Charcol canister vac line plumbing in early RX-T .

discopotato03 · Post by **discopotato03** » Fri Mar 13, 2009 10:12 pm

Can anyone with an early (85/86 flap AFM) RX Turbo tell me how the rubber vacum lines go - the ones on the cans purge valve .

I'm pretty sure one goes to one of the throttlebody brass tubes and the other to the inlet manifold downstream of the TB .

Also curious to know what went to the TB's other brass tube .

Cheers A .

steptoe · Post by **steptoe** » Sat Mar 14, 2009 10:21 am

in the flesh or diagram ?

diagramatically the hose connected furthest from the valve is the auxillary purge line - connects to air duct after afm via an orifice restrictor, the next line is tank vapour line think it is part of the fuel rail to get it across engine bay.

The two hoses that are are the purge control valve, the vacuum lineis depicted as being just ABOVE the throttle blade and is also the same source line for dizzy vacuum. There is 2 plastic T pieces at front of TB on this model (and only one on 4 plug computerl dizzy) follow line from dizzy advance and you got it. The main purge line is shown as under throttle plate, again having orifice restrictor nearby. If you find my recent ramblings on this - may help.

page 24 of chapter 2 - 1 emission control system and vacuum fitting

discopotato03 · Post by **discopotato03** » Sun Mar 15, 2009 10:55 am

Thanks heaps steptoe , so the outer most of the big lines goes to the rubber duct downstream of the AFM with an orfice (restrictor) .
The other or middle canister one goes to the fuel tank breather line .

Its the two with the T pieces that I need to get a handle on , particularly if the distributor vac/pressure signal line is plumbed into above (outside) the throttle plate .
ATM mine is plumbed into one of the two barbs leading into the spiders plenum so thats wrong and probably why it feels a bit flat .

Could you possibly scan and post that diagram from your WSM as my manual is 87 and only covers 4 plug engines which as you said are plumbed differently .

Thanks for your time , cheers A .

Gannon · Post by **Gannon** » Sun Mar 15, 2009 12:07 pm

Just for intrests sake, i just had a look at mine (4 plug turbo)

-The big line from the disc shaped thing on top of the canister goes to the intake plenum

-The little line from the disc shaped thing on top of the canister goes to one of the ports on the throttle body above the throttle

-The line from the top of the canister goes directly to the purge line from the fuel tank

The MPFI non turbo 4 plug had 4 pipes going to the canister (as opposed to the 3 on the turbo) and i think one of them was to a purge solenoid.

It appears that the 4 plug turbo just uses vacuum to purge the canister

discopotato03 · Post by **discopotato03** » Sun Mar 15, 2009 12:17 pm

Thanks Suparu , the combination I need to know is Aust 85/86 MPFI Turbo because I am trying to make 4 plug system (Spider Turbo) hardware work on a 3 plug RX Turbos purge and distributor vac plumbing .

I think the essential difference is no purge solenoid valve on the 3P system and no dizzy vac because timing is computer controlled .
I think the 3P system has restrictors that the 4P system didn't because the purge solenoid had it internally .
Also there could be a bullet shaped restrictor that screws into the side of the Spider plenum , must nut it out as well .

Silly me didn't draw myself a diagram and the people with the 86 L factory WSM are not open ATM .

Cheers A .

discopotato03 · Post by **discopotato03** » Sun Mar 15, 2009 9:51 pm

On top of it now I think .

I dug out the std L MPFI-T inlet manifold and luckily it was pretty much intact plumbing wise .

First I looked at a spare 3 plug era TB to check out the drillings from the two brass vac Tubes . The NS one lines up with the throttle plate and the OS one is upstream of it .

I also wanted to trace the forrest of steel/rubber tubes to see where the dizzy got it's vac/pressure source from .
I traced the small steel tube from the NS end of the rails through to a plastic "T" piece which gets is vac/pressure from the NS TB tube . The other side of this T goes to the smallest sized hose at the charcol canister .

There are actually two plastic T pieces the above mentioned one is the lower NS one and the 2nd is the upper OS one .
The 2nd one connects the EGR valve to the OS TB tube and the EGR Solenoid valve .

With a bit of creative work with vac hoses I now have the dizzy correctly plumbed and as far as I can tell the charcol canister as well .
I also got around to setting the idle speed to ~ 750 and checked the ignition timing . It was floating around 21 deg and I set it to I think 24 which is the end of the flywheels scale . It really likes this and there is no hint of detonation .

I would have refitted the 76/170 thermostat only I forgot its the thermostat not the gasket thats the same as Datsun 2 bolt 200B . Armed with an EA82 gasket tomorrow the prefered thermostat goes back in .

Cheers A

steptoe · Post by **steptoe** » Mon Mar 16, 2009 8:32 am

Yep, reads correct to my recollection.

The more you look at the fuel and vacuum rails the better you get at working them all out. My first thought was to get my Humbrol paints out and colour code the different lines

discopotato03 · Post by **discopotato03** » Mon Mar 16, 2009 6:59 pm

Well it seems to be running better now though I am concerned that the fuel tank pressurises to the degree it does . I just hope that boost pressure is not the culprit .

I put the 77/170 deg thermostat in today and vowed never to buy the gasket off Repco again . The Dayco one they sell has slots instead of holes and even then the inner parts are not close enough . You shouldn't have to cut one side off (open ended slot) and decrease the inner ends to get the bolts back in .
Anyway it's sealed up with Permatex No 3 which doesn't set hard .

Cheers A .