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New Z owner, wondering what i actually bought...


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Hey guys, 

 

I first heard about this awesome little corner of the interwebs when Skib (i think it was) came over to the NPORA forums with his newly acquired Pathfinder, mentioned he was a mod here and i had to check it out. GLAD I DID!! So much good info here!

 

I am soon to be purchasing a 1977 280Z off my Father, which he bought back in 2012, as a fun little toy for him and i. But it turns out, these old datsun's just need a bit too much work for him to be happy with, so he went out and pick up an 07' Vette, for his mid life crisis.  

 

He bought the Z off a younger gentlemen in Wenatchee WA. He has a done a fair bit of changes to the car. And what my question to you is, what exactly am i working with? I have done a fair amount research (increasingly more as i get closer to purchasing it) and i have discovered a few changes on my own, and would like confirmation on what i think it has, and enlightenment on what im unsure about. I ask for your help because it runs sorta rough, has since we bought it, it will run and pulls fairly well, but its sorta laggy, and idles rough when warm. I tried playing with the timing a little bit, but it didn't change much. At any rate, here a some photos i have taken over that last three years its been at the house. 

 

Original sale photo.

 

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at the house

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The outside i think i have figured out, Euro Bumpers, either original or repo. XXR cheapo watanabe style wheels, rear louvers. HE had cut the springs, but my dad and i installed eibach's with some new KYB's. And i fairly sure that's about it. Correct me if i'm wrong.

 

Engine/ engine bay wiring pics. This is where i could use some assistance.

 

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Here is what i have been able to work out, 240SX  throttle body ( i think) EVAP delete, EGR delete (welded the intake hole shut or do non EGR intakes have that where an EGR would normally go?) Cold idle delete,  and then A/C delete, which, to a fine eyed view might only notice is just the pump. there rest of the plumbing and condenser is still there.It was included with the car, just not installed,  :w00t:

 

And then my dad had the 6 to 1 exhaust installed, which is an MSA unit if my memory serves correct. We also did a minor service to it a few weeks before putting it away for the 2014-2015 winter. Cap, rotor, and plugs, not the wires however. Didn't really change how the car felt or idled. 

 

 

But here is where i might need help, the injectors. Im fairly sure they are not OE and maybe attribute to the rough running. What happens is it will start cold around 700-800 RPMs, and then once its warm,it will idle at 1000 (indicated) RPM's, and just doesn't sound smooth. i'm not all too familiar with what a bad engine sounds like, but this one doesn't sound like i believe it should. I think it might be missing, I can take a video tomorrow of cold start, to idle and warm idle if that helps. 

 

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Also, i have some questions on the wiring. I've got a hold of the colored wiring diagram for the 77 Z and some things don't match. One of which is the grounds. Should there be a ground running to the started and the firewall? Because the diagram doesn't indicate that a ground runs to the starter. Just let me know if you see something out of the ordinary. Thanks

 

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I did the fusible link delete and replaced it with some AGU fuses, after changing the alternator with a Z-man remanufactured unit and i thought it wasn't charging. 

 

 

That's all i have for you guys. Its a little late at night for me. Just a fair warning, i know there will be some grammatical and spelling errors, please forgive me and ask any clarifying questions needed! 

 

Thanks in advance, looking forward to checking out the forums more in depth soon!!

 

-Kyle

 

 

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Kyle... great looking Z and one of the years when they still actually looked like a Z! Very clean inside and out.

 

The starter draws the most current on the vehicle, hundreds of amps when starting, so a good solid power wire to the starter and a good solid ground return is very important. As the battery is mounted so far back it's a good idea to have the ground to one of the transmission or even the starter mounting bolts. On the 4 cylinder the ground is to the head just above the alternator.

 

The '77 would have an external voltage regulator and '78s and on the regulator is built into the alternators. I don't see a regulator so perhaps yours has been 'converted' to use a later alternator? If you have charging issues and you do have a regulator I don't see, possibly a later internally regulated alternator was swapped in by mistake?

 

I'm no EFI expert but there is a throttle position switch on the throttle body. It tells the EFI if at idle or at full throttle. Anything in between and the EFI just uses it's internal fuel map for mixtures. At full throttle this is overridden and runs richer for performance. Idle (or foot off the gas deceleration) has it's own mixture settings so if this switch isn't set right the EFI could easily be fooled into thinking you are not idling but running at light throttle.

