS]

Pipe from inlet manifold to top of pump, leave the turbo venting to atmosphere

[Al Housman]

Many thanks both.

Inlet manifold to LDA was how I had it on the previous engine. Oddly enough when I put turbo to inlet manofold it seemed to pull better (or maybe I just had the wind behind me)..All a mystery to me!

Cheers

Al

[Dutchdude]

The Union on the turbo is for the wastgate. I would not mess with that. So you're probably correct stating that your vehicle pulled better with the LDA connected to that, boot pressure probably got very high because the wastegate did not open when it was supposed to.

[max and caddy]

Thanks for that.

My pump has an LDA and I've fitted a more aggressive boost pin. I know that when I rev the engine there is suction through the small union on the inlet manifold. I had the LDA connected to this before but now that I've been told that the turbo needs to be connected to the LDA I've got a bit confused.

From what you're saying do I take it that the turbo exerts pressure on the LDA to move the diaphram and therefore the boost pin? It is a JX turbo which I had remachined to match the larger AAZ engine.

I may have misguidedly thought that the suction through the Inlet manifold union would cause the LDA to work. Does the union on the turbo have the same effect?

Do you think I'm best off connecting the turbo to the LDA, the LDA to the inlet manifold, the turbo to the inlet manifold, all 3 together or none of these? Sorry, it reads like some silly multiple choice school exam!!

Cheers!

If you have suction at the inlet manifold your air filter is blocked!

[Al Housman]

I only get suction when I rev the engine. Air filter is good.

So the LDA works with positive pressure pushing the diaphram down. Maybe I need to double check whether inlet manifold union is blowing or sucking!

The turbo union did confuse me since I didn't recall it being connected to anything when it was on the JX and the AAZ definitely had a pipe from the inlet man. to the LDA.

Many thanks for your input. It's making sense now.

[vwooosh...!!!]

Im at the same stage right now, but with an Afn. Im filling her up With oil and turning the key tomorrow. Ive actually put a little 'T' piece in there as you have considered here. So it'll be very intresting to see how or if it 'works' ok..!

[Al Housman]

Just to confirm that the pipe on mine connects the LDA and the inlet hose and has done for a while now. All seems well with it. Hope yours is too.