Captain Obvious

Just because you are getting fuel in the lines that lead to the carbs doesn't mean you are getting fuel INTO the carbs. Before it actually gets into the float bowl in order for the engine to use it, the fuel has to get through the screen filters and past the float valve. You might have something wrong with the filters, a stuck float valve, or a badly mis-adjusted float. I'm making a distinction between TO the carbs and INTO the carbs.

Mike, Your suggestion about simulating the forces of operation is what I had planned to do when I pull the throttle body. I believe you and I are thinking the same thing... That maybe the throttle shaft bushings are worn in some weird way such that the vacuum pulling the throttle plate and shaft towards the engine or the return spring is causing something to bind at times? Zed Head, About that pressure imbalance on the edges of the throttle plate... I was thinking of that too, but I don't know enough to be sure - Does that really happen? If so, it seems like it would plague just about every butterfly valve device out there. I'll double check for crud when I pull it too. I did check for cleanliness while on the car, but you can obviously do a more thorough job off the car. As for the A/C idle up stuff, I had the linkage disconnected right at the throttle body. There was no linkage connected to the throttle shaft at all, and it was still sticky. I can state with 110% certainty that it has nothing to do with any part of the linkage. Guaranteed. So anyone coming up with any theories that could account for the seeming temperature dependence? Thanks for the help guys!!

Well you know the history of this car with the blasting grit and all. My first thought was a return of something related to that. The confusing detail is that the throttle shaft always feels perfectly smooth and free moving when the engine is off. It's only sticky when the engine is running? What causes that??:paranoid: I guess I'm gonna have to pull the throttle body and look at it on the bench.

Thanks for the suggestion, and no, I have not disconnected the BCDD. I know the BCDD is often the cause of what people call a hanging throttle, but in my case, I can't see how it could be related. My problem isn't the BCDD path around the throttle plate... It's the throttle plate itself is not returning to it's stop. There's no mechanical connection between the active parts of the BCDD and the throttle butterfly.

Sometimes when I come to a stop, my idle hangs up and will not return to the correct RPM. Just started like two weeks ago. I know it's got nothing to do with the linkage or the dashpot, because I removed both of them and it was still sticky. I also know that it's not sticky goop inside the throttle body. It's clean. It's not sticky all the time, but when it gets that way, I can feel that the throttle shaft is a little more difficult to turn than "normal". Due to the fact that this is a recent development (now that it has gotten colder), my first thought was that maybe my throttle body was icing up. But heres the thing... I can shut the engine off while the throttle is stuck open a little, and as the engine cranks to a halt, the throttle plate closes just like it should, and moves freely. In other words, the instant the engine stops, it will move free and easy and "clank" hard against it's screw stop just like it should. Two seconds later I can start the motor, and it's fine for a minute or two, and then it gets sticky again. Doesn't seem like ice to me... It's not sticky goop. It's not grit in the bearings. It's not the linkage. It's not the dashpot Anyone have any ideas?

This illustrates perfectly what I meant by it being a second order phenomenon. You aren't controlling vacuum with the mixture, you are controlling idle speed. It's the idle speed that's affecting the vacuum, not the mixture. Vacuum at idle is not an indicator of fuel/air mixture. Peak idle RPM at a constant throttle position is an indicator of mixture. I'm sure we're saying the same thing.

Pics or it never happened.

Haha! Did not. Despite the distain for all things AMC, if it made it this far in that condition, then I think it deserves some applause. I'd rather have a Hornet, but that's just me.

It all seems pretty normal to me... Eight turns down for you = sooty plugs, and smells very rich, good performance? - That's because you are very rich. Three turns down for you = clean plugs, smells normal, good performance? - That's because you have leaned out the mixture to closer to the correct mixture What's the problem? As for highest vacuum at idle, the knobs adjust mixture, not vacuum. I'm no expert, but I'm having a real hard time caring about what the vacuum gauge says when you're messing with the mixture knobs. Any change in vacuum when messing with the knobs is a second order effect caused by a shift in idle RPM. There's no primary link between manifold vacuum and nozzle drop.

Now that's just wrong. Funny, but wrong. :laugh:

Thanks for the details. Wow... That's some beautiful stuff there.

He's talking about the raised center portion of the flange that the wheel studs are pressed through. The raised center portion of the stub axle that protrudes through the hole in the center of the brake drum. He was originally thinking that center portion was a separate piece that might have to come off first before the brake drum could be removed. Now that he's seen pictures, he realizes the center portion is integral to the end of the axle flange. It's all one piece and that center portion does not come off.

Starting at the home page, hit the "Search" button. Scroll down page one and hit "2" at the end of the list to get to the next page. Poke around on page 2 and then hit the back arrow to return to page 1... When I do that, I get this: "Webpage has expired Most likely cause: •The local copy of this webpage is out of date, and the website requires that you download it again. Click on the Refresh button on the toolbar to reload the page. After refreshing, you might need to navigate to the specific webpage again, or re-enter information." I know I could refresh the page, but having to refresh every time I want to back up a page is a pain. Any idea if this a programming issue, or a browser settings issue?

Woof. That's no fun at all. :sick: I almost had to resort to that once, but thankfully I managed to get it off just before that point. I did mangle the shoes and return springs in the process though, but thankfully the drum was OK.

Wow there's some nice stuff there. Are all those cars "real"? I mean, is that a real Dino, a real Spyder, a real GT 40, Even a real Gremlin?

Oh yeah. Something else that can cause a lean condition under high fuel delivery conditions is a clogged fuel filter. Here's to hoping that it was a simple as that!