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Nice looking car there!  All the injector connectors appear to have been changed at some point due to the splices seen in the pics.  Check all those connectors inside for any type of corrosion which will usually look kinda green.  The connector on the tps is similar. If you find any of that clean them out well and use a little bit of dielectric grease when you reassemble.   Also, the hose between your throttle body and maf looks a little short.  make sure there's no leaks there

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Also, i have some questions on the wiring. I've got a hold of the colored wiring diagram for the 77 Z and some things don't match. One of which is the grounds. Should there be a ground running to the started and the firewall? Because the diagram doesn't indicate that a ground runs to the starter. Just let me know if you see something out of the ordinary. Thanks

 

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Just to make sure we are on the same page, the top pic has you holding the positive wire running directly to the starter, correct?

 

The second pic shows the ground cable connected to the body, along with a red wire coming from the harness. Where does that wire from the harness originate? Normally you will see connections of that variety on the positive side of the battery.

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Whooooa... this is totally wrong!!!

 

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The ground strap has to go to the engine block. The starter draws hundreds of amps current during start. It needs a good solid cable for ground return. The block is insulated from the body by rubber mounts, so is the transmission and differential. Rad hoses are rubber too. That thick cable should be on the starter mounting bolt or transmission mounting bolt to the engine block. There should also be a (smaller) wire to the body to ground it also but the biggest cable to the block.

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I can only speak for a 1975, so anybody who disagrees should correct me if this is different on a 1977.

 

Mike is right!  I suspect the starter doesn't work to well for very long without getting very hot searching for a good ground.

 

Disconnect the heavy ground cable from the bolt on the firewall and move it to under the bolt on the bell housing just above the starter.  Make sure it is clean and tight.  This will correctly ground the block to the battery.

 

Disconnect the black wire (fusible link) from the battery connector and put it under the bolt on the firewall.  Add an additional wire from that bolt to the - (negative) battery connector.  This provides the ground for the ECU and the two other large relays above the ECU in the cabin.  

 

What is further confusing... look closely at the two heavy red wires?   Notice that the both disappear into the wrapped harness and go across the firewall and join the big harness that goes through the rubber grommet into the cabin.

 

One connects to the + (positive) battery post, has a fusible link in it, and goes into the harness as you see it and across the firewall, joins the EFI harness and go into cabin somewhere in the mass of connectors to the left of clutch pedal to carry +12 volts to the ECU, fuel pump relay, etc.   Then a different (but same color and size) red wire comes back out the large EFI harness grommet back up to and across the firewall and connects to the ground screw with another fusible link.  (Datsun must have only wanted to purchase that size wire in RED only, so you have both + and - red wires running in the wrapped harness running across the firewall.)   Some cars also had a red or black wire from that firewall connection over to the - (negative) battery post.

 

I looks to me you may have a fusible link (or fuse) running from the + (positive) battery post and connecting to the large red wire.  I couldn't make sure where from the pictures.

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Thanks guys for the replies! I'm sorry for not clarifying some of the wiring and just leaving it open for you guys to guess. My bad. I'm on my phone so I can't multi quote, so bare with me here.

 

Datzenmike- thanks for the compliments sir, I've really fallen in love with her, which is good, because she's gonna need a Lotta love to get her up to my standards. There is a ground that runs from the starter to the side terminal of the batter, as well as the chassis ground. So good to know that's correct, the factory wiring diagram isn't very clear on that.

The voltage regulator is still there, and it resides under the plate/panel in front of the battery, I'd like to delete it, but as the alt was just replaced with an internally regulated unit (against my recommendations) I'm gonna leave it unit I need a new one or need more power.

As for the throttle body, I'll take a look at calibrating the TPS, is there a document that shows how to do that, or should I just find a 240Sx FSM and follow it's procedure for TPS calibration?

 

5150 WII - I'll give the harness a good look through and see if I can find any corrosion on the important connectors. Thanks for the tip!

 

Ericsb210 - The top photo you quoted is the starter ground that went to negative side battery terminal, the second quoted photo shows the chassis ground going to the top negative battery post, is wired a little weird. I'm going to move the battery to behind the passenger because I hate the factory position. The smaller red wire is the factory ground shown in the wiring manual, the one that has that quick disconnect.

 

Gotta go to work, I'll reply more on lunch or when I get home.

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