B3 AAZ tech info

[Big Daddy Roth]

I have a 1993 B3 AAZ (Canadian Model). I'm having trouble finding any tech info. I particularly need wiring schematics and info on how the EGR system and boost control works.

For example: Isn't that boost line supposed to go to the pump somewhere??



Pics of pump





Anyways, It's not the typical mk3 AAZ, something is completely different here.

[gldgti]

looks like the LDA top is a blank plate from your photo's - normally there'd be a barbed fitting for the boost line to go to - not that it does anything really on the aaz pump with the stock pin in there.

the EGR valve (on the backside of the inlet elbow) opens and reacirculated the exhaust into the inlet at certain times. its best to remove that junk and blank off the exhaust manifold and the hole on hte elbow, since hte EGR doesnt do much good for the emissions and really just gums up the intake anyway. best rid of it.

boost control is just the turbo wastegate, it probably has 2 lines going to the actuator - one is vacuum and goes to the backside of the diaphragm, opens the wastegate when the microswitch on the throttle lever is closed, or otherwise below 3000rpm. above 300 rpm or when the microswitch is open on the thottle lever (large throttle input) the wastegate is shut and the turbo will boost properly.

you may remove the protective plate on top of the throttle lever assy and you can see the microswitch. it is adjustable for position, you can make it come on at loer throttle inputs, this works well.

if you want more boost, put a T into the boost line from the compressor housing to the wastgate actuator, and bleed off some air. with an open T on there with hte garrett t2 or ko3 you'll make about 22psi :-)

[Vincent Waldon]

Yuppers... standard Canadian Passat eco AAZ... no boost enrichment, throttle-switch actuated part-time turbo and EGR.

Unfortunately there's no LDA mechanism or drillings under that cap... so the only way to add boost enrichement is to swap out the top half of the pump.

You can delete the EGR and throttle switch and simply run the turbo full time by leaving the vacuum line on the wastegate open to atmosphere.

[Henchman]

Nothing I can add here!  Exact same as mine, even the cap on the intake barb was the same!

Ian

[Rabbit on Roids]

looks like the LDA top is a blank plate from your photo's - normally there'd be a barbed fitting for the boost line to go to - not that it does anything really on the aaz pump with the stock pin in there.

the EGR valve (on the backside of the inlet elbow) opens and reacirculated the exhaust into the inlet at certain times. its best to remove that junk and blank off the exhaust manifold and the hole on hte elbow, since hte EGR doesnt do much good for the emissions and really just gums up the intake anyway. best rid of it.

boost control is just the turbo wastegate, it probably has 2 lines going to the actuator - one is vacuum and goes to the backside of the diaphragm, opens the wastegate when the microswitch on the throttle lever is closed, or otherwise below 3000rpm. above 300 rpm or when the microswitch is open on the thottle lever (large throttle input) the wastegate is shut and the turbo will boost properly.

you may remove the protective plate on top of the throttle lever assy and you can see the microswitch. it is adjustable for position, you can make it come on at loer throttle inputs, this works well.

if you want more boost, put a T into the boost line from the compressor housing to the wastgate actuator, and bleed off some air. with an open T on there with hte garrett t2 or ko3 you'll make about 22psi :-)

same thing as un hooking the line from the wastegate. the wastegates pop open at 22 psi anyway. so a T isnt doing anything, besides leaking boost. if you just un hooked the boost signal to the wastegate, you would be doing essentially the same thing, but without the boost leak.

[Big Daddy Roth]

Thxs guys,

BTW, I'm not up to speed on my diesel tech yet, so what's an LDA?

Is there a publication or a tech reference for the B3 AAZ? My Passat Bentley doesn't cover the diesel.

[commuter boy]

You got the neutered "Umwelt" Passat AAZ.

Probably a K14 turbo (which I suspect is different than the other K14's that some come with), an EGR (which most people blank off to keep soot out of the engine), the shorter, single stage 1.6l injectors instead of taller dual stage 1.9 ones, and the blanked off turbo line hose with no connection to the LDA that you noted.

The LDA is on most other AAZ pumps, it has a line from the turbo to it that increases fuel delivery to match boost.  Yours doesn't have it, and therefore burns a lot cleaner than most AAZ's since the turbo adds more air but less fuel. 

