300zx Loss of power

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

  1. ADAMZX

    ADAMZX 2000spec Conversion

    i think the first step in diagnosing your problem is to maybe service the transmission with new fluid and filter. inspect the tailshaft and then maybe test the coil packs and injectors to make sure they are in spec. a conzult check to look for error codes.
     
  2. Martin Williams

    Martin Williams Well-Known Member

    Please give us feedback on all our suggestions. Have you bypassed the FPU, I believe this is your issue. Measure your fuel pressure in idle and then under load. Very unlikely to be gearbox or tailshaft. Whats your idle RPM in P or N? Whats your idle speed in gear? Whats your TPS and MAF reading? Where do you live?
     
  3. joseph

    joseph Member

    Hey Adam the transmissions got brand new fluid and filter changed about 1 week ago,I haven’t inspected the tailshaft yet but the coil packs are good I don’t know about the injectors or the fault codes though
     
  4. joseph

    joseph Member

    Hey I haven’t tested the FPU as I don’t have the tool to test it I think the TPS AND MAF are good I’ll double check,the idle in Park is about 900-800rpm I’m not sure what it is in gear I’ve got a video but it’s not letting me upload it I live in broadmeadows
     
  5. rob260

    rob260 Administrator Staff Member

    Have you checked the ignition timing as @Martin Williams suggested? As your car is fit with an automatic transmission the base timing should advance when in driven gears, perhaps this is not occurring or timing is incorrectly set...?
     
  6. East Coast Z

    East Coast Z Well-Known Member

    Here's your problem Joseph.................
    This mechanic is stuffing you around.
    He probably realises the engine requires work, which will take a significant amount of time on his part & a lot of dollars on your part.
    What is "grey fixing" something?
    Never heard of it.
    You either fix something properly, or you don't, it's that simple.

    It is NOT normal for a normally aspirated VG30DE engine to run like shit in Neutral or Park.

    In Neutral, with the engine at operating temperature, the engine should idle at 770 RPM plus or minus 50 RPM.
    This means if your engine is idling between 720 RPM minimum, up to 820 RPM maximum, the idle speed is correct.
    But it should be smooth, it should not run rough.
    When you put the transmission in Drive, you would expect to see the idle speed to drop from the above speeds.

    You've indicated the engine compression was checked & was good in a previous post.
    I asked what the numbers were, however you have neglected to answer.

    I'll tell you something about that engine without even seeing it.
    There is no way that engine has only done 79 something thousand kilometres, even though you indicated 790 thousand in your post.

    You need to go back to stage No.1 & that is compression test the engine at operating temperature.
    The compression should be between 186 & 142PSI.
    If it has less than 142PSI, the engine has had it.

    If the compression tests OK & I hope it does for your sake, then you need to determine if the misfiring is related to spark or fuel.

    10 seconds from 0 to 60kM/h.
    Really?

    Did the mechanic supply the replacement engine?
    If he did, then you have recourse under Australian Consumer Law.
    If you supplied the engine & he fitted it, then you're up Shit Creek without a paddle.
     
  7. joseph

    joseph Member

    I told the mechanic that I thought it was timing but the he only said he would have a look into it
     
  8. joseph

    joseph Member

    Yeah I realise his stuffing me around I’ve gave him till Sunday to fix the car car completely or I’m taking it back,I didn’t realise you ask for th compression number due to trying to reply to everyone as fast as I can the numbers were between 175 to 164 in all cylinders,the 0-60kmh was actually that long that’s how slow it is he also did supply the engine and trasmission himself and the car in N or P runs perfect it’s just when your in a gear like Reverse or 1st 2nd and Drive I told him that it was not normal to be running that bad why in gear but he just told me to give him till Sunday
     
  9. DazzaZ32

    DazzaZ32 Active Member

    Ok you need to go buy a consult cable and a dongle or go to someone who has one as you will see if the timing is out when you stick it in gear.
    As East has said it is NOT normal for an NA to run shit in park or neutral.
    So something is causing it and if you keep going to a mechanic its going to cost more than the car.
    What area you live maybe someone has got consult to have a look for you.
    As if the engine was change im stating to think a vacume hose has been put on the wrong place.
     
  10. joseph

    joseph Member

    Hey guys,so I think I know what’s wrong with the car it’s coming up with a code 54 I thinks it’s a signal circuit to the transmission control unit,would anyone know why I’d be getting this code the ecu to the box is from my car which is for an auto so I don’t know why It would be doing it.
     
  11. rob260

    rob260 Administrator Staff Member

  12. joseph

    joseph Member

  13. pmac

    pmac Z,, IT'S COMPLICATED!!!!!

    Joseph, sounds like your really confused.
    You say
    "in N or P it revs fine no issues but once you put it into a gear it’s seems like it’s misfiring only when it’s in gear tho I think maybe cause it has no power and the car sounds like it’s misfiring it might be the trans or tailshaft.

    So is it misfiring or not? and what could that possibly have to do with the trans/tail shaft? That would have to be two separate issues?
    Check all your intake piping for leaks, loose clamps, splits etc. This has caught me out in the past and will cause an engine to "run like shit".
    Hope your mechanic can get his shit together and sort it out.
     
  14. joseph

    joseph Member

    It’s not misfiring while in gear I’ve checked and all the coils and injectors they are working I’m just saying it feels like it’s missing when it’s in Drive or 1st and 2nd I can only discribe it as a feeling like it’s missfire just so everyone can have an idea on how it’s running while in a gear,with the tail shaft I know a bad tail shaft can do all sorts of thing but I’ve checked for vacuum leak also tightened all the clamps to make sure some where abit loose but there was no change All I know is the mechanic said that there’s a code 54 that’s coming up that got to do with the transmission control unit so I think that’s the cause of the problem I’m having hence why I’m P and N the cars fine but when it’s in an actual gear it starts to play up
     
  15. ewschinzel

    ewschinzel Member

    This seems to go round and round, looks to me you don't know much about the replacement engine. A bit vague to say it feels like its miss firing, it either does or it does not, same goes for all other relative data like compression...tps settings and so on.
    Maybe you should find a different mechanic...its not brain surgery ( well almost) to run a diagnostic on an EFI engine...zx or not.
    Just for whats it worth...if the engine is in good shape , compression, oil pressure, timing , fuel supply ok, spark ok, vacuum leaks checked, whats left is the harness/electrical...which most likely is 28+years old...connectors need cleaning or replacing...all you can get at. ECU, CAS, MAF, coils, injectors, O2, knock, hot water, fuel temp, tps...and so on. U need a needle file, pick, contact cleaner, a good small torch and patience.
    Good luck
     
  16. DazzaZ32

    DazzaZ32 Active Member

    Well go and try another ECU and TCM with a known working one and if the issue still there, Start the process of elimination.
     

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