1977 280z EFI Nightmare

[ckurtz2]

Time to reboot this thread again @Captain Obvious

I got the freeze plug at the back of the block where it was leaking replaced, a new 5speed, clutch and all those fun things with it installed as well. Now back to the engine demons. All I have left is to try and fix all those vacuum issues I had, and fix up some new alternator wiring for an 80amp one I got before I try to fire it up again.

The more and more I started looking closely at how my vacuum lines are set up the more disappointed at myself I have become. I had ran the vacuum from the front facing point on the throttle body straight to the distributor. I also had run a vacuum line from the one that faced back on the throttle body straight to the carbon canister. Not to mention the line was to big and pretty much floated on the ports. So ummm yah, disappointed in myself regarding that. Plugging the rear one, and then fixing the forward facing one to a T running to the canister and vac advance should fix that like you mentioned. Just waiting on 4mm vacuum line because my local auto stores did not have them. 🙂

I also noticed that the large vacuum hose for the air regulator did not have any clamps and was actually pretty loose which also I am sure added to my vacuum problem. Just fixed that today.

And the icing on the cake was thermal vacuum valve. I have the coolant lines properly set up on it. However, I capped one of the vacuum ports and sent the other straight to where an AC vacuum line is supposed to be (and it was also loosely fitted). I also have no AC. So my question is, Should I completely remove the thermal vacuum valve, or should I just plug the vacuum ports for it? What exactly is its function? I deleted EGR and BPT. 

 

[Captain Obvious]

Yup. Details are important and all that kind of stuff is killer on the system. And don't beat yourself up. The good part is you're finding stuff that needs to be addressed. happens to everybody!

The mixed up nipples on the throttle body probably wasn't causing a big issue, but if the lines on the air regulator are leaking, that could be a big deal since some of those lines are on the high vacuum side.

I believe the only function for the TVV is to enable or disable the EGR system in response to engine temperature. When the engine is cold, they disable the EGR system so it doesn't make an already struggling idle worse. And then once the engine warms up and the idle is strong and stable, they allow the EGR system to operate. If you have deleted the EGR, I don't think the TVV has any purpose anymore.

However, about removing the TVV completely... The TVV screws into a heating plate that also warms the idle air regulator, and even if you aren't using the EGR system anymore, the heating plate still adds value to the AAR. So you can cap off the TVV stuff, but probably don't want to take it (and the heating plate) out completely.

[ckurtz2]

@Captain Obvious

Thank you so much! I will just cap both of the vacuum ports then and leave it on. Hopefully by this upcoming weekend I will have everything corrected and together. If it still runs like trash I will go straight to a compression check and get back with numbers. And then the real fun will begin. Lets hope it doesn't come to that haha. 

[Captain Obvious]

Good luck with it, and let us know how it goes. One fix at a time!

[ckurtz2]

Thanks! Got the TVV vacuum ports capped.

Next thing I noticed is that I have no gasket between where the air regulator goes into the intake manifold/throttle body. Is there supposed to be one? The place I am talking about is in the photos below.

 

Edited April 27, 2021 by ckurtz2

[S30Driver]

Yes, hard to see though until you remove the 90 degree hose fitting.   Looks similar to the one for the cold start valve.

[Captain Obvious]

What he said. And that gasket is definitely a very important one because it's on the high vacuum side.

Same thing with the cold start valve. If they didn't put a gasket on the AAR connection, maybe they didn't put one on the cold start either?

I'd use a tiny bit of RTV on those gaskets. Some details about that here:
https://www.classiczcars.com/forums/topic/65119-tuning-with-an-airfuel-gauge/?page=2&tab=comments#comment-617333

 

[ckurtz2]

Just pulled it off to double check. Behold... no gasket 🙃  I am amazed the car even ran haha. With all these leaks adding up it had to of had literally zero vacuum.

Looking online I could not find a gasket for the AAR, only for the CSV. I did see there was a gasket for the CSV luckily. Does anyone know where to get the AAR gasket from? Only place I could find it was on MSA and it was unavailable. 

Edited April 27, 2021 by ckurtz2

[Mark Maras]

I've used a cereal boxes, scissors and a hole punch for paper to make gaskets similar to that. I coat the gasket with a bit of oil and assemble. I've never had one fail.

[Patcon]

They also sell cut a gasket material at most parts stores

[siteunseen]

1 hour ago, Mark Maras said:

I've used a cereal boxes, scissors and a hole punch for paper to make gaskets similar to that. I coat the gasket with a bit of oil and assemble. I've never had one fail.

You're who I learned that from!

Take that elbow off and lay it on whatever you choose and lightly tap an impression on the material. Cut it out with an exacto knife and a hole punch. 

[Mark Maras]

 Or lightly coat the part with grease, press it onto the gasket material and cut off the unstained parts.