fuel rail and pressure regulator suggestions-78 280Z

[Captain Obvious]

How did you block off the BCDD? You can't just pull it off and slap a flat plate in it's place. That won't work:

[Patcon]

Start plugging ports on the manifold.  Especially the brake booster

[Yarb]

The booster and trans vacuum lines are plugged. (AT is going away after I get this girl running properly). Yes all I did was plate off the bcdd when I removed the egr valve. I assume there are other areas in the throttle body that need addressing. Thanks for your input. I’ve been chasing this for days. Keep going back to what I’ve touched in the past. 

[Captain Obvious]

Yeah, you can't just plate off the BCDD like that. Creates a big leak around the throttle plate and your idle will be sky high.

There are a couple other threads where people had that problem and installed some workarounds. I'll take a quick look and see if I can find something.

[Captain Obvious]

Here's a couple threads that might add some additional explanation:

https://www.classiczcars.com/forums/topic/58760-1977-280z-with-81-83-engine-persistent-2000-2500rpm-high-idle/

https://www.classiczcars.com/forums/topic/56940-79-280zx-fast-idle-2200-rpm/

[Dave WM]

smoke it out.

[Yarb]

Dave, Is there a procedure out there I can follow? I guess it would be a static type test almost like fogging an outboard?

[Dave WM]

I just use a cheap cigar, and a clear plastic tube attached to the brake boost port on the manifold. Then put a stryofoam cup in the TB intake to seal it up. Now stoke up the cigar and start puffing smoke into the manifold. It should resist some the airflow into it. Just keep going and keep your eyes open for smoke leaking out somewhere.

[Yarb]

I’ll try it... Thanks Dave

[Captain Obvious]

About the smoke test... Since the BCDD is simply a bypass around the throttle plate, if that's where your problem is, it won't show up on a smoke test.

Both sides of the throttle plate are in the same "closed system". Does that make sense?

And, I can tell you with 100% certainty that if you just slapped a flat plate on there where the BCDD used to be, you've got a problem. You don't need a smoke test for that.

[Dave WM]

I was thinking he was just chasing a reg vacuum leak. Sometimes on these long threads I just jump in without reading everything. I wonder, do the BCDD fail that often, or is it just folks don't like the way the effects the engine? Mine is hooked up and seems to have somewhat random effects, like between shift rpm, the time it hold open the throttle etc... but it really does not effect my driving since I generally keep the car in gear most of the time, even when decelerating (want to be in the correct gear at all times). Mine will hold the idle up a bit if I coast to a stop in neutral, but its not crazy high, maybe 1500-1800, then it quickly drops as I go below 10mph.

I find the best thing you can do for Z cars is drive them. Seems like some problems are not problems at all with time. I think maybe with out computers and sensors galore, the engines do not react the exact same way all the time, as the mechanical aspects of the various systems are not as repeatable as a working computer controlled modern car. I know my lexus starts and runs exactly the same way regardless of temps etc....

[Yarb]

Thank you for the great information. So, I still have the original valve. The car sat for 12 plus years and before that my father drove it. Ran terribly rich. When I got the car back anything and everything fuel related was in really bad shape. I removed it not knowing capping it up simply doesn’t work. So is there a procedure on capping it correctly or do I put the valve back on and hope it still works? I Appreciate any advice possible. Been chasing this for awhile.