The only other small piece of info I can provide is that the wheels operate on a mechanical system where it's normal for it to require more torque to move a digit when it rolls from 9 to 0. That's because when it rolls over, it has to move the lowest digit, and every other digit above it that's changing. In other words, it's a lot easier to spin from 0003 to 0004 than it is to spin from 0009 to 0010. It's even harder to spin from 0999 to 1000. Because of that, if there's a damaged piece inside that is jusssst barely working properly, it would be expected that it would fail first when digits are rolling over. So good luck with it, and if it comes to the point where you need another set of eyes inside one, let me know. I've got a speedo here that I can open up if necessary. I might not know what I'm looking for on yours, but at least I could discuss the guts intelligently.

I was into the regular odometer section of mine, but not the trip-o. You wanted ideas though... Everything is gear driven, isn't it? If that's the case, then there's no way it should be able to get stuck without something skipping a tooth or something. Did all the gears look OK to you? Do you hear any clicking? You can spin the input shaft of the speedometer while it's on the bench to make sure everything is working OK. Won't fix it for you, but at least you won't have to go through all the agony of putting it back into the car before learning that it still has a problem. I don't remember if there was enough length sticking out the back, but maybe you could even chuck up your cordless drill on the little stub and use the drill to turn it?

Yeah, that trip odometer cable... :ogre: Barring complications due to a dash cap, pulling the speedo out would be half the job if it weren't for that trip odometer cable. The speedo is pretty much designed to be able to be removed with the dash in the car. In typical Japanese fashion, they set everything up such that it's supposed to be relatively easy to remove the speedo. The electrical cables have significant extra length such that the speedo can be pulled generously far from the dash before you run out of length, and so does the trip odometer cable. Yes, I said it, "and so does the trip odometer cable". The PROBLEM is that they wrapped the trip-o cable around the HVAC ducting so that it didn't hang down on your knee or get tangled up with anything, and because of this, it's tethered too short to get to the screw to release it. My solution was to reach up and unhook the fresh air duct hose above the drivers knees and untangle the trip-o cable from the duct. Once that is done, there is enough length to get the speedo far enough away from the dash to get to the release screw. I think I also pulled to steering wheel just to get more room in there to work. I was pretty frustrated by the time I got the end of that job, so I may be missing some of the details, so YMMV. :bulb:

Ah HA! That's what I thought!! I was starting to think I was losing it! Let me tell you the full story of what I did earlier today... I went to the home page and hit the Search button. Didn't put anything in the drop down boxes. I was presented with 382 results that seemed to be sorted by posting date. I was thinking "Woo Hoo! They did it!! Posted by date is the default". Then I hit the "category" sort button and the were sorted by category (no surprise there), but then I wanted to go back to sort by date, and..... There's no way to do that? Haha! It's a one way street. Not only that, but it stuck. I'm assuming it's in my cookie somewhere because even if I close the browser and start again, it doesn't revert back to the default sort by date. The only time it was sorted by date was the very first time. Isn't software wonderful? As for the featured results being on top, I don't care for it. I'm not sure what the criteria is for "featured", but there's featured stuff in the list from 2006. I find it disconcerting to be scrolling down through a list of items only to have the dates reset halfway down the list. My thoughts on this are unless someone is paying for special attention (featured), then I would skip it alltogether. And if it is a pay service, I would have it time out... You get 30 days of featured top of list for $$. After that, you're in with the rest of the unclean. There's got to be other people besides me who have input into the new site... Here's your chance!! Speak up!! And Mike... THANKS!!!

I poked around the new classifieds today, and I wanted to say thanks for the work being done. I saw the "Recently Added", and that's OK. I'd still rather have a "sort by posting date" button on all the search results. I can't figure out what is the default sort order? If I hit "Search" from the home page without entering anything into any of the filter drop downs... What's the sort order on the results? I get 382 results and I can't figure out how they're sorted... Also, I couldn't find the map. I'm OK with that, but some of the bells and whistles craving members of the forum might be disappointed? :paranoid:

Usually vacuum leaks have much more impact at idle. Your typical vacuum leak is a fixed size hole (or accumulation of multiple holes) which doesn't change with respect to throttle position. That means the amount of air pulled through the leak is a greater percentage of the total air when you are at idle. When you're at WOT, the leak is still contributing air, but it's a smaller percentage of total and hence a smaller impact. However, the L-Jet system, with it's AFM upstream of the throttle body, is a little wrinkle. If the problem is a vacuum leak causing problems at WOT, it's probably something upstream of the throttle body. As Wade mentioned you should inspect the snorkle between the throttle body and the AFM. There might be leaks in other downstream places as well, but they would have more impact at idle than WOT.

Yeah, methinks you're running lean at WOT for some reason. There are lots of things that can cause that, from the TPS adjustment to a bad FPR or fuel pump, etc... Have you downloaded the FSM and the EFI troubleshooting guide yet?

Let me make sure I understand what you're saying... Are you saying that you put your foot to the floor when you are driving around, and it's fine. But you put your foot to the floor when it's sitting in neutral with no load and it backfires and surges? I was thinking the same as Zed... Have you checked that your throttle position switch is doing what it's supposed to? Wade, FYI... no cat in 77 (except CA?), and no O2 sensor in any 280Z. That didn't start until a few years into the ZX.

geezer, I see what you mean about the thread mount. I wasn't aware that the aluminum knob had plastic inserts to adapt to different cars. Here's an idea... Can you move the base portion from your new OEM replacement knob over to your original knob? Does the new OEM have the same center hole as the old OEM? Sounds like a lot of people have plastic bases that have seen better days... Haha! Maybe I should get into the threaded base business? That and AAR's :pirate: