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Discussion Starter · #1 · (Edited by Moderator)
1975 280z auto fuel injected

Misfire video??

Alright, my car was running into issues starting I just replaced my starter and now it’s starting up like a charm! However now I’m on to a new problem. when the car idles it sounds like is a little sputtery in the exhaust

but the main issue is the second there is load on the car under 25mph I’m hearing popping coming from the engine.

It sounds like maybe a misfire. I placed my hand in front of my air intake and I can feel it sucking in air until it pops then I can feel air push out. Then it goes back to sucking in air. the second I get over 25mph it stops. So I can drive at highway speeds or normal speeds around town. But if i come to a red light or a stop sign the pops start again under load while driving until 25mph then it stops again.

i just replaced the fuel filter and it seems to be running better over all but the popping is still there.

I replaced one fuel injector back in the day but I don’t know if this could be a possible problem. I pulled all of my distributor caps off and noticed each one caused a noticeable difference in performance so I don’t think it’s a bad spark plug.

So I’m at a loss atm and I don’t want to go spending 100’s replacing everything fuel related just to figure out I’m wrong lol.
 

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1983 280ZX Turbo
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You need to view the codes in order to know anything meaningful. It sounds like a misfire, but whether it's a coil or spark plug is unknown.

Start with the codes. If it's specific to one cylinder you can swap the coil with an adjacent cylinder and see if the misfire moves. If so, it's the coil.
 

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Discussion Starter · #4 ·
If air is pushing out of your air filter I'm guessing intake valves are still open when the cylinder fires, maybe your timing is off?
what would have caused the time to randomly change? Everything’s has been fine since I had had my Head gasket replaced and the car timed afterwards.

I haven’t done any change’s mechanically
 

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You need to view the codes in order to know anything meaningful. It sounds like a misfire, but whether it's a coil or spark plug is unknown.

Start with the codes. If it's specific to one cylinder you can swap the coil with an adjacent cylinder and see if the misfire moves. If so, it's the coil.
I think those diagnostics would work better with a 350Z or 370Z than a 75.
 

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1983 280ZX Turbo
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I think those diagnostics would work better with a 350Z or 370Z than a 75.
Dangit, I moderate two forums and forgot which one I was on!!!! DUH!

Sounds like a misfire to me. Check the plugs to see if any are off-color, and if you haven't replaced cap and rotor this might be something to consider.

While you have the cap off, wiggle the distributor shaft and make sure there's no side-to-side play. The bushings can get worn, letting the shaft travel erraticly.
 

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1981 280zx GL na 5spd
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what would have caused the time to randomly change? Everything’s has been fine since I had had my Head gasket replaced and the car timed afterwards.

I haven’t done any change’s mechanically
I think a faulty vacuum advance can cause misfire/overheating, it could cause the cylinders to fire before they hit TDC. There's videos on how to test your vacuum advance
 

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Lots of things can cause this. Start with IDing which cylinder is misfiring. With the engine running remove one spark plug wire at a time from the distributor cap and see if the engine changes. When the engine doesn't change that is the bad boy and go from there. Lots of good suggestions so far. You may want to check your valve lash also. Compression test would be good also
 
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