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I have a 1976 280z, Fuel Injected, of course. I have an intermitant problem with the car just dying. While I'm driving, the car just dies, tach drops to O. Sometimes I can just turn ignition switch and she'll start. Other times I have to give it a few minutes and she'll start.

1) It seems that she never starts until temp guage drops all the way down by switching the ignition off.

2) I did notice however that on one occasion when I got her started and got in the car slammed the door she died again.

This got me thinking that there may be a short in the FI, ECU. Additionally, sometimes she'll start and run a little rough. when this happens you can give a kick to the ECU and she'll either run smoooth or die. I've taken it to a couple of mechanics and they did not fix the proble. This problem is driving me *$%@ing crazy.


First would a loose wire or connection in the ECU cause the car to die like that. Second, Is there an easy way to test the ECU performance.

I really dont want to shell out $300 - $400 for an ECU if that isnt the problem. And I really dont want to bring it to Nissan and have someone trace wires at $75/hour unless a last resort

Ive already changed the Thermodyne switch and coil, pulled the ECU, cleaned and sprayed the connectors with CRC. Opened the ECU box to see if I could find any loose connectors, could'nt find a loose connection, problem still occuring.

Any help would be appreciated.

Thanks
Frank
 

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Frank-Your description sounds very much like a failing ignition module. Unfortuantely, I know of no way to test one; the failure pattern begins with the car suddenly dying for no obvious cause, runs great one second, the next the tach drops to zero and the car coasts to a stop. The car will not restart until the module cools or recycles (whatever it does). No amount of starter grinding will get as much as a sputter until the car decides to cooperate and will restart and run as though nothing was ever amiss.
Another clue is that after the car dies, if you try to restart, the tach needle doesn't even quiver.
the only cure I know of is replacement, perhaps you can borrow a working distributor/module from a buddy's running car and swap it in for a day or so to see if the problem goes away.
Dan
 

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Sounds like Ignition...

Just dropping dead sounds like dropping fire. Try to carry some "Freezit" stuff you spray on electronic circuits to test for thermal failures.
You need to drill a small hole in the distributor, and when it dies, leave the ign on.
Go out underthe hood and spray the freez-it into the distributor and then crank it. If it works, then you have a heat related-failure in the distributor (like the coil mentioned above).
If the ECU drops out while running, the fuel cuts off, so you should pay particular attention to the SMELL of the car after an unexpected shutoff.
If you smell raw gas, then it most definitely ignition related. If not, it MAY be the ECU, but if the ignition unit is failing, and the pulsed signal doesn't go back to the ECU, it won't fire the injectors, SOOOOOOOO
The injectors should fire every third ignition pulse, ignition can affect the ECU's operation, the ECU does not affectthe ignition (at least on a 77, that is...)
So your bets are better hedged on the ignition, unless you can do the swap mentioned above. Either way you have to isolate it to one circuit or the other. A spare distributor will someday come in handy if that's not it! :p
 

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Re: Sounds like Ignition...

Also might try wiggling the connector on the ECU while it's setting there idling and see if it cuts off. Possibly a loose connection in the back side of the ecu connector. Also the connector to the fuel pump/fuel injection relay is up in that same vicinity. Might want to make sure connections there are clean and tight. Same thing, wiggle the connector. BUT from the sounds of the tach immediately dropping it sounds more ignition related.
 
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