300zx Loss of power

Discussion in 'Z32 Technical' started by joseph, Sep 10, 2018.

  1. joseph

    joseph Member

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    hey guys I’ve got a ‘92 300zx NA Auto I recently put a new engine,trans and tail shaft in started up an sounds fine I reved it and it’s got no misfire it’s got a really good responsive throttle though when I hoped in the car put it in reverse the car felt like it wanted to stall I took it for a drive and it was shaking really bad I felt like it was misfiring it had no power so I pull over to see if I was misfiring but It wasn’t I was thinking it was fuel cause the fuel in the car is about a year or so old it’s almost on empty but does any have any idea what it could be ?
     
  2. East Coast Z

    East Coast Z Well-Known Member

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    If it's a 2.0 seater, you can drain the fuel tank via the drain plugs in the bottom of the tank.
    Not sure if 2+2's are fitted with the drain plugs.
    Quarter fill it with fresh 98 & put your fuel related theory to the test.
    Don't fill the tank as you may need to change the fuel pump if it proves to be the problem.

    Have you checked for fault codes?
     
  3. joseph

    joseph Member

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    Hey yes it’s a 2 seater I’ll was going to drop the fuel tomorrow to give it a shot,I scan the car and it came back with no faults
     
  4. East Coast Z

    East Coast Z Well-Known Member

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    While you're focusing on the fuel system, perhaps a fuel pressure test could be worth considering.
     
  5. Gunwarm

    Gunwarm Kamikazee Special Corps

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    BP 98 is good for 12 months. They say that not me. But they are right as I have done that test.
     
  6. IB

    IB ?????

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    Have you checked for vacuum leaks?
     
  7. Martin Williams

    Martin Williams Active Member

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    TPS, AFM or FPU. Is it running rich? Have you done the timing? Whats the history on the replacement engine?
     
  8. joseph

    joseph Member

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    I think it has carltex e10 in
     
  9. joseph

    joseph Member

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    I’ve checked and there’s no vacuum leaks
     
  10. joseph

    joseph Member

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    I’ll check them as soon as I can, I haven’t touched the timing the history on the engine all I know it it has good compression and it’s on 79xxxxk
     
  11. joseph

    joseph Member

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    I checked the fuel pressure and that was all good
     
  12. East Coast Z

    East Coast Z Well-Known Member

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    So, where are we up to with this issue?
    Have you drained the fuel tank & refilled it?
     
  13. joseph

    joseph Member

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    So I just drained the fuel out and put 98 power in it but it’s still has the same issue,I made sure there isn’t a misfire by pull the coil pack connectors one by one to see if anything changes the car seemed to run worse with each coil pack connector I took off.
     
  14. DazzaZ32

    DazzaZ32 Active Member

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    Maybe the IAC valve ??? As its not compensating for it being in gear??
     
  15. Martin Williams

    Martin Williams Active Member

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    Did you replace the timing belt? I would have thought so as you have no history on replacement engine or when or if belt has ever been replaced. pretty simple when engine is out. If you did, did you fit new one correctly? If you didn't perhaps you have jumped a tooth or two!!
    What reading are you getting from TPS and AFM?
    Is the engine running rich when hot?
    What is the timing setting on engine.
    Did you buy ECU with engine? If not maybe the replacement engine has been modified ( ie. larger injectors than standard) and your ECU does not match this engine. The issue here is that in the past 20yrs or so most owners of 300ZX TT are not satisfied with the power Nissan provided and have therefore modified them, for better or worse. You probably have no idea the history of the engine or how long it has been laying around or how it was running.

    Just a few things to think about. Sorry to sound a bit negative, but I have had over a dozen of these beauties and have come across a lot of problems. Keep feeding us data, this forum has been great to me, there is a huge amount of knowledge and know how here and it is shared freely.
     
  16. J3bba

    J3bba He Who Struggles

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    Is it the trans maybe? If it runs fine and has good response at idle out of gear then maybe the trans is issue.
     
  17. East Coast Z

    East Coast Z Well-Known Member

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    Joseph, the boys are attempting to assist with your issue, however you are not providing any details.
    It looks like your theory relating to stale fuel has been disproved.
    Have you checked for logged fault codes?
    Did you check & clean the engine harness wiring & connectors during the engine replacement.
    You mentioned engine compression, what are the numbers?
    Have you checked the spark plugs for indications of what is happening in the combustion chambers?
    Were the injectors serviced?
     
  18. joseph

    joseph Member

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    Hey guys,sir I was having troubling getting in to my aus300zx account but I’m back now I’ve checked to see if the injectors and and all the engine wiring was working it’s was all good I’ve checked for fault codes but there was none the trans is really smooth and I got it from a family memeber who was converting to a manual the auto box was working perfect I’m going to try cleaning the maf and see if the crank angle sensor and tps is all set correctly first thing Monday
     
  19. Martin Williams

    Martin Williams Active Member

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    While you are checking everything check the FPU is working. ie. Fuel pressure under load. You say engine idles well but starts to misfire/miss under load. FPU maintains fuel pressure by varying fuel pump speed. You can bypass FPU, procedure is in Tech section, real easy. This allows fuel pump to operate at full speed at all times. You may have more than one problem!!
     

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