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My 1978 280z is Running Poorly Looking for Repair Shop In Florida to Fix It


furypilot

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My 1978 280z that I have owned for over 20 years and was the reliable car I have ever owned. About two years ago it started giving me problems. It would stop for no apparent reason like the key was turned off and would not restart for about 20 to 30 minutes then I would run fine. It turned out the ECU by the drivers left leg was bad. I replaced it and the problem went away. It would run fine and occasionally it would run rough and stop. Some times it will run great and the next time I try to start it it runs very rough and smokes white smoke and will not run over 1200 rpm. The next time I start it it runs fine. The last two times I drove it I ended up having to call a wrecker to get me home. I have done the following to ty to fix the problem:

Drained the fuel tank-it was fine
Replaced the fuel filter
Replaced the fuel pump
Replaced all the relays under the black metal box by the battery.
Replaced the relay by the glove compartment
New plugs
Replaced the ECU
Cleaned all electrical connections

None of these attempts seemed to help except changing the ECU. I have brought it to the best foreign repair place in town and they got it to run better but sometimes it just stops or runs poorly. I have purchased a reworked air control unit and coolant temp sensor and plug but haven't replaced them yet. I recently had to have a back fusion and can't bend for about six more months. I live in Vero Beach and there are no locals shops with experience with Z cars the age of mine. Can anyone recommend a shop in central Florida that could fix my car? Any suggestions will be appreciated.

Regards

Curt

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Was the ECU replacement new or just a different old one?  The symptoms do fit a bad ECU. 

 

But a bad ignition module is also a possibility.  If the tachometer needle is showing high RPM when you know it's low that is a sign of a bad ignition module.  The ECU opens the injectors for every third ignition pulse.  So it's dumping too much fuel because the ignition module is creating too many sparks.  SteveJ can do a module swap if appropriate.  And, banging on the ECU is the old ECU testing method.

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Sometimes it smokes and some times it doesn't. The water and anti freeze looks fine The tach needle moves up and down as the engine speeds and slows down rhythmically. The tach does not seems high. I replaced the AFM yesterday and checked the plug that might have 10 miles on them. Very sooty black and dripping with fuel. I replaced them and checked the spark as Yarb suggested and would sort of run for 2 to 3 seconds. The spark looks great and the plugs are dripping with fuel.  Yarb is sending me a ignition module to try next. 

Thanks

Curt

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On 4/16/2023 at 11:33 AM, furypilot said:

best foreign repair place in town

Did these pros run through the tests in the EFI Book by Nissan?  Easy to do and you might find something.  Might be you just have a bad connection at the coolant temperature sensor.  You can sit on the ground and reach in to get to the connector.  Hardest part is getting the kick panel plastic off.

You didn't answer the question about the age of the replacement ECU.  If the failures are due to age of parts then all of the parts are the same age so have the same odds of failing.

p.s. I've found that piece of solid core copper wire, flattened, works well to get in to the connector pins.  They're tight.

 

Edited by Zed Head
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The ECU replacement is bought from Z Specialties about a year ago. The local sop that installed it said that they could get the engine to die by tapping on the old ECW. The new or rebuild replacement stopped that from happening. The local stop did not have the Fuel Injection Bible, I now have a copy of it. Thank you for sending it to me. I cleaned the coolant temperature connections with a contact cleaning kit and it made no difference. I bought a new coolant probe and plug and will install it tomorrow. What kick plate are you talking about?  What contact pins are you talking about? The ones in the sensor? Thank you very much for your post I appreciate your help.,

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Sitting in the driver's seat the plastic panel would be directly left of your left knee.  It has a rectangular hole in it that allows you to see the tag on the ECU.  There are two or three screws holding it, one of them does not need to be removed all of the way.

Borrowed this from the BAT 8000 mile Z.

image.png

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I thought the coolant temperature sensor was the one that screws into the block close to where the upper radiator hose attaches to the block. Is the coolant temperature probe you are talking about part of large plug that plugs into the ECU? Thanks!

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I am not implying that you should buy a reman computer but I just wandered across this on the internet.  Apparently somebody is producing remanufactured ECU's.  In "reman world" that could mean anything from all parts that degrade over time have been replaced to all parts have been tested and left in place if they worked.

If you bought an ECU from ZSpecialties it was almost certainly a used one.  Oliver has a huge collection of used Z's and Z parts, apparently.

Anyway here is that link, just for future reference.  Do lots of testing first.

https://www.autozone.com/engine-management/engine-control-computer/p/bse-engine-control-computer-ecc1450/53480_0_0

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