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Discussion Starter #1
so i bought a 1983 280zx turbo for 200$ and it sat for 14 years before i got it. ive replaced the fuel pump, injectors, most vacuum lines, spark plugs and wires, distributor cap and rotor, brake master cylinder, slave cylinder, clutch master cylinder and it runs and drives okish. between 2800-3200 rpm it has a real rough spot where it struggles to contine reving. my dad says its just the turbo having bad bearings or at least clogged ones because we took it out and it spun freely and felt like a almost 40 year old turbo. the car also has a issue with starting because it floods itself. could this be because the car isint sucking as much air as it should be and the computer is sending the correct amount of fuel as if the turbo was spinning as fast as it should be and drawing the correct amount of air? i have no idea and if i cant fix these problems im gonna have to let the car go and i really dont want to do that so any suggestions on how to fix it or whats wrong that i dont know about?
 

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That's the "cruise" RPM range and your symptoms echo what many other owners have faced. It's most likely worn carbon traces in the AFM. Way back in threads here and on Hybridz you could find info on the problem and how others have dealt with it. But, eventually, we all move past the stock EFI (ECCS) system and to a different ECU and air-metering system.

Besides the AFM, I've found that 90% of problems with the ECCS system is wiring and connectors. The stock harness is not weathertight and both connectors and wiring oxidize over the years. These cars weren't designed to last this long. Poor connections play havoc in an EFI system. The ECU is working off data it's getting from the sensors and if the wire and connectors are corroded, the data will be skewed or non-existent. Your CAS, Cylinder Head Temperature Sensor, and AFM are the three most critical sensors.

What does a 40 year old turbo feel like?? If it spins feely and the shaft has very little movement fore-to-aft and side-to-side it's in good enough shape. You're probably looking at something that isn't really a problem. Turbochargers were designed to work in piston aircraft so they have to be very simple and VERY reliable.
 

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Discussion Starter #3
That's the "cruise" RPM range and your symptoms echo what many other owners have faced. It's most likely worn carbon traces in the AFM. Way back in threads here and on Hybridz you could find info on the problem and how others have dealt with it. But, eventually, we all move past the stock EFI (ECCS) system and to a different ECU and air-metering system.

Besides the AFM, I've found that 90% of problems with the ECCS system is wiring and connectors. The stock harness is not weathertight and both connectors and wiring oxidize over the years. These cars weren't designed to last this long. Poor connections play havoc in an EFI system. The ECU is working off data it's getting from the sensors and if the wire and connectors are corroded, the data will be skewed or non-existent. Your CAS, Cylinder Head Temperature Sensor, and AFM are the three most critical sensors.

What does a 40 year old turbo feel like?? If it spins feely and the shaft has very little movement fore-to-aft and side-to-side it's in good enough shape. You're probably looking at something that isn't really a problem. Turbochargers were designed to work in piston aircraft so they have to be very simple and VERY reliable.
I was thinking was someting simple like that but i didnt know exactly what so this will help a ton and it feels like a used turbo except it feels like it has too much resistance when spinning it (everything else feels good) but i also dont have a ton of money because this is my first car and im going to buy a car to daily while i do what i really want to do to this car but thanks for the info! :)
 

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One good idea would be to hit all the electrical connections with Caig DeOxit and make sure they're as clean as possible. The part that matters on the turbo is to have NO lateral movement on the shaft. If it moves side to side in the housing it's rebuild time. Hopefully you're OK, and if it's boosting and not rattling I would say you are fine.

Incidentally, my 83 ZXT is stock ignition and working fine. I agree the connectors can get oxidized, but you can usually clean them with DeOxit an a Q-tip.
 

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Discussion Starter #5
One good idea would be to hit all the electrical connections with Caig DeOxit and make sure they're as clean as possible. The part that matters on the turbo is to have NO lateral movement on the shaft. If it moves side to side in the housing it's rebuild time. Hopefully you're OK, and if it's boosting and not rattling I would say you are fine.

Incidentally, my 83 ZXT is stock ignition and working fine. I agree the connectors can get oxidized, but you can usually clean them with DeOxit an a Q-tip.
Mine would be fine but it sat undisturbed for 14 years until i bought it and a sister car to flip and i plan to do that now that my knowledge has vastly expanded on this 37 year old turd and thanks for the advice! :)
 

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If you do get it running, here's critical information about the turbo:

  • NEVER shut the engine down suddenly after you have been driving it. Always idle it for at least 10-30 seconds first, even if you have been driving at city speeds. Reason: the turbo is spinning fast when it's boosting, and it takes time to slow down. When you turn off the engine the oil pressure goes away. The turbo is then spinning on its bushings with no oil pressure. Don't let this happen.
  • If you have been highway driving, DO NOT pull over and turn the engine off. Idle it down for a minimum of one minute, and 2-3 minutes is better. Reasons: first, that turbo is not water cooled; it's only oil cooled. Highway speed driving will probably have that turbo nearly red-hot, especially if you've been using the turbo frequently. Cooling the turbo down by idling it reduces the chance of oil cooking onto the bushings from heat. Second, the same concern about the turbo still spinning when oil pressure drops as in #1 applies.
  • Run ONLY top quality synthetic oil. Reason: synthetics have a higher coking point, meaning that they are less likely to burn onto the bushings when the turbo is hot. Synthetics also persist better on lubricated parts, which is directly beneficial to turbo bushings. Your engine in general will last better with synthetic oil, and the turbo in particular will benefit. I refuse to use anything but synthetic oil in turbo cars, and that has been my practice since 1977.
Remember, by today's standards that turbo is primitive. It's only oil cooled, and has no water cooling passages as many newer turbos do. Also, remember that these turbos don't have bearings, they have bushings to house the spinning turbo shaft. This means the more you can do to keep those bushings in good shape, thee better you are.

