1977 Cylinder #1 Mystery

[Captain Obvious]

8 minutes ago, Zed Head said:

Does the module number match the 1978 module? 

The 77 and 78 modules are significantly different mechanical form factor.

The 77 looks like this:

And the 78 looks like this. Slightly smaller and has a very different connection scheme:

[Zed Head]

I missed it, thanks.  77 is an odd year.  So, they kept the ballast resistor, which is a current-adjusting device, and opened the gap for the plugs.  So it's the intermediate step between 76 and 78.  76 had the same setup but a smaller gap.  Electronic module with ballast.

Who knows.  I thought there might be an advantage to a more modern module.  In the big scheme it just means he's still stuck with plug fouling, probably from the cam.  Oh well.

 

[Zed Head]

76 was pretty primitive despite the new electronic ignition.  Get the sand blaster out.

[Captain Obvious]

I think you have the chronology right. 74 through 76 used a smaller plug gap (presumably matched to the spark energy) and then in 77 they redesigned the module and increased the gap width (again, presumably matched to the spark energy).

Then in 78, they changed things again, but the plug gap stayed the same. (.039 - .043). They did, however, do away with the ballast resistor, so there could potentially be a hotter spark if you used a 78 module. I have dug into both, but don't remember the details of what I found inside the 78. I have pics, but don't remember the circuit details without checking my notes.

78 guts:

[Captain Obvious]

Oh, and I do have to say that as much as I like talking about dissecting and analyzing electronic goodies, I don't think this (ignition module chatter) has anything to do with ckurtz2 issues.

Edited April 8, 2022 by Captain Obvious

[Zed Head]

1 minute ago, Captain Obvious said:

Oh, and I do have to say that as much as I like talking about dissecting and analyzing electronic goodies, I don't think this (ignition module chatter) has anything to do with ckurtz2 issues.

It was a potential solution to the fouling plugs.

[Zed Head]

On 4/1/2022 at 4:01 PM, ckurtz2 said:

Now, I was super intrigued by your post as it would make sense. However, I remember playing with the idle enrichment screw on the AFM to see what was happening if the motor was lean or not. Lets just say I fouled some plugs whoops. But here was cylinder 1 compared to #2, Which I think pretty accurately confirms no boom🔥 is happening in #1:(

 

[Zed Head]

On 4/5/2022 at 4:41 PM, ckurtz2 said:

 HAH!, my tuning shop is Chuck from Sakura in AZ. I don't think any fancy computers or anything will be used, just the ole noggin. This is my first Z that has never quite run right, and they know a lot more about how Zs are supposed to look/run etc, and have a lot more experience in troubleshooting than I do. If I never get it quite perfect, so be it, but I want to get as close as possible. As long as it doesn't hurt the engine and is daily driveable, I can always swap to a different EMS later (with my track record with the EFI system on this car so far, it is seeming O so likely. I don't want to throw in the bag yet though).

It will be interesting to see what he comes up with.  I think he likes the later ECM's with NISTUNE.   @cgsheen1

Anyway, it's been an interesting discussion.  I learned something about the 77's.  Good luck.

 

[ckurtz2]

Lol, love to see the discussion, nice to learn something new:) 

Replaced plugs (gapped to 0.04), cylinder 5 came back to life. Ran waaay better, but it would still surge a little bit and miss. So I think that my whole electrical problem was fixed. Ended up being a loose plug at the dropping resistor, and spark plugs. Go figure, sometimes the most complicated of issues are quite simple. The new plugs are starting to already carbon foul again. So my plan is to replace the connections at the WT sensor.

     The vacuum sits at around 15.5hg so I think having it vacuum tested will be a very smart thing to do. And if it doesn't climb to something better, than another solution will have to be figured out. I think the main reason those plugs are fouling is due to the fuel pressure being too high (low vacuum means the fuel pressure climbs significantly:(. Maybe an interesting solution will be a fuel rail with a different fuel pressure regulator. Who knows at this point, time will tell. 

 

[Dave WM]

8 hours ago, ckurtz2 said:

Lol, love to see the discussion, nice to learn something new:) 

Replaced plugs (gapped to 0.04), cylinder 5 came back to life. Ran waaay better, but it would still surge a little bit and miss. So I think that my whole electrical problem was fixed. Ended up being a loose plug at the dropping resistor, and spark plugs. Go figure, sometimes the most complicated of issues are quite simple. The new plugs are starting to already carbon foul again. So my plan is to replace the connections at the WT sensor.

     The vacuum sits at around 15.5hg so I think having it vacuum tested will be a very smart thing to do. And if it doesn't climb to something better, than another solution will have to be figured out. I think the main reason those plugs are fouling is due to the fuel pressure being too high (low vacuum means the fuel pressure climbs significantly:(. Maybe an interesting solution will be a fuel rail with a different fuel pressure regulator. Who knows at this point, time will tell. 

 

vacuum will be effected by warm vs cold engine and ign timing as well. 

[ckurtz2]

      Yeah, I think my problem is all in the cam now. Here's a little update. Cleaned up tons of grounds today, and replaced several connectors as well. Once warmed up it idles way better than a few days ago, but still not quite right. Shakes and you can hear a miss every once and a while out the exhaust. Took it for a test drive, and it felt the best it ever has. About at quarter throttle it pulls pretty nice, sounds like all 6 are firing, and feels smooth overall. All of the problems I have noticed are at idle or WOT. So I tested WOT a few different ways. I put it at WOT at around 2100 rpm, no stumbling and it would pull harder and harder until about 3100 rpm and then miss to all hell. I then started from around 2000 rpm to about 3600 rpm at a quarter throttle and it didn't seem to miss at all. I then tried WOT after getting it to around 3200 rpm using a quarter throttle, didn't like that.(Note: I don't want to try things higher in rpm, because the cam is still technically breaking in). 

      Ok, cool. Figured this would happen. So I pulled plugs and yep all the ground electrodes are white as day and the outer edges of the plugs all have a little bit of black soot. So my visual diagnosis is rich at idle and waay lean under load and higher rpms. This will be the baseline, hopefully this issue will be able to be worked out with some tweaking. I also want to mention I had the potentiometer on and cranked about 1/4 of the way. Didn't want to toy with the AFM... not yet.  

     

[Captain Obvious]

Excellent. Clean and tight connections are your friend. And yes... It sounds like your issues are first order related to the cam now. Hope you can get that tuned in!

Do you have an air/fuel ratio meter, or are you doing this all old school?