Somethings wrong...

[ksechler]

7 hours ago, 240260280 said:

If plugs black then be sure to check efi system. Especially water temp sensor wiring.

Second that.  Sounds like an EFI issue to me too.

[Zed Head]

The running rich (black plugs) and the sudden dying are typical signs of a bad ECU OR a bad ECU connection.  People have reported wiggling the ECU connector while driving to fix it.  Maybe the fix of replacing the ECU really just fixed the connector issue.  And it's come back.  Might try wiggling the ECU connector, or pulling it off and putting it back on, just to see if it has an effect.  The rumbling might just be the engine loading up with fuel and fouling a few plugs.  Running on fewer cylinders for a while.

If wiggling the connector has an effect I'm not really sure what the long-term solution is.  But it would be a clue.  Could also be that a second ECU has gone bad.

[bartsscooterservice]

If the plugs are black, it's either over-fueling, or a bad spark or not enough air into the engine ( AFM )

Edited January 18, 2017 by bartsscooterservice

[gwri8]

I've been thinking on this Jai.  How long has it been since you've had a full tune-up?  Like Distributer cap, rotor, spark plugs, spark plug wires, timing, Air filter and fuel filter?  If I remember correctly, I changed the spark plugs well over a year ago.  Before that SteveJ, Tony and I replaced the vac lines, temp sensor and dist cap, not the rotor, added a G3 filter and kind of flushed out your fuel tank.  I know we did not do the spark plug wires.

Have any of those been replaced since then?  Regular maintenance can sometimes be a cure all for problems like this. I think before we can potentially diagnose an ecu or fuel problem a good tune-up would probably be in order.

All of the stuff I mentioned can be bought at your local Parts store. They might have to order a couple of things from another store but those parts should be available.

[Dave WM]

ZH mentioned ECU, that can cause a sudden issue, I had the same thing happen, Sudden loss of power then it just died. I replace the ECU and all was good, then put the old one back in and all was good, pointing to an intermittent ECU issue (or connector). Agree 1st thing to try would be to just remove and reconnect the 35 pin connector.

[zKars]

Start by replacing the coil. Instantaneous shut off is typically complete loss of spark related.  Next would be the transistorized coil firing module under the passenger side dash, THEN the ECU. Dirty plugs for whatever reasons don't act like on-off switches.

[240260280]

Missing spark could cause unburned fuel to accumulate and carbon-up things.

[Dave WM]

spark is easy, pull a plug attach the wire, lay it on the valve cover and look for a good strong spark while cranking.

[Zed Head]

She has the problem of sporadicity.  Checking for spark works when the engine won't start, but won't really help when she's rumbling down the road.  Always good to have a plan of action in place though, for when the problem happens.

And it's the rumbling that makes things not so clear.  The engine is running, just not well.  That's where a wire wiggle might show something.

[Redwing]

On 1/18/2017 at 4:20 PM, rcb280z said:

Check fusible links under the 2 white covers on the passenger side. I had a loose one once that would cause the car to stall out while driving.

I did, they are firmly attached.

Thanks

[Chickenman]

On 1/17/2017 at 7:12 PM, Redwing said:

I have a non working tach.  So rpm's are a guess.  Oh forgot to say, spark plugs are black dirty.  Tailpipe has soot too.  Well come on over and have fun fixing her.  Hahaha...

Thank you

Jai

Jai: Non working Tach and new plugs get sooty quickly?  That could be the Trignition box. First thing I would do is check the spark output as others have mentioned. Pull the coil lead out of the dizzy and hold it about 1/4" from the engine block ( Stat housing is good ). Have a helper crank the engine. You should get a sharp bluish/white spark with a bit of a " Snap " sound. A weak yellowish or orange spark is not good and may indicate a failing Trignition unit. Tach is also triggered through Trignition box. Edit: I can't remember what year your 280z is Jai, but 1975 and 1976 models had very low output Trignition boxes. 1977 and 1978's had more output.

If spark is very weak, check the coil wire resistance to make sure you don't have a bad coil wire. If that is OK then I would suspect the Trignition box is failing. Failure after a heat cycle is a common problem with old electronic systems. They fail when they get hot... then the components cool off and it works for a while. Sound familiar? BTW, A bad ground to the Trignition box can cause overheating of Internal components in the Trignition box.... so you may want to check that. 

It the Trignition box does turn out to be flaky, a 280ZX " Matchbox " Dizzy with the electronic module on the side of the dizzy is a great upgrade. Very strong spark and much more reliable than the old Trignition boxes.

Rock Auto has re-manufactured 1980 280ZX distributors for sale for $104.79 out right. Part #31619:

https://www.rockauto.com/en/catalog/nissan,1980,280zx,2.8l+l6,1209316,ignition,distributor,7108

The A1- Cardone re-man unit does not come with a Cap and Rotor, but you should be able to use your old 280Z cap and rotor if they are in good condition. If you need a new Cap and Rotor, go with OEM Nissan or buy the Beck Arnley parts from RA. The Beck Arnley parts are usually OEM Japanese made.

Keep us informed of what you find. GL.

Edited January 20, 2017 by Chickenman
Saw Jai's model year in Signature

[Redwing]

Hi,

Not much to report.  I've been thinking tho...  would it be a good idea to start diagnosing the first symptoms before jumping to the most current?  Redbird  started with the rumbling, this went on for about a month before moving to rumbling with some vibration.  What would have caused the vibration?   Wouldn't the vibration be something physically happening?  

Then entered the cutting off after rumbling with vibration.  The cut off has the feel of when I was driving with the bad ECU, and losing power.  I would imagine that these brief cut off's happening now,  will evolve to total stalling and refusing to start like before.  Maybe? 

This is the history I have on the repairs on RB.  

8/15/15  Steve   fuel pressure gauge installed, plugs, distributor cap, un-plugged cold start valve, added small fuel filter before pump.  U joints ok

8/29/15  Steve, Greg,   gas tank removed &  cleaned, added in cleaner into gas, replaced thermostat housing, temp sender, temp sensor & connector, thermostat gasket, charcoal canister filter,  PCV valve, & vac line from cannister to 3 way comm, to dizzy, & 2 short lines from there, thermal vac valve to vac delay valve hose, vac hose to EGR.  EGR gone, hose to it plugged.  All vac hoses replaced.  Idle adjust, screw seems not to work.  White cap on dash pot missing.  Timing not set, mark on harmonic balancer missing. Thermal vac valve to vac delay valve hose.  Delay valve missing.  Replaced rotor.  Replaced coil.  Replaced spark plug wires.

9/1/15 Loud clunk in rear end.

9/2/15  Greg  put car on jack stands, differential mount bad.  Replaced.

10/23/15 Steve, Tim, Greg, charged battery, cleaned fusible links added dielectric grease, cleaned ECU contacts, sprayed wiring harness connections with deoxit.

Tim used remote starter to get to the timing mark, to set timing later.  Checked TCS cleaned contacts, found AFM broken, installed a used one, cleaned contacts, set the timing.

10/27/15  RB blew white smoke.

10/28/15  RB died, would not start, towed home.  First incident.

11/1/15  pulled and photoed spark plugs, swipe in exhaust, all black carbon.  Posted photos on CZCC.

Installed new/old ECU.

RB odometer:

4/16   Oil change   96,634

1/17  Now               99,489

Driven on oil for 9 mo.- 2,855 mi.

Hope this is not overkill.  Wanted all to know what has happened to her.  How long before a full tune up is needed?  Miles or time?   8/15 - 1/17 =17 months

Thanks,

Jai