Captain Obvious

Cool. That makes sense. Thanks for filling in the blanks.

Man, that sucks. I'll keep my eyes and ears open.

As mentioned above, the FI get's it's trigger off the negative side of the coil. Since we're talking about this kind of stuff though... I've always wondered about the possibility that the multiple spark discharge systems screw with the fuel injection? Isn't there a risk that the ECU will misinterpret the multiple discharges and pulse the injectors more often than is desired. I'm assuming it doesn't cause a problem since you're not the first to pair an ignition system like that with the stock fuel injection, but just wondering if anyone has had issues with that.

What I want to know is... Was it YOU who was doing donuts in that parking lot, or where those marks there before you got there? Supposedly.

Last time I talked to Superlen, he had completed his home built flow bench and had poked around with a couple AFMs. I betcha he knows. And if we're lucky, he'll be able to come up for air sometime soon!

Absolutely. Cross drilling and plugging that way would work great too. I was gonna mention that, but I thought for some reason that you didn't want the modification to show. I was reading too much into it, and even so, you could always do the plugging from the underside and that way it'll be invisible after installation. I'm not sure you're going to want pipe threads though for the job though. You're need to drill and tap deep enough that you'll completely eclipse the cross hole and I'm thinking that straight threads would be better for the application. Another cross plug option would be to drill (without tapping) and shrink fit an aluminum plug into the hole. Size the hole and the plug such that with a little heat on the manifold and a little cool on the plug... Press the plug in, grind off the excess, and it'll be pretty much invisible when done. Just make sure you use aluminum for the plug so the thermal expansions are matched.

So here's a question. When was the last time you had the car at a more typical altitude? Did you still have the same problem when you were down off the peak? And I'm not sure that really even has anything to do with it... I could see running at altitude would make you run richer than necessary because the air is so thin, but how could it drop the gas mileage to an unreasonably low value. Think about it this way. Your car runs great at 1000 feet. Gas mileage is 20 mpg. Then you drive up to 10000 feet and the car runs rich. But the gas mileage should still be the same since the injector pulses are still the same width. In other words, the altitude increase won't make the pulses wider, they'll be the same width but are now wider than necessary. (Haha! Did I say that right? ) Just tossing out ideas...

Maybe it's just me, but I'd be skittish about using any type of plastic or rubber to plug that hole. I'd want something with a positive retention feature of some sort. If a chunk of something comes off or out of that hole, it's going straight into your intake valve. I'd want to use some sort of metal and I'd want it welded into place or retained with threads of some sort. I know I'm conservative when it comes to that kind of stuff, but I'd sleep easier. Some ideas? Drill out the end plug and tap the hole as you already suggested. Find or make a tap short enough to be able to stick it into the hole and tap it with quarter turns right through the circular runner opening. That way you won't have to drill out the end plug? Then use a set screw to plug the hole (with thread locker) and grind off any excess. Make a two piece tapered plug contraption, one with a male thread and one with a female. Put one in runner 1 side and the other in runner 2 side and then thread them together (with thread lock) from one side to the other? Grind off any excess. And of course, the obvious of weld one side shut. Someone trained in the art of aluminum welding ought to be able to make easy work out of that. Wonder why they only connected 1 and 2...

I'm more confused by the blanket statements from post #4. That's what started all the discussion: I'm guessing what you really meant to say was: The AFM only provides mixture measurement and correction until it maxes out full open. And if the Z is like a lot of other cars, a full open maxed out AFM could occur as low as 4500 RPM if the throttle is full open. And if the AFM maxes out full open, beyond that point the ECU calculates IDC entirely based on RPM, TPS signal and CTS. Note that I've not tested this for confirmation, so I cannot attest as to the accuracy of the statement, but it sure makes more sense to me and I'm thinking it's at least a lot closer to what you really meant?

BCDD should have no effect on mixture at all. All it does is provide a path around the throttle plate. Think of it as an idle speed control. I'm not going to rule anything out at this point, but the BCDD shouldn't have anything to do with this. As for an altitude switch, I looked through the manuals as well and I don't see any mention of the altitude switch prior to 77. I'm thinking they added that for the 77 year and beyond. I agree with FW in that I wouldn't go shorting pins on the ECU. Probably wouldn't cause any problem, but not worth the risk. So unless you're triple positive sure you've got the right injectors in there, you need to address that. Where (and when) did you get your replacement injectors? Did they come with the car or did you put them in?

10 MPG ought to be easier to find than this... Those plugs don't look all black and sooty as I would have expected. At 10 MPG, I would have expected loose fluffy.

