Captain Obvious

I wish I could add some Weber specific input along with Blue, but the only thing I know about Webers is that they're carbs... I've got some Mikuni (motorcycle) experience, and they've got similar "progression" holes. The only thing I could add that might be applicable is that the more closed you can get the plates at idle, the better. A lot of the problems I see people having with the bikes idle is that they're not truly running on the idle circuit. The bike is running so crappy that the only way they can GET it to idle is to crank the TV open and expose the holes. And I've been surprised on just how closed you should be able to get the plates for idle. This applies to the z car carbs as well.

Probably never showed them here. Basically I modified a set of round tops so I could drop them "plug-n-play" into my 260 without messing with external return springs, linkage changes, or different heat shield arrangements. Here's a couple pics. The whole story is over at zcar.com. - ZCAR.COM - Round Tops Customized Drop-In Replacement For 260

Cool. Was a shot in the dark just hoping it might ring a bell. I had a hard time convincing myself that vacuum had anything to do with it. I kept telling myself that the vacuum force on the butterfly should be balanced. As much force should be pulling on the top trying to open it as pulling on the bottom trying to close it. So I started looking for some other non-balanced phenomenon and ended up with the gummy steel to gummy steel theory. It's still a theory, but one that I have experimented with a little using a shop vac and blue marking dye. I can pull just enough of a vacuum with the shop vac to get it to show up a little on the bench. So, I would be a little disappointed if you've got enough wear to cause this kind of issue after just 2000 miles though. Makes me think it should be something else. Did you ever see my round tops with the integral return springs on the shafts? Did I ever show them here?

Let's hope that you did in fact find the root problem. Do you have any pics of the stuff you found when you unwrapped the FI harness?

I would not add any grounding wire to the EFI system without very careful consideration. Pardon the geek based thread jack... the ECU is a precision analog system which does some of it's signal processing at very low levels and Bosch (who I assume was pulling the strings at Hitachi) paid careful attention to where the ground currents are flowing. When you're acting on analog signals, current through any resistance (including resistances to "ground") cause voltages to occur where they might not be wanted and this can cause errors in the system. For example... They were very careful to segregate the injector current from all of the other currents flowing through the system. They were also careful to create their own ground connection for the AFM and air temp sensor. On paper, all of the grounds are connected together. And with an ohmmeter, that truth can be verified. But... just because they show as connected, and measure as connected, doesn't always tell the whole story. You don't want the headlight current flowing through the same ground that the temperature sensor uses...

Haha! Excellent! So in light of the additional info, I believe that those ring terminal grounds do NOT come from the EFI harness and I stand by my original claims: How do I know? Why do I care? Because my PO messed with the electrical system on my car, and I've spent some time trying to piece it back to the way it should be. And this thread is helping me a bunch because I've long known that he messed with the wiring up around the coil and AFM. Not quite sure yet exactly all of what he did, but I know it's not right. My car currently does NOT have a ground strap on the AFM, but I've got this misplaced ring lug groung coming off on one of the timing cover mounting bolts? I also have a completely unused foot long piece of wire with empty ring terminals on both ends (obviously is supposed to be a ground somewhere). I don't know where this stuff is supposed to go, but this thread is helping. So, keep discussing!! Please! And mgood... I third the comments about the beautiful engine compartment!!

Don't know if it's applicable or not, but I just went through something very similar with the butterfly on my FI throttle body. No linkage connected, blip the throttle, and doesn't always return to idle. Worse if you hold it above idle and then release it slowly (instead of a "blip"). Most interesting thing about mine was that it only did it when there was engine vacuum present. With the engine not running, it always snapped hard clean back to the adjustment screw stop. I think I have tracked mine down to worn through hard chrome plating on the throttle shaft which has exposed the gummy soft steel underneath. This soft steel of the shaft does not slide well against to the soft steel of the sleeve bushing pressed into the throttle body. I believe this soft steel to soft steel contact only occurs when engine vacuum pulls the butterfly towards the intake manifold and that's why it doesn't do it with the engine off. In the end, I wrapped my return spring another wind around the shaft and called it a day. Doesn't fix the problem, but seems to fix the symptom. If it gives me any more trouble, I'm going to mount hardened bearing surfaces on the shaft and maybe swap out the soft steel bushings for acetal. Anyway... Way too much about me... So does yours only stick while the engine is running, or is it at all times?

Actually... looking at the photos again, I want to enter an appeal... In mgoods photos, there are what appears to be TWO wiring harnesses going under that cable clamp near the AAR. There is a large diameter harness (which is clearly the EFI harness), and there's a small (1/2 inch) harness laying on top of it. That ground ring terminal connection actually comes out of the SMALL harness, not the EFI harness. So where does that other harness go? Does it actually tie into the large EFI harness somewhere out of frame, or is it in fact part of the engine bay harness and NOT the EFI harness. And what about the one at the AFM? Does that ring terminal actually emanate from the EFI harness, or does it come out of the bay harness? Huh? Huh? I'll take my lumps, but I want to double check first!

