Leaderboard

The big hose is T'ed with the idle speed control air bypass. So a simple plug at the end of the hose or at the mechanism itself should work . Looks like the bypass feeds directly in to the intake manifold. Follow the air flow path from one side of the TB, through the screw controlled idle controller, and to the intake manifold to be sure. You need to be aware though, that removing the BCDD will bring back the original problem it was meant to fix. You'll have a gassy smelling car if you coast to a stop while in gear. You might end up wishing you had fixed it. The 81-83 ZX's have a mass of vacuum controlled devices that can leak. Here's another. Which brings up another reason for idle speed to increase - ignition timing. You might have a sticky vacuum advance mechanism n your distributor. Pretty common. There are are also thermally controlled vacuum valves placed around the engine. Can't remember how many.

Yup, I think some (or most) of the high idle issue is due to the BCDD blockoff method. I've never messed with the ZX under the manifold style, but as Zed Head mentioned, you might be able to take off that last other plate that's under there and then maybe use a simple plate to block off the holes. I don't know what (if anything) else that remaining slab does, but you would definitely have to cap the hose connections that go to it if you removed it. That option doesn't exist on the earlier design with the BCDD on the underside of the throttle body. There's no way to ever use just a simple plate because the vacuum ports and valve seats are integral to the throttle body casting itself. You might have a simpler option with the later version you have. Good luck. And here's to hoping solving the problem is as easy as it seems at this point!

I just watched this and it has some good info on different things on the throttle body. Your dashpot plunger might be holding the throttle at a high RPM, I forgot about that thing. It's for manual transmission cars only and keeps the throttle from dropping too much between shifts. Mine works good after I adjusted it but I don't remember how I did that. The hole I was thinking about that is associated with the BCDD is the vacuum advance. The video shows the slit in the throat of the throttle body but also shows how he connected the vacuum advance to another ported source for timing advance. Here are those tech tips that have helped so many of us, especially me cause I'ma sorta stupid. If you'll click on the EFI and FUEL section there's the gold mine. http://atlanticz.ca/zclub/techtips/ I'm asking you to click on a link now! Trust me though, this is a good one. Cliff

Sure thing! Uploading images elsewhere is just a habit I've grown used to, but I'll start attaching the images from now on. I'll definitely give that thread a read, thank you!

When you're bored as hell this thread has some pertinent info for your car, I think. http://www.classiczcars.com/topic/50850-no-vacuum-at-throttle-body-ports/

It's not that simple. You can't just remove the guts and slap on a simple plate. When you remove the guts, you remove the valve that seals one side to the other. I whipped this up to hopefully illustrate the issue:

New product!! The marketing dept. sees Lightweight Fiberglass Replacement Floor Pans!! You've got the mold, right??

I suspect you didn't block off the BCDD correctly. As siteunseen alluded to above, it's not as simple as removing it and slapping a flat plate in it's place. I've not looked into the details, but I suspect the later ones under the manifold are pretty much the same concept as the earlier ones on the bottom of the throttle body. Do you have any pics of what you did there?

You can check for the stuck throttle blade by pulling up on the pedal with your foot or manipulating it by hand under the hood. There are two return springs, one on the TB itself and the other attached to the linkage. On the ZX engines I think that the linkage spring is very visible, right on top. I snipped ypur picture and drew an arrow to the spring and linkage, Make sure it's free and working right. Also arrowed the ZX idle adjustment screw. It works by letting a small amount of air past the throttle blade. If you figure out the excess air problem you'll still have the goofy ECU problem. That could be a loose connection or a bad ECU. Is it a ZX ECU or the original Z ECU? They're different. Should be next to your left foot, behind a panel. With a sticker on it that ID's it. Take a picture of the sticker. It's probably the Z ECU and they are known for failing like yours is, with the tapping it rich/lean problem.

I have a set of 14” Western wheels that I need to get rid of. They are free to pickup. I am in the Burbank, CA area. Update: Wheels are gone.

There is a thread here from Wheee! where he shows details of how he did the prep and welding of his weld on - coil overs. 1976 280z Restoration Progress is the name of the thread, page 63 is where it starts. I highly recommend this type of installation and coil over style. Any welding shop can do it. There is nothing special about welding one steel tube to another. This is not a plug, well not much of one, but I bought Gecko weld on coil overs for my 510 and I'm pleased with the quality and price. They are new and trying to make a good impression. A full set of 510 coil overs were something like $850 USD shipped. They had a similar deal for S30.

Hello again gentleman, so I bought a 72 with a seized engine. I've read it's fairly common from car siting for 10+ years. I've read about the mystery oil and ATF, coke and even read about towing the car and popping the clutch to free up engine. I just received the car last Friday and What I'm trying first is mystery oil soak. It's been 4 days and nothing. I'm thinking about pouring some HOT ATF and trying that. Has anyone had success on freeing up a seized engine? Also, I need ideas for trying to turn the crank pulley instead of just the bolt, I'm worried it will break. Maybe even taking starter out and try turning the flywheel with a pry bar. What do you guys think? Greatly appreciate your time guys