1977 280z EFI Nightmare

[Zed Head]

I'm not sure where you're getting your specs. from.  AFM Test #2 in the 1980 EFI book says ~150 ohms, not zero.  And 60 ohms is the typical resistance of a relay solenoid so I think that those are probably right also.

And, yes, leaking injector seals would be a big problem.  Those are kind of hard to install wrong but it does happen.  Lube them up well and maybe install each injector separately before installing the rail.  It's tempting to try to do it with them all on the rail but it can cause problems, especially with the three piece 77 rail.  Make sure that the injector securing pieces are not cracked and that the screws are giving good clamping force.

Intake manifold torque values are in the FSM, probably in the engine Mechanical chapter, but I remember something like 11 ft-lbs.  It's like one hand on a ratchet wrench tight.

Here is AFM Test #2 on page 75 of the 1980 EFI book.

20 hours ago, ckurtz2 said:

AFM #2: Fail

183 ohms. Should be 0

 

[ckurtz2]

24 minutes ago, Zed Head said:

I'm not sure where you're getting your specs. from.  AFM Test #2 in the 1980 EFI book says ~150 ohms, not zero.  And 60 ohms is the typical resistance of a relay solenoid so I think that those are probably right also.

Ok that's good to know. I got my specs from 280z EFI Bible . Who knows it may be wrong. The test I am talking about was the AFM #2 or 3b. I guess it says small resistance, but I am not sure what it considers small.

Also thank you @Zed Head for listening to me. I know I am posting a ton, but it is a good way for me to log what is happening as I go along, and any advice given has been super helpful.

 

In addition, I can confirm that one of the injector seals was leaking (nearest the front of the engine where I heard hissing). It had a big tear across the small o-ring. In addition, I spilt water all over the intake and let it dry before I loosened any bolts. I hoped that the water would find its way around the manifold and seep into areas where the gasket was leaking. It turns out that a large part of the intake gasket was moist where I could hear the engine hissing. Do you think it's possible the gasket is bad here? the nuts were torqued on pretty tight, so I don't think it was too loose, but I could have been wrong. I actually think it was way over torqued. Here are some photos of what I mean. On the intake itself, you can also see where fuel seepage was happening. If I over torqued things is the gasket reusable? I put it on in January as new.

 

Edited May 2, 2021 by ckurtz2

[Zed Head]

Actually it looks like it was sealing where it needed to seal.  Which way are you installing the yokes?  They should have the edges pointing toward the manifolds, with the nut riding on the top of the curve.

You're making progress.  Use this EFI book, it has all years through 1980 listed.  1975 was their first shot at publishing a guide so it might have errors.

 

[ckurtz2]

1 minute ago, Zed Head said:

Actually it looks like it was sealing where it needed to seal.  Which way are you installing the yokes?  They should have the edges pointing toward the manifolds, with the nut riding on the top of the curve.

I had the yokes the proper way, I had to use two washers for one of the mounts though, because I was missing one on the car to begin with. Can I just reuse this same gasket and plug everything up properly torqued this time? It was new in January.

Then my big leak must have been that injector seal, praying that is was at least haha. There's not much more for me to look at for vacuum problems once everything is back together. 

[ckurtz2]

Also, thank you for that guide! I am going to start using that one:)

[Captain Obvious]

Good progress. One layer at a time.

I wouldn't worry too much about the AFM numbers right now. I've seen a couple anomalous readings from AFM's that worked great on the car. Might not be a problem there.

I gotta admit though that with so much going on a the same time that I'm getting a little lost on what you're working on... Is there one test that is giving you trouble that you need help with? Pick one and work through it? Then move on to the next?

[ckurtz2]

@Captain Obvious

Yeah sorry about that, I kind of just updated things as I went...I just went very quickly haha. Essentially, it has been narrowed down that the main cause of my motor running like crap is not electronic, however the AFM may be slightly at fault. However, with a vacuum test it showed I had 0 vac at idle. Which is confusing to say the least, but I have never used this vac gauge before. However, I also pulled several vacuum ports and tried to plug with my finger and I felt no suction, and the motor did not run worse. So it must have poor vacuum. However, I think it must have some vacuum, because when I give it throttle the AFM meter moves too. In addition, since I did those previous vacuum fixes you mentioned a long time ago I am now able to rev it. I could not do that in January. So progress is being made, no matter how small.