I've not gotten to that part of the circuitry yet, and I may never get there. but I'm not buying the 4500 RPM limit either. It takes much more air and fuel to run WOT up a steep hill at 4500 RPM than it does sitting still no load in neutral at 4500 RPM in the driveway. There's no way you would want the same amount of fuel injected under both of those conditions. I won't deny it if someone shows me the circuitry or the test results, but until then... I'm not buying it.

Great! Repair looks good and it sounds like you're back to reasonable numbers for where to put the screws. Glad you found someone who had the welding skills to do the repair!

I'm traveling so my resources are very spotty, but I can tell you that pin 6 Is a ground line. It's an analog ground for the sensor, so yes, those two parts ARE in series, but not in the usual sense. Yes, if the temp sensor in the AFM has gone open circuit, you will run rich.

Sorry to hear about the continued troubles. Are you sure you're using appropriate injectors? And have you ever tried another ECU just to see what happens? Wish we were closer together, I'd be happy to do what I could to help.

Forgot to ask... Which ECU is running? Is it that newer one with the DIPs?

Excellent! So now it's on to the next hottest fire I assume. Liked the thumbs up BTW!

Here's a bunch of details of what I did: http://www.classiczcars.com/topic/48758-suspension-refresh/ http://www.classiczcars.com/topic/48621-steering-rack-disassembly-and-refurb/

I'll offer another perspective... I've seen several incorrectly fitting and incorrectly installed poly bushings in my travels. I know for a fact that on my car, my PO had installed poly bushings everywhere and the car felt horrible and handled like crap. I took most of the poly out and replaced with rubber, but during that process I found a long laundry list of issues with the whole job. Some bushings designed poorly and not fitting properly. Some bushings installed incorrectly. Some related suspension bits not put back together in the right order and/or orientation. I bet that if the bushings are designed properly, fit right, and are installed properly the car will feel very different than what happens on a lot of installs. In other words, I believe that some of the suspension issues that are attributed to poly bushings might not be the bushing's fault. The bottom line is that if you're going to compare a poly install with a rubber install, you better make sure both installs were done right or you might not be doing a fair evaluation.

I've not seen that phenomenon on the round top carbs, but I've seen it on the 280 throttle body as well as other throttle bodies from other unrelated cars as well. Perfectly smooth when off, but sticky with vacuum pulling against the butterfly plate with the engine running. I won't claim to fully understand exactly what's going on, but in my experience it's been caused by either worn throttle butterfly shafts as suggested above, or by dirty crud on the butterfly and/or throat walls where the butterfly meets the walls. So first suggestion would be to hold the carbs butterflies completely open and thoroughly clean the the interior walls of the carbs and the butterflies really well with a carb cleaner wetted rag. Might be tough with the carbs on the car, but you could remove the domes and suction pistons and that might allow enough room to get in there without taking the carbs completely off. If that doesn't help, then I suspect the chrome plating has worn off your throttle shafts exposing the brass underneath (very likely). You could put some lube on the shafts and work them around. That may help temporarily, but to really fix it, you'll need more dramatic measures.

Excellent. I love it when a plan comes together. Good thinking on the cable re-route to make future work easier. I should have done that too. This whole thing reminds me that I gotta pull my dash... I've got a leaking heater core and I also need to do some electrical work for a headlight relay upgrade. Easier if I just pull the whole dash. My car has been in hibernation, but Z season is fast approaching! If I remember, I'll reroute that cable while the dash is out.

They probably put that aluminum portion at the bottom of the cup to add additional material for threads. And they probably used aluminum because it's easier to machine than steel. It's clearly swaged/peened in place and I doubt you would be able to get it out in good enough shape to be able to bend it a third time back into place without cracking it. In fact, I doubt you'd even be able to get it out without cracking off the material that's been bent into retaining position. Hmmm... So ideas? 1) Drill it out, make a polished aluminum replacement with a few threads on the inside and use a nut to hold it in place. You got room for a nut on the inside? 2) Drill it out, make a steel replacement, silver braze it into place, and send the whole thing off for plating as a unit. 3) Carefully drill/grind off as little of the the peened material off the inside required to get it out and then JB weld it back into place after plating. It's gotta hold vacuum, right?

Wow! Shiny!! That's a great finish! PS - I see you!!

John, Thanks from me too.

Cool. I'm assuming this is one of those electronic flashers we were talking about near the top of the thread? Did your flashy bulb burn out already, or are you just planning ahead?