1jz vvti hesitation coming on boost code 55?

Thread in 'Technical Questions' started by Ross 27, Oct 26, 2018.

  1. Ross 27

    Ross 27 Member

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    Right guys after some help I have recently got my 1jz vvti 350z on the road it ran spot on for about 600 miles but I'm now having issues. When the car starts coming on boost around 2500 rpm the car holds back and splutters after this it will go but not as quick as before it happened once and i reset the ecu and it was fine again but now it's back and won't go away. The car is flashing up code 55 on the jzx100 ecu I believe this is rear knock sensor so I have replaced that and it's made no difference any help would be great I'm hoping it's not knocking as it was a low mileage import engine from jdm garage thanks Ross
     
  2. Ross 27

    Ross 27 Member

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    Anyone struggling with this
     
  3. beat_core

    beat_core Member

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    If you're sure it's the knock sensor and you've swapped it, have you tested the wiring loom from Knock Sensor end to ECU end, to make sure Loom is OK?
     
  4. Ross 27

    Ross 27 Member

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    Yes I have tested the wires and they were fine the whole loom was new around 3 months ago from wiring specialists to be honest I'm not 100 percent it's the knock sensor as no one seems to know what code 55 means. I realised at the weekend it boosts when cold I know not a god idea but I wanted to see if it did to help the process of elimination a few people have suggested this could mean the coil packs are knackered so I may try this next?
     
  5. orange_beastie

    orange_beastie Pickup driftin

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    Check the spark plugs aswel as too much boost can cause poor sparks so if the coils are going then most probably need/want new spark plugs. Could be bad earth between coils and head.
     
  6. Ross 27

    Ross 27 Member

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    New spark plugs on order do the coils earth through the bolts that hold them in? Also what should I be gapping the plugs to as I've seen several different figures thanks for the help Ross
     
  7. orange_beastie

    orange_beastie Pickup driftin

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    Yep the bolts should all be tight spray some wd40 over them and the holes before you do them up plug gaps should be fine on new plugs 0.8mm anything over 12psi should go for .7
     
  8. Ross 27

    Ross 27 Member

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    Cheers but replaced the coil packs and plugs all bolts tight and it's exactly the same beginning to give up hoping it's not actually knocking but the the code keeps flashing up and I'm a bit lost as to what to try next
     
  9. orange_beastie

    orange_beastie Pickup driftin

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    If its not spark then could be a fuelling issue?
    Have you done a compression test to rule out piston rings?
    If its a fuel problem could be fuel pump power being interupted or injectors not firing properly, if u use a metal bar and touch the top of each injector you should hear them clicking. If there all working fine.
    The afm can cause issues but the engine wont normally rev over 2500rpm.
    Check the turbo to make sure the wastegate is closing fully could be leaking off under high pressure. Check with your boost gauge to see if you can get and hold boost.
    If your getting a knock code at the back its generally mixture is to lean which is either to much boost or not enough fuel.
    Sorry for the mixed reply just all i can think of right now.
     
  10. Ross 27

    Ross 27 Member

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    That's ok any reply are very helpful the fuel pump is fairly new so should be fine I think your right probably worth investigating the fuel side I have a spare afm I can try I had Considered the ignitor could have broken down it seems to boost fine and hold boost when it goes I will check the injectors as you said I just can't make out why it only does it once its warmed up
     
  11. orange_beastie

    orange_beastie Pickup driftin

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    When its warm should go into closed or open loop mode on ecu so uses o2 sensor to adjust could possibly be that causing it to give less fuel ? Have you tryied testing it with a multi meter?
     
  12. Ross 27

    Ross 27 Member

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    No I will give that a go looking at it it does look a bit bent so it could be a bit dodgy thanks for the help I'll look up the parameters for the sensor
     
  13. Murf

    Murf Member

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    If it's throwing a code up then you need to get to the bottom of it... OBD1 is cool but can be very unspecific. Did the wiring guy not wire in OBD2? It's only a few extra wires and the codes you get from OBD2 are a lot more specific and help you getting to the bottom of the problem better than OBD1.
     
  14. Ross 27

    Ross 27 Member

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    Not sure if its obd1 one or two to be honest I will speak to wiring specialists new o2 sensor made no difference car seems to missing on idle now and problem seems to have got worse
     

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