Haha! Me wrong? Completely plausible. Probable even! mgood's photos clearly show ring terminal grounds. :embarrass: I believe I have generalized and incorrectly assumed similarities between years. Please forgive me... Here's some input for my defense: 1) That ring terminal connection to ground near the AAR is not shown on the 76 wiring diagram. 2) That ring terminal connection to the AFM is not shown on the wiring diagram either. 3) I've got a 77 and I have verified that neither of those ring terminals exist on the 77 wiring harness. 4) My statement about ground connections holds true for 77. Unfortunately we weren't talking about 77! Do I get special dispensation since even though I spoke incorrectly due to my over generalization between years, I did nail the root cause of the problem!

I don't believe there are any "chassis" earth connections in the FI harness. I think the only connection to ground is that big wire which connects directly to the battery. From that connection, it splits within the harness to branch out to "provide a ground connection" to a bunch of locations within the system, but that sole connection to the battery is the ground for the whole system. There are no ring lugs coming out of the EFI harness, and the metal ECU case is not electrically connected to the circuit. Basically, if you have a problem with that main ground connection to the battery, there is no other backup which can share the load. And unless I'm missing something (which is completely possible!), the car will not run. That said, it's absolutely clear that you've got some kind of intermittent connection issue, but I don't think it's a grounding problem. The thermotime switch should be completely out of the picture unless the engine is cranking, so I wouldn't worry about that. Same goes for the CSV. Once the engine is running, the CSV is doing absolutely nothing. The AAR changes too slowly to react as you described. Even if you would disconnect it completely, you wouldn't see any effect for fifteen seconds or so. That leaves the temp sensor... If you have a shaky connection to the water temp sensor it will cause exactly what you're describing. Basically, if you open circuit the temp sensor, the ECU interprets that as an extremely cold engine and dumps in lots of extra fuel to account for the low temperature. If, by wiggling the wires, you are breaking the WTS connection, the engine will stall because you're flooding it.

Well I got a pretty good idea what you're going to be doing tomorrow. Don't tease Murphy... :laugh:

If the cap is free floating and isn't glued down, taking it out isn't bad at all. I don't remember if it's necessary, but taking the steering wheel off first makes it easier. A warm day helps too. If it's glued down, you're on your own.

I'm not sure if this is a typo or not, but you've said it twice now... You're happy with 5-10 minutes of clock error per DAY? To each his own, but I would not be happy with that. I'm thinking you meant per week, or month?

Yes, in theory, if you never loosened up either of the tie rod ends, then the alignment should not have been affected. Steering wheel position could shift, but basic alignment should still hold. That said, if I replaced my bushings, I would not be surprised at all to find I changed the alignment some. "Shouldn't" change, but...

Oh, and Yes... There are some high impedance points in the ECU design... Like MegOhms high. So it's perfectly conceivable that dust and/or other contaminants which have accumulated in these areas over the years could slightly affect operation. :bulb:

As a matter of fact, way back when at the factory, they probably were cleaned with water or alcohol after soldering. Back then? Probably alcohol. Just make sure they're thoroughly dry after cleaning before you put power on anything. (And I would not recommend compressed air to speed the drying process...)

Haha! Bring it on! That would be excellent.

I've thought the exact same thing. I suspect that if you take it off there and put it back on there you run the risk of changing the door alignment. But, if you take it off at the "normal" location, I can guarantee that you'll mess with the door alignment. So, I'm hoping someone has the answer...

*Cough* *Cough* Why limit yourself? *Cough* LM317 *Cough* *Cough*

I know you have said it's not a fuel issue, but I'm having trouble coming up with any situation that would be strictly confined to just the front three cylinders. Everything else would be common to all six cyls. Humor us? Try what FastWoman suggested:

What carbs do you have on the car? The original flat tops, or has it been converted to round tops? Also, how did you ensure that the carb(s) were getting fuel?

There should be one plastic washer on each carb, and best as I can tell, that washer exists simply to prevent metal to metal contact when and if the piston rises all the way to the very top. When the piston reaches end of travel in the upwards direction, that's where contact is made. About the sizes... I don't think the thickness is that critical. If you've got one in the other carb, can't you just measure the thickness of that one?

Right... I was just talking about the temperature of the air that was exiting, not the location of the exiting air. It is normal for the air that comes out of the dash and center vent to be unheated. However, it may not be normal for there to be air coming out of the dash and center vent at all. That depends on the position of the slider on heater controls.

Stuff like that burns me up. Sometimes you buy stuff and everyone knows it's a "kit", and part of the fun is the finish work. But I'm assuming those manifolds aren't marketed like that... Anyway, it sounds like the changing of the mounting hole threads went well. Let's hope that a stiffer linkage and better end bearings make the necessity for a center mount a moot point. Get the torsion springs on for the return and you may not miss the center point at all.

That's normal. The air that comes out of the vents in the dash is not heated. With some of the air conditioning set-ups, those vents may be cooled, but they are never heated.