I heard hissing coming from where injector 1 was. I pulled off the rail and saw that the seal was ripped and not seated. Another vacuum leak right there. I also saw that many other injectors were not seated properly. Likely due to my stupidity of not greasing them before the first install. Learned my lesson:) So tomorrow that will get replaced. In addition, I removed the intake and exhaust and put them back on making sure they are torqued properly. Essentially, I am taking no **** from this car and finding every vacuum leak possible:). 

If the car still runs like marbles, well I will cry myself to sleep, burn the car to the ground, curse the heavens, or take it as a taunting from the car for a hammer. Lets hope it doesn't come to that🤠

[Captain Obvious]

11 minutes ago, ckurtz2 said:

take it as a taunting from the car

Now go away, or I shall taunt you a second time!   

Injectors leaking air is a big deal. Take care of that and we'll see what happens next.

[ckurtz2]

          Hey guys I am back. New injector seals seated nicely. I was on a camping trip so just got back to working on the car. Anyways, fired it up, and it ran about the same, I can still hear a hissing in the same spot. The only other spot that I could imagine be leaking vacuum is the vent PCV hose from the block to the intake near the headers. I pulled it and it definitely had cracks, but looking from the inside shining a light and bending the hose it looks like none of the cracks go through. I still think it needs replacement, I just can't find one in stock. I also for the hell of it loosed the cog tension on the AFM about 4 teeth. It helped, but it still wanted more fuel, so I stopped knowing that something else is amiss.

         I had a new water temp sensor laying around so I decided to toss it in. There was a positive impact, but only marginal. So right now I am thinking a new AFM may be justified, but I am curious what you guys may think. I also redid all the engine bay wiring harness connectors, so those are now a solid connection. When revving the car I also noticed it would occasionally pop through the intake, so maybe my ignition timing is off? It is just hard to set it, because I can't keep the car to hold a steady idle when it is warm. Looking forward to hearing advice!

 

[siteunseen]

I'm sorry for not reading up the thread but something that I did once was put the valve cover gasket on upside down. There's a difference at the front and if you get it wrong it'll leave a little gap on the thermostat housing side.

Sorry again I don't know about the hissing, could be a snake up in there?

 

[Zed Head]

On 5/1/2021 at 3:44 PM, Zed Head said:

When you moved the AFM vane you were adding fuel.  Seems like a vacuum leak somewhere, or the typical "lean AFM/electronics" problem.  The "temp sensor tweak" is the cure for that.

Not sure what's going on with your voltages.  Are you sure there's not a decimal on the display?  What kind of meter?

http://www.atlanticz.ca/zclub/techtips/tempsensorpot/index.html

This modification really is worth trying.  It has worked for many many 280Z owners.

The hissing might be the FPR.  They hiss as fuel squeezes through.

[ckurtz2]

@siteunseen now that you mentioned it that had me thinking. Took a peep though and all looked good

@Zed Head that tweak is very intriguing, and I won't hesitate to use it as a last resort. However, for now I am trying to get the system to function as it should without any extras, but if she is too stubborn I'll just have to do it haha. 

Now, I pulled the AFM to give it a nice "bench test" instead of going through the car's wiring harness. Thought it would give a more accurate result. Everything was pretty much the same! 

However, between pins 7 and 8 I was reading 182.2. It is supposed to read "approximently 150ohm". In addition, pins 6 to 8 read exactly 182.2 (supposed to be 180 so that one checks out good). I found it interesting how both of these tests are the exact same resistance. What could that mean? What is the function of pins 7 to 8? Simply put, pins 7 to 8 have about 21.3% more resistance than it should, which isn't "approximately 150ohm". I am not afraid to put a new AFM from zcarsource on her, I just want to hear honest opinions of you think I should get it done.