1977 280z EFI Nightmare

[Zed Head]

1 hour ago, ckurtz2 said:

However, for now I am trying to get the system to function as it should without any extras,

It has been proposed that either today's fuel is not the same as in the 70's, or that the electronic components in the ECU's have aged.  Either way, without a time machine your quest might be impossible.

The AFM's from MSA seem to run rich.  So one of those might get you closer.  But might cause problems if you need to pass emissions.  Good luck.

I think that I already commented on the 180 versus 150 measurement.  I don't think it matters.  "Approximately 150 ohms" just means there should be "some" resistance.

Edited May 13, 2021 by Zed Head
added as

[ckurtz2]

@siteunseen thank you for the help! I have some good news for today

 

So I decided to just swap the AFM as a future investment for the car. It had been tampered with previously before I got the car, so I had no idea where the OEM specs were for the cog. Picked it up from zcarsource about 20 minutes from my house.

Slapped it in and WHAM nothin, though it may have ran just a tad better. I also bench tested it, and the specs were a little closer to the online manual's. @siteunseen You were right though, the 150ohm didn't matter.

I pinched the return line briefly and it started leaks all over the fuel rail showering a highly pressured mist, so that with the pressure test confirmed the fuel pressure is solid. Also good to note I have a new pressure regulator.

I hadn't timed the car since the first start, and after fixing all the vacuum leaks it had me wondering. So while the car was running I moved the distributor and wellah! Idled much better (was still popping out the intake) and I could actually free rev it. It seemed like it wanted more, so i pulled the bolt out and twisted it past the little mount it had. Here, it ran even better, although when the car is warm it still stumbles at idle. However, it now free revs as I imagine the car should, and sounds healthier. So, what could this mean? Should I do some tests on the dizzy like if the vacuum advance works and such. Educate me, cause I am an idiot. So far my best theory is that somehow I messed up the mechanical timing and the ignition timing is compensating. Now that fuel and vacuum and the EFI system is set, its a matter of timing this puppy.

When running the timing light I could see that it was off of the pulley indicator and was reading somewhere in the negatives.

Here is a photo of what the dizzy is set to temporarily. We are close to settling this engines demons once and for all.

 

 

 

[siteunseen]

I have mine at full advance and it runs fine. By that I mean loosened the bolt and turned it all the way clockwise. Fyi, I'm not any kind of trained mechanic just seat of the pants and what sounds good to my ears. You seem curious to figure it out which is good in my opinion.

[ckurtz2]

No worries, you are still a huge help. I am just a college kid with a dream and set of tools so🙃. I am pretty much wondering why I need to push the distributor past the stock adjustment plate to get it to run right. I know the timing is off, but I don't know why it is off so much. Even at that point it still stumbles a little bit, the engine is just 1000% happier running like that then it was before at 10deg btdc like the sticker on the hood recommended. 

[S30Driver]

Remember, when you check the timing with a light, to get a accurate reading, you need to disable the distributors vacuum advance.  Unplug its vacuum line and cap it so you don't have a leak.

[Patcon]

There should be another bolt on the distributor that faces downward. It will add a little more adjustment range. It's possible the distributor quill is not exactly in the right place.

Or the plugs wires aren't in the normal locations

[siteunseen]

[ckurtz2]

I did not know that the vacuum advance was supposed to be capped. Great tip, thank you. Which bolt are you referring to? I checked all around and all I could find were the two mounting bolts and the adjustment bolt. In addition I checked my firing order, all looked good there!

[ckurtz2]

I stand corrected. I am praying that this might rest the demons once and for all. I had the firing order different, adjusted after the following photo I attached. Is this wrong? If it is I wonder how the hell this car ran enough to even try and idle. 

 

Now that I look at it though, the order seems the same, the distributor just seems rotated on one of the photos. Correct me if I am wrong

Edited May 14, 2021 by ckurtz2
I noticed something

[siteunseen]

Look for the vertical line molded in the cap. That's #1.

 

http://atlanticz.ca/zclub/techtips/distributor/correction.jpg

 

 

Edited May 14, 2021 by siteunseen

[Zed Head]

Actually, not trying to one-up anyone, but the vacuum advance on the Z's is ported vacuum.  So it's closed at idle, no vacuum.  But, if you have the vacuum advance hose on the wrong port you might get full vacuum advance at idle.  Which would screw up your timing light reading and your idle timing.  I'd hook up the light, then remove the vacuum hose.  If timing changes the hose is on the wrong port.

If you're still not sure of firing order and timing, then set your damper pulley mark at zero to ten and remove the distributor cap.  The rotor should be pointing at whatever terminal is "number 1".  Move your number one wire to that terminal and check your timing again.  If things are screwed up then you might have a problem with your damper. 

Make sure you know where you started so you can at least get back there if things don't work.

[Patcon]

The two pieces of metal that slide to adjust timing.  One is bolted to the bottom of the upper part of the distributor. That bolt should be in a slotted hole