Hi guys. I'll start out by saying that, yes, I've looked in both the Haynes manual and the FSM and have been unable to find a specific name or function for the part I'm questioning. Perhaps I'm blind, and if that's the case, I sincerely apologize...

Okay, so directly below the auxilliary air valve there is the part that I'm questioning. There are two hoses going to it which appear to carry coolant (I'm assuming this is to give the AAV an accurate read on engine temp. Then, on the firewall side of the piece are three thin hard lines coming out. On my car, one is already capped, the other two lead to the bottom of the throttle body. These look to be air lines, vs. coolant lines. Can anybody tell me what this part is called and exactly what it's function in? This is in a race car so I'm trying to pull whatever is NOT necessary. I think I will keep the AAV in place as sometimes cold starts will be an issue, just not sure how key this secondary piece below the AAV is to it functioning well. Would like to toss the part and all the extraneous hoses/lines if it won't be hugely detrimental. Thanks again.

 

I have all of that removed including the aux air valve and cold start injector and I don't have any trouble starting in the morning (woke up to snow this morning). I have to keep it at a high idle for a minute or two but no big deal. do a search for intake manifold clean up for the 280zx. There's a thread that what you can get rid of.

 

Thanks, thats encouraging. I've seen the thread you are referring to, but I don't believe it discusses what this specific it is. Just want to know what it is I'm pulling.

 

Always state the year of your car...

I have no idea what you mean by "firewall side", but the part you are referencing (pics would help), sounds like the Thermal Vacuum Valve. Look it up in the EF & EM - Exhaust Emission Control System section of the FSM.

 

Thanks NismoPick. Alright, now we are getting somewhere. The part is apparently the Thermal Vacuum Valve (sometimes called the Ported Vacuum Valve?) Mine has three lines coming out of it, two the TB which are still intact, and a third which is plugged, but perhaps used to go to the Thermo Time Switch. Oh, and the car is a 1980 CA car. What I meant by "firewall side" is toward the rear of the car. I've already pulled the BPT valve as this I understand was to control idle when running the AC (which is long gone.) Now trying to figure out if I can pull the TVV. I will be leaving the EGR valve in place, although the car will never again face smog checks or anything like this. Again, just trying to get rid of whatever stuff in the engine bay I can. Thoughts? Thanks again for your patience as I'm learning.

 

Picture?

 

Here's the part I'm referring to, it is mounted directly underneath the auxilliary air valve. You can see the three small hard lines coming out of it on the far side, and one of two small coolant hoses that lead to it on the front side.

 

Yep... you can get rid of it as long as you cap the other ends at the throttle body. Also, where is your distributor getting it's vacuum advance signal?

 

dizzy doesnt vac advance anyways. its curved so well from nissan that its only for granny driving.

 

NismoPick, I'm glad you asked that question as honestly I'd not looked at the vacuum advance. However, since you asked, I looked this evening and see that there is currently no vacuum line running to the vacuum controller, the port has just been left open. I've not had a chance to fire up the car in the last couple of days so I'll see what happens if I plug it. I just recently set the timing at 15 degrees advanced at 700rpm (intentionally more advance than stock) but am curious to see what will happen if I cap the vacuum line. Where "should" I be pulling vacuum from? Again, considering this is a race car (generous use of the term in Lemons) do I really need the vacuum advance as the car doesn't get any "around town" driving at all, it's either warming up or driving as fast as we can get it to go

 

I'm continuing to clean up the intake area and all of the various vacuum lines (some of which have been removed by the PO.) As yet, I've been unable to find a complete diagram of all the vacuum lines, similar to a wiring diagram I suppose. As such, I've got a couple of areas of confusion. First, there are three vacuum lines which lead into the Thermo Time Switch. These lines then go down to a three pronged bypass, and on mine, two of the three lines were already not in use (show here with blue caps on them.) Is the TTS even functioning properly with only one of the three ports active?? I'm tempted just to yank it, but need to understand better if removing it will leave the cold start valve overly active, or if it will completely disable it.

Secondly, I have no vacuum line running from the distributor to the TB, the port on the distributor is just sitting open right now, so presumably the vacuum advance is not working. I know this needs to hook up to the TB, but there are SO MANY non currently used ports on my TB I don't know which one I should be hooking it up to. Does it even matter, or will they all function identically?

Thanks in advance.

 

Merged threads... no need to make a new thread for every "What's this?!" question.

Maybe it's been too long since I've worked on an N/A, but there shouldn't be any vacuum lines going to the thermotime switch... You are talking about the two prong sensor in the thermostat housing? Pics?

And I'm looking at tons of vacuum diagrams right in front of me in my hard copy FSM... EF & EC "Evaporative Emission Control System".

 

Thanks NismoPick. As you may well have figured out, I'm new to this generation of cars, so my apologies for my ignorance. It appears that I was incorrect in the naming of the part I'm referring to, it is in fact that Thermal Valve Vacuum directly below the thermostat housing that I'm working with. And, now that I've got the correct name, I've been able to find some images in the FSM that match what I'm seeing (I have the D2 Type, and then D1 Type from on top of the manifold has already been removed.) So, here's my question: Only one of the three lines coming from the D2 TVV is not plugged, and it's running into the triple nipple vacuum collector pictured in my previous post. This vacuum line runs directly to the bottom of the TB, NOT the vacuum collector on the side of the Distributor that the FSM shows with a secondary lead going to the now-gone D1 type on the manifold. To see what would happen, I moved this line over to the vacuum collector on the Distributor (which has just been sitting open for as long as I've known the car) and it raised the idle way up, probably by 600rpm or so.

Given that these two TVV's appear to be linked originally, and one is already removed, and that two of the lines leading to my remaining one are capped, my inclination is just to do away with it altogether as it's hard to imagine it is still performing its designed task. If I understand correctly, this system is most active while the engine is cold and at lower rpms, something this car just about never experiences. Do you see any reason why I can't just remove this entire system? And, if I do, should I simply cap the line on the bottom of the TB that the TVV lead is currently leading to? Secondly, do you have an illustration as to which nipple on the TB should connect a vacuum line to the vacuum collector on the distributor?

Thanks again for your patience, I'll get there!!