I had Giles rebuild my pump to put an LDA on it, but I always got crappy mileage on it for an AAZ Passat even with new nozzles in rebuilt injectors and a 2.5" downpipe and straight back exhaust.  I wasn't sad to send it to the junkyard.

[burn_your_money]

Yours doesn't have it, and therefore burns a lot cleaner than most AAZ's since the turbo adds more air but less fuel. 

I think the lack of a LDA increases the NOx emmisions. Maybe someone can confirm this?

The "LDA" is basically the top half of a turbo pump. It has a boost compensator in it. You have a fake one. It looks real but is lacking the machining and "guts" on the inside.

[gldgti]

looks like the LDA top is a blank plate from your photo's - normally there'd be a barbed fitting for the boost line to go to - not that it does anything really on the aaz pump with the stock pin in there.

the EGR valve (on the backside of the inlet elbow) opens and reacirculated the exhaust into the inlet at certain times. its best to remove that junk and blank off the exhaust manifold and the hole on hte elbow, since hte EGR doesnt do much good for the emissions and really just gums up the intake anyway. best rid of it.

boost control is just the turbo wastegate, it probably has 2 lines going to the actuator - one is vacuum and goes to the backside of the diaphragm, opens the wastegate when the microswitch on the throttle lever is closed, or otherwise below 3000rpm. above 300 rpm or when the microswitch is open on the thottle lever (large throttle input) the wastegate is shut and the turbo will boost properly.

you may remove the protective plate on top of the throttle lever assy and you can see the microswitch. it is adjustable for position, you can make it come on at loer throttle inputs, this works well.

if you want more boost, put a T into the boost line from the compressor housing to the wastgate actuator, and bleed off some air. with an open T on there with hte garrett t2 or ko3 you'll make about 22psi :-)

same thing as un hooking the line from the wastegate. the wastegates pop open at 22 psi anyway. so a T isnt doing anything, besides leaking boost. if you just un hooked the boost signal to the wastegate, you would be doing essentially the same thing, but without the boost leak.

If i just unhooked the boost like entirely, i could make well above 22psi back when i still had the t2 on the engine. i saw it go past 25 psi quite a few times.... however, my T3 one seems to open at about  23psi all by itself.

[Big Daddy Roth]

This is so confusing. I only have one line going to the wastegate actuator. It's the main one from the compressor.

I don't see how the wastegate is controled by the limit switch.

I'm gonna post up more pics.

[Big Daddy Roth]

ok, I did some looking around my engine bay and found the following:

This vacuum actuator


...which pulls on this


I have no idea what that does.

But it looks like it's controlled by these things (located beside the batery, in front of the cruise pump)



I have a feeling the switch on the throttle controls the one vacuum solenoid.

And here is some other missing stuff. Isn't there supposed to be a line from that thing on the bottom of the air box to the broken port on the side of the airbox? What is it for?



And the other line that goes to the air box, goes to this:

which I think controles the EGR valve.

This is the water manifold on the front of the head. I know the black sensor is for the temp gauge and something else (it's got 4 wires). But I have no idea what the brown one is for.


Then there is this thing in the line from the breather


Outside Air Temp. What for? I don't have MFA


As you can see, this is why I would love to find some sort of Bentley info for my car. Electrical schematics would be nice.

[Vincent Waldon]

OK:

1) The solenoid-controlled vaccum actuator on your pump is for fast idle when the engine is cold or when the A/C is on. Controlled by the ECM.  The switch on the throttle is one of the things the ECM uses to determine if fast idle is required, as far as I know.

2) The air filter housing looks like it *had* cold air preheat... the big corrugated tube at the bottom of the picture goes to a tin shroud over the exhaust manifold.  A vacuum-actuated flap inside the air filter housing(which is what the hoses are for) gives the engine warm air under cold conditions.  I've actually never seen one on a diesel... that and the MFA are making me wonder if your car was once a gasser.

3) Brown temp sensor is often the A/C cutout...it shuts off the A/C if the engine is beginning to overheat.

4) Thingie on the breather hose is a small heater to keep ice from forming in the PCV circuit. 

[Big Daddy Roth]

Holy ***! I have an ECM?

[Vincent Waldon]

It's a module, not a computer... so just a bunch of logic circuits... #136 near the top of your relay plate (if Passats are like MK3s):



(guy on the left.  Guy on the right is the actual glow plug relay, which also takes its orders from the ECM)

[Big Daddy Roth]

and my B3 is an original AAZ. Not a transplant.