1977 280z EFI Nightmare

[Captain Obvious]

The PCV hoses, while kludgy, are connected fine. The valve cover is correctly connected upstream of the throttle butterfly.

Two things catch my eye quickly... First, your fusible links are in the wrong locations. You've got the large BLK link in the back position, and it should be in the front position. It won't explain the performance issues you're having, but fix them now before something goes wrong.

They should look like this. The largest link should be the front outboard position:

Second, I'm not liking the tube connected to the vacuum port on the bottom of the throttle body... There are two vacuum connections on the throttle body, one that points toward the front of the car, and one that points towards the rear. The one pointing forward is for the distributor vacuum (and carbon can). The one pointing to the rear is for the EGR system.

What I'm not liking is there is a hose connected to the vacuum nipple that is pointing rearwards, but you've removed the EGR system. That nipple should be capped off with no tube attached. The hoes you have connected to it seems to wrap around underneath the throttle body, and my suspicion is that you're using it for distributor advance. Is that the case?

And lastly... The temperature sensor is often the culprit in lots of EFI issues. Have you taken meter measurements to make sure it's working properly?

[ckurtz2]

@Captain Obvious

Great catch! Could of just save me my car in the future:)

Now the connection pointing towards the rear is the one for the BCDD correct? In my sixth photo. Actually looking at it I don't think it is. Anyways, I can't remember why I did it, I think I saw a diagram somewhere online. But I believe I have that running to the smallest line on the carbon canister. No idea if that is right. I had tons of photos on my phone when I disassembled the motor, but broke the phone before I got it back together, and didn't have the photos on the cloud. Was a catastrophe for me pulling up diagrams and what not. I remember connections like this confused me.

 

Regarding the forward pointing vacuum port, which one are you talking about? 

[ckurtz2]

@Zed Head

Just the information I was looking for regarding the PCV. Great idea! BAT definitely may come in handy

[Captain Obvious]

Here's some pics of the throttle body. You can see there are two small vacuum tube connection nipples on the bottom.

The nipple on the left in the pic (points toward the radiator) should run to a "T" and from that T, it runs to both the carbon can and the distributor vacuum. The nipple on the right points downward towards the rear of the car is used for the EGR system (and only the EGR). So if you've removed the EGR stuff, you can cap that one off completely.

Here's a closer-upper of the nipples. You want to use the one on the left and cap off the one on the right.:

Edited March 29, 2021 by Captain Obvious
fat fingers

[Captain Obvious]

IMHO, I think the two first steps would be to a) make sure the electrical connections to the EFI system are clean, tight, and making really good connection. Paying special attention to the temp sensor and the AFM, and b) simplify as much of the tubing as you can in order to minimize vacuum leaks. After you have simplified and gotten the basic system leak free and running well, you can start adding stuff back in.

For example... For now, you can just cap off all the stuff running to the carbon can. You can also take off everything having to do with the AAR. The car will idle low until it warms up, but once it's warmed up, the AAR should be doing nothing anyway. I don't remember what they use the TVV stuff for... If it's EGR and EGR only, then you can cap all that stuff off too.

Just trying to minimize all the tubing because each end of any tube is a potential vacuum leak. Make it leak free, get the basic system working, and then start putting stuff back on.

[ckurtz2]

@Captain Obvious

I know 100% then that I have the throttle body vacuum messed up, not sure how I have it setup until I get home this weekend. I will let you know then. Plans are to get the new rear main seal, freeze plug, lightweight flywheel, clutch, and  trans into the car this weekend. Switched to the 81zx 5speed for that nice overdrive. Still probably a month out till the motor is safe to run and begin diagnosing again. I need to figure out which driveshaft I need, whether the 81zx, or the one that came with the car (seem to be about 1/2  to 3/4 inch different in length) rebuild it and toss it into the car. As well as decide which clutch collar I need to use, whether from the 4speed that came with my car, or the one from the 5speed. Seems to be some debate with that, because it says to use the proper collar with the clutch it is meant for. But my clutch is an ACT aftermarket clutch for the coupe models with the smaller coupe flywheel. I got it from here... https://www.autohance.com/act-nx1-hdss-clutch-kit-heavy-duty-hd.html?gclid=EAIaIQobChMIhISB4qnW7wIVTx6tBh0pFQwAEAQYBCABEgJDpvD_BwE . Which is compatible from 1975 all the way through the 90s. I don't know if it actually matters what collar I use.  If you have any advice that would be wonderful.

You are right. Going to start with a compression check. Then I think I will test the water temp sensor and then AFM. If those check out I believe it is going to be my vacuum issue you recommended. Like you said, peel away the layers on that onion haha. Thank you everyone so far for helping me out, I have been on my own for a while now and it is really nice to get some advice.

Found this, which will come useful when testing the AFM and such.

280z EFI Bible

[siteunseen]

I started "ripping and tearing" the emission stuff off mine. That little hose on the right of the throttle body had me stuck dead in the water. I do believe Mr Obvious saved my arse on that as he has many times. Thank you @Captain Obvious if I haven't told you lately.

 

[ckurtz2]

@siteunseen

Seeing Rod Stewart, this song, and your comment was just perfect.🤣 

[S30Driver]

Your original driveshaft should be the one to use with the 5 speed.

Carefully compare the height of the original clutch pressure plate with the new act one.   If they measure the same height, use the original collar.  If not, you will need one of the correct height to go with the act plate.    Search for the many threads on how to measure this.

[Captain Obvious]

2 hours ago, siteunseen said:

 I do believe Mr Obvious saved my arse

LOL. Glad to help my friend!!  I'm just a guy with a Z who types a lot, but I try to add value where I think I can.  

[Captain Obvious]

5 hours ago, ckurtz2 said:

Found this, which will come useful when testing the AFM and such.

280z EFI Bible

Yes, read through the EFI bible. And then read through it again.

Compression test. Intake manifold vacuum test. Fuel pressure test. Ohmmeter tests. Ignition timing test.

And if you have a few extra minutes, clean some connectors. If you're looking for a place to start, start in the passenger footwell where the heater core leaked and corroded the connectors on the passenger side of the trans tunnel. Also do the temp sensor, the AFM, the fusible links and the fuse block.

There are other people who can add much more value about the transmission and driveshaft stuff than I can. I could survive in the wild there if I had to, but there are other people who are experts in that area that will cover you there.

[ckurtz2]

4 hours ago, S30Driver said:

Your original driveshaft should be the one to use with the 5 speed.

Carefully compare the height of the original clutch pressure plate with the new act one.   If they measure the same height, use the original collar.  If not, you will need one of the correct height to go with the act plate.    Search for the many threads on how to measure this.

Best thread I found was this.

What you recommend makes absolute sense to me. Thanks! Do I just measure the PP heights, or do I set the PPs on top of their corresponding flywheels and then measure? Reason I ask is because I am using a Fidanza flywheel and it may be different from the chunky original.

@Captain Obvious   Roger. I will get back to you in the future with the demons that I come across. I am sure I will need assistance doing away with them🙃