@Zed Head also, I was reading through the FSM and it looks like testing it requires an oscilloscope. Is there something in here that usually goes bad that can be replaced without using one of those? It looks like there are quite a few of these modules.

The first most simple test is to watch the tachometer needle.

I've not heard of anybody who knows how to diagnose and fix them although somebody could probably figure it out. But the replacement optons are so cheap it's probably not worth the effort.

Here's a good how-to on a module replacement, with pictures of all of the parts inside. Who knows which part is bad.

https://www.classiczcars.com/files/file/64-1977-280z-replacing-the-tiu-with-a-hei-module/

7 minutes ago, Zed Head said:

The first most simple test is to watch the tachometer needle.

I've not heard of anybody who knows how to diagnose and fix them although somebody could probably figure it out. But the replacement optons are so cheap it's probably not worth the effort.

Here's a good how-to on a module replacement, with pictures of all of the parts inside. Who knows which part is bad.

https://www.classiczcars.com/files/file/64-1977-280z-replacing-the-tiu-with-a-hei-module/

I've been reading that the HEI module doesn't work as well and has issues with higher rpms. Have you had any luck with these in the past?

There also seem to be a variety of 4-pin HEI modules on amazon. Any idea which one it is?

Edited March 5Mar 5 by chaseincats

The guy that started that rumor, David Vizard, never backed it up with evidence.

I had a Standard Products HEI module on my engine. Worked great.

7 minutes ago, Zed Head said:

The guy that started that rumor, David Vizard, never backed it up with evidence.

I had a Standard Products HEI module on my engine. Worked great.

That's great to hear. It looks like a simple-enough installation but where did you find the square plug to connect it to the other side of the plug? I haven't been able to find a write-up for the 1978 version anywhere and the link you sent is for a 77 it seems.

Is this the one you bought? I also have a multi-spark system on the car but I don't recall the brand. I remember researching it a while ago and it is a brand that no longer exists but was highly regarded at the time. I can check it tonight. Would I need to pull that system?

Edited March 5Mar 5 by chaseincats

The multi-spark is probably the replacement for the factory module although I think that it can be wired to use the factory module as a trigger.

You need to figure out what you have. Look under the dash by the fusebox and see if the factory module is plugged in.

25 minutes ago, Zed Head said:

The multi-spark is probably the replacement for the factory module although I think that it can be wired to use the factory module as a trigger.

You need to figure out what you have. Look under the dash by the fusebox and see if the factory module is plugged in.

Will do when I get home from work - stand by

5 hours ago, Zed Head said:

The multi-spark is probably the replacement for the factory module although I think that it can be wired to use the factory module as a trigger.

You need to figure out what you have. Look under the dash by the fusebox and see if the factory module is plugged in.

@Zed Head I took a look and the original transistor box is plugged in and is the E12-27 8328 model. The multi-spark box and cable are "Jacobs Electronics." The coil has quite a few wires attached to it as a result.

Edited March 6Mar 6 by chaseincats

6 hours ago, chaseincats said:

I've been reading that the HEI module doesn't work as well and has issues with higher rpms. Have you had any luck with these in the past?

There also seem to be a variety of 4-pin HEI modules on amazon. Any idea which one it is?

I replaced my transistor ignition unit with an HEI module a few years back. Here is a link to my thread: https://www.classiczcars.com/forums/topic/68428-1976-280z-fuel-issues-troubleshooting/page/2/#comments

About 5 posts down on page 2 is where the fun starts. I currently do not have any issues at high RPMs, but I did with the original Transistor Ignition Unit. I think I also had to bypass the resistor under the ignition coil to get everything to work right. I also have a schematic of how I wired it up, but yours might be slightly different since it is a later model. Don't forget to apply the thermal paste to the back of the transistor on the the heat plate if you do choose to go this route. Good luck.

Here are some instructions about the later version of that system. Looks like it could be wired in different ways. I think that it intercepts takes the coil control from the ignition module and extends the spark generation. Or it can use the trigger from the distributor and control the coil itself.

Might want to hold off until you're sure you know what problem you're trying to solve. Good luck.

https://www.scribd.com/document/275126418/Jacobs-Electronics-Instructions-Pro-Street-Kit-372546-370506

Edited March 6Mar 6 by Zed Head

Update: I let the car sit for almost a week, started it Saturday to check for a rough idle, then started/drove it tonight (Monday). Both days the car started smoothly, so I'm assuming the rough-start idle issue was one of the injectors still being gummed up with the old gas and is now getting cleaned out after a few times of being ran.

I drove the same route with the same amount of vigor this evening while keeping an eye on the tach in case I experienced the fuel/spark cutout issue and I am happy to report there were no problems this time. I wonder if these are all little gremlins that are working themselves out now that the car is back on the road after so long?

Edited March 10Mar 10 by chaseincats

Update for you:

After driving the car quite a bit, it now starts smoothly which is great but was running quite lean. I pulled the plugs and they were very white - you can see that plug #3 looks very burned which makes sense since that was the cylinder that had the injector that wasn't fully working at start-ups.

I put a fuel pressure gauge on it today and here are the numbers: Idle: 32 psi w/15 on air fuel gauge (very lean) - Cruise: 36 psi w/15 on air fuel gauge (lean) - WOT: 40 psi w/13.2 on air fuel gauge (slightly lean for WOT but acceptable)

I then noticed the TPS's idle enrichment arm contact was dirty, so I grabbed some sand paper and gave it a good cleaning - the sandpaper came out black to my surprise. After that, I opened the AFM that we went through in the "tuning with an air fuel gauge" thread and moved the gear back and forth. I noticed for the first time that when turning the gear there is a very quiet click with each tooth when turned - I believe the position I had it in was in between one of these clicks. I richened it one click and the air fuel numbers are perfect now: idle - 13.8, cruise 14.5, WOT 12.8 and the car drives awesome.

Just for completions sake, I pulled out the fuel injection bible and went through all of the multimeter checks it provides, and everything came out normal.

I'll post another update in the coming weeks as it continues to wake itself out of hibernation. I will be checking the plug gap on all of these in the coming days too.

Edited March 16Mar 16 by chaseincats