jzx90 mx83 running in limp mode.

[chaserbuddy]

hey all,

Need help finding the problem causing the car to run in limp mode. Just finished the swap.
Engine was running ok with a microtech few weeks ago and has been swapped to a re-pinned jzx81 ecu to suit jzx90.

Throws error code 2, 1, 4, 7. I assume this means 21 and 47? since i can not find a code listed for 47 it must mean 4 and 7?

So far ignitor has been checked, plus all the wiring for the ignitor. map sensor and wiring for map sensor. tps sensor and wiring has been checked. ecu has been swapped over.

I am not too sure about the NSW at the moment but it starts in Park and Neutral and not in any other gear. The voltages across NSW and STA wires are 0 volt when in Park and Neutral and 9.5 volt in any other gear, the car runs perfectly at idle but when driven breaks down under load. shifts ok. speedo works.

Also It's running a 7m gearbox loom and selector control. The lock up clutch has been added into the loom traced from another car and matched accordingly. O/D works.

The only thing i can think of is that the 7m gbox loom is not compatible with the jzx90 ecu as I have read somewhere that NSW and STA should have 9.5 volt when in P & N and 0volt when in any other gear? since this is opposite of what it is currently doing thus causing ecu to think its in park when its in drive?

If anyone has any information that would help please let me know.

Thank you

[JP]

STA should only have 12V when the barrel is in the start position

[chaserbuddy]

thanks jp. I think that's the case at the moment as I have the sta running to a relay as the trigger and it starts. will check the voltages across sta and nsw when running.

checked the codes again last night. only got code 47. I have found some error codes listed for an SC400 which was sub-tps. VTA2 exceeds 1.5v for 0.5 second or more. I don't know if this compares to jzx90 but its more then i found before

since there is continuity between VCC +5V to map sensor and VTA2 i assume this would be causing the code.




error codes to cause limp mode


from:
http://soarercentral.com/sc-forum/me.../1113/862.html

[chaserbuddy]

well all the codes have been eliminated. Still runs in limp mode though... :S really getting annoying now. I have checked all the sensors, voltage between ect and e1. 0-8v when throttle pressed and goes to 0volt when brakes are pressed. I think I still have a problem with the neutral start switch still. does anyone have a guide for wiring them up or some wiring diagrams, Also can someone explain why a jzx90 converted mx83 needs a relay to trigger the power to the starter motor and not just connect the wires directly from the mx83 body plug.

[JP]

you dont need a relay to trigger the starter, you can wire it exactly how the mx83 was and it will start just fine if the contacts in the starter aren't totally worn away.

[midnight_purple_GA70]

you need to make sure that the starter runs via the original jzx90 loom
so it would come from under the dash then go into the gearbox P/N switch (2 thickest wires on selector switch) and then out to the starter solenoid...
since you have a different gearbox in make sure this is followed somewhat (for safety)

you will then most likely need to ground the ecu STA wire

[chaserbuddy]

OK so the jzx90 has thinner wires to the NSW and one thick wire going from the ecu side to the starter I guess people use relays because the jzx90 NSW isn't designed for carrying high current as the mx83/jzx81? Can I ask why the sta to the ecu will have to be grounded?

[midnight_purple_GA70]

Yes, that's true when starting the engine.

But I suspect the main function of the NSW engine ECU pin is for when the engine is running - not starting the engine.

i.e. In the below images (taken from my wiki link above) you can see that I've 'greyed' out the power from the IGN switch as when the engine is running is doesn't play a part




Cheers
Wilbo

see these diagrams... should follow a path much the same... when the car is running STA wire gets a ground signal i believe...

if you dont have factory loom in place it doesnt get the ground signal and commences limp mode

as you can also see the ecu wires are just spliced in hence not needing to be as big

[chaserbuddy]

I have wired it up like the diagram above except instead of STA going to a relay it goes straight into the starter motor.
Voltages measured at ecu STA and NSW:

STA in any gear has continuity between ground.

with Ignition on(engine running or not same result):
NSW ~+12v in Reverse, Drive etc.
NSW 0 volt in Park/Neutral.

When cranking 0 volt between NSW and STA.

Are these the correct voltages?
If not i guess the 7M NSW on the gbox is different to the jzx90 NSW and needs to be changed.

[midnight_purple_GA70]

personally ide be chopping sta off on the ecu end and grounding it

then running a starter relay via the selector switch on the gearbox

[chaserbuddy]

ill give that a shot. what should i do about the nsw wire to the ecu. chop and connect to the 22pin body plug NSW pin? just checked the jzx90 selector does switch the same as a 7m one.

[midnight_purple_GA70]

leave it as is 1st then see what happens...

the conversion i did used jzz30 soarer 1jz with loom ecu and a340 into an a70

all i did was connected the cranking wire from the ignition barrel to the wire that runs to the selector switch (park/neutral) then the other side of that went to the starter solenoid
i then had it running like that but it would break down at about 4000-4500 rpm

chopped and grounded STA wire and it ran like a dream

didnt touch NSW wire to the ecu i dont think

[chaserbuddy]

seems to start a lot better but that's the only improvement, starts in Park and neutral still. The ecu is still not showing any errors in the system so I really don't know.

[midnight_purple_GA70]

if its starting in park and neutral the starter wire isnt following the right path...

IG barrel STA>gearbox selector switch (one side of the 2 thick wires on it)>starter solenoid

try get that sorted 1st

[chaserbuddy]

this is how i have it wired at the moment.