Story follows:

I bought my 1983 280ZX Turbo in 1990 with 49K miles. The previous owner knew nothing about taking care of turbos. In 1992 at 54k miles, the turbo bushings were shot, it was rattling like a garbage disposal full of spoons, and I had it rebuilt.

Clearly, the previous owner had destroyed the turbo by not taking care of it.

Using the care principles I outlined above, the problem has not repeated. In 2020 I have 130K miles using that turbo, and it is in good shape and has not needed another rebuild. During this period, in addition to using it as a daily driver and as a "fun car," I have autocrossed the car, driven it a few laps on a NASCAR track, and run laps at Second Creek Raceway in the Denver area. I think this experience shows that I'm on the right track taking care of that turbo.
 

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Discussion Starter #7
If you do get it running, here's critical information about the turbo:

  • NEVER shut the engine down suddenly after you have been driving it. Always idle it for at least 10-30 seconds first, even if you have been driving at city speeds. Reason: the turbo is spinning fast when it's boosting, and it takes time to slow down. When you turn off the engine the oil pressure goes away. The turbo is then spinning on its bushings with no oil pressure. Don't let this happen.
  • If you have been highway driving, DO NOT pull over and turn the engine off. Idle it down for a minimum of one minute, and 2-3 minutes is better. Reasons: first, that turbo is not water cooled; it's only oil cooled. Highway speed driving will probably have that turbo nearly red-hot, especially if you've been using the turbo frequently. Cooling the turbo down by idling it reduces the chance of oil cooking onto the bushings from heat. Second, the same concern about the turbo still spinning when oil pressure drops as in #1 applies.
  • Run ONLY top quality synthetic oil. Reason: synthetics have a higher coking point, meaning that they are less likely to burn onto the bushings when the turbo is hot. Synthetics also persist better on lubricated parts, which is directly beneficial to turbo bushings. Your engine in general will last better with synthetic oil, and the turbo in particular will benefit. I refuse to use anything but synthetic oil in turbo cars, and that has been my practice since 1977.
Remember, by today's standards that turbo is primitive. It's only oil cooled, and has no water cooling passages as many newer turbos do. Also, remember that these turbos don't have bearings, they have bushings to house the spinning turbo shaft. This means the more you can do to keep those bushings in good shape, thee better you are.

Story follows:

I bought my 1983 280ZX Turbo in 1990 with 49K miles. The previous owner knew nothing about taking care of turbos. In 1992 at 54k miles, the turbo bushings were shot, it was rattling like a garbage disposal full of spoons, and I had it rebuilt.

Clearly, the previous owner had destroyed the turbo by not taking care of it.

Using the care principles I outlined above, the problem has not repeated. In 2020 I have 130K miles using that turbo, and it is in good shape and has not needed another rebuild. During this period, in addition to using it as a daily driver and as a "fun car," I have autocrossed the car, driven it a few laps on a NASCAR track, and run laps at Second Creek Raceway in the Denver area. I think this experience shows that I'm on the right track taking care of that turbo.
Its not been on the road yet, we have only putted it around our property a few times to clean out the exhaust as creatures have made homes in it. The previous owner daily drove the car and had taken care of it because i found reciepts for routine maintenance at a local shop since 1986, it does have 177000 miles and i do plan on rebuilding the motor in the future but time and money does not allow this until probably 2022-3 after i graduate from uti but im going to be a seinor next year. We did put high grade synthetic oil in it, ran it for a few months and changed it to make sure it was good oil in it and to check for metal shavings and there were none. Its just going to be a fun car for a few years until i can get it to the point i want(400-450ish hp) but im going to take my time and do it right. Thanks for the advice, its greatly appreciated! :)
 

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One good idea would be to hit all the electrical connections with Caig DeOxit and make sure they're as clean as possible. The part that matters on the turbo is to have NO lateral movement on the shaft. If it moves side to side in the housing it's rebuild time. Hopefully you're OK, and if it's boosting and not rattling I would say you are fine.

Incidentally, my 83 ZXT is stock ignition and working fine. I agree the connectors can get oxidized, but you can usually clean them with DeOxit an a Q-tip.
Are you running stock lifters?
 

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Discussion Starter #11
Me too. My 83 ZXT is all stock except for the radio and power antenna.
Same, im going to put a better radio and speakers in the car if i keep it. I have someone who might buy it for 3k and if they do, im going to buy a is300 for 3500 thats already runing and driving. I dont want to sell it but im probably going to have to.
 
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