Failed CO emissions - all controls removed - where to start?

[EuroDat]

I'm not sure what the white "Carb" line was meant for either. In all the parrs manuals, they are capped off.

The spare one I have is from a 260Z I believe.

Anyways, if it's capped off it should work fine.

 

[thetwood]

Thanks everyone. I have a charcoal canister on the way. Believe it's the three nipple, but will see when it gets here and dig into how to get it all connected. This info is all great.

Also have found a timing light to use, so hopefully have that soon to test timing. Ordering some new spark plugs as well to do that testing. Progress.

[thetwood]

Okay, thought I'd do something easy and get some new spark plugs. Then started reading and got myself confused. Car currently has NGK BPR5ES. But a lot of what I'm reading shows people going with a 6 (BPR6ES or BPR6ES-11 or even other variants). Is there a preferred spark plug for a 78 280z?

[Dave WM]

5's are a bit hotter, the 6's are the recommended. For testing the 5's will be fine, you just want to see if they change color. Being hotter would tend to burn off deposits a bit faster, but for testing I would think you would be ok, esp for short term test.

fyi, hotter means the insulator is longer, taking more time to dissipate heat to the metal. hotter insulator means less build up. Down side is too hot could lead to detonation (pinging).

Edited November 12, 2019 by Dave WM

[thetwood]

31 minutes ago, Dave WM said:

5's are a bit hotter, the 6's are the recommended. For testing the 5's will be fine, you just want to see if they change color. Being hotter would tend to burn off deposits a bit faster, but for testing I would think you would be ok, esp for short term test.

fyi, hotter means the insulator is longer, taking more time to dissipate heat to the metal. hotter insulator means less build up. Down side is too hot could lead to detonation (pinging).

Thanks Dave. The 5s in it now are super dirty already, so might as well replace with 6s for testing. 

[Dave WM]

oh got it, I did not read completely, yes use the 6's for the reading. Sounds like the 5's were prob put in by PO, to help combat fouling from all the other stuff.

[thetwood]

I now have a carbon/charcoal canister and it looks good. Looking at where it hooks up to, I see where the purge line goes to but the other line shows going to a 3-way connector. I don't have a 3 way connector. I have line directly connecting the dashpot to the bottom of the throttle chamber. Should I just add a 3 way connector in the middle of that? It's difficult to see exactly in the diagrams.

[Zed Head]

7 minutes ago, thetwood said:

 I have line directly connecting the dashpot to the bottom of the throttle chamber. 

Sounds like somebody has messed with your vacuum lines and was unable to resist the urge to connect a vacuum line to the "Sorry:" piece.  Not uncommon.  The dashpot does not use vacuum, it's open to atmosphere.  Make your vacuum lines look like the diagram.  Get a three-way connector.

[thetwood]

10 hours ago, Zed Head said:

Sounds like somebody has messed with your vacuum lines and was unable to resist the urge to connect a vacuum line to the "Sorry:" piece.  Not uncommon.  The dashpot does not use vacuum, it's open to atmosphere.  Make your vacuum lines look like the diagram.  Get a three-way connector.

They messed with almost everything, including the vacuum lines. Sure makes this an adventure. So dashpot does not go to vacuum. In that case, one end of the 3-way goes to the throttle chamber. One to the charcoal canister. What does the third end go to? I think it says to the distributor in the diagram in the EFI manual, but then has a not that it would be for automatic transmissions only. Since this is a manual, does it even need a 3-way? Or does the charcoal canister just go straight to the throttle chamber?

[Zed Head]

1 hour ago, thetwood said:

What does the third end go to? I think it says to the distributor in the diagram in the EFI manual, but then has a not that it would be for automatic transmissions only. 

Yes, it goes to the distributor.  Manuals and automatics both have vacuum advance timing also. The port on the throttle chamber is what they call "ported vacuum".  It only has vacuum when the throttle is open, not at idle.  The distributor's vacuum controlled timing advance and the carbon canister both use ported vacuum.

 

Ported vacuum port on the throttle chamber goes to both the carbon canister and the distributor.

Edited November 15, 2019 by Zed Head

[Captain Obvious]

12 hours ago, thetwood said:

They messed with almost everything

Of course they did. They always do.

To add some info to Zed Head's post... The ported vacuum signal only provides vacuum at a "light cruise" pedal position. There's no vacuum at idle, and the vacuum falls off quickly above light cruise. It's peaky right at one throttle blade position (light cruise), not simply when the throttle is open.

And there are two ported vacuum connections off the bottom of the throttle body. Make sure you are using the correct one. You want the one on the right side. The other one is for the EGR system.

[Zed Head]

Actually, you could describe the vacuum level on the port as matching manifold vacuum once the throttle blade opens.  Zero when it's closed, manifold pressure (vacuum) once the blade moves.  

That's the simplest view.  I think that Bernoulli, and Venturi's, principles have been discussed before as causing higher vacuum at the crack of the blade but I don't think that anyone has actually measured.it.  So, really, it's just none and some.