help me Wire up my 2jz....

[Guest Seedy Al]

hey guys

SO I am currently in the prcess of doing the wiring on my 2jzge engine in my crown.

basicly i am having to splice the original loom I had with the 2jz engine, mhich is from a crown, into a ECU from a JZA80 supra.

First question. ECU earths and sensor earths. Can I just bunch these all together and run one single wire? or should i spend a bit of time tracing out where they all run on the Supra loom and try replicate it with the crown loom?

Also, the starter wire that goes from the start side of the ignition switch, labled STA. I assume no matter what i have to run this?? I read that it uses 12v to the ecu while cranking, and then goes to earth via the starter relay. Does this mean I am also going to have to run the starter relay, or is there a easy way around it?

I have other questions, but will bring those up as I go, have done half the wires on the engine side so far.

thanks for any help guys

[Guest JoKer]

have always heard separate earth's are better ; common bad

[Guest Seedy Al]

yeah, I had some what heard this also.... was just wondering how essential haha

[Guest ta63-1uzze]

sensor earth go to the ecu and must be kept separate form all other earths. this is the air temp earth, cooling temp earth, cam sens earth, crank sens earth, oxygen sens earth ,basically all sensor earths go to the ecu. via the same wire, so sensors have a common earth. injectors and ignition have separate earth , they must be kept separate. also there will be shielding on the crank and cam sens. oxygen too they need to be shielded all the way up the the ecu. the shielding needs to be connected to the earth too . this is important , if you get some induction on these wires it can cause you allot of headaches and ghostly type faults and possibly damage your ecu. so shielding is very important .

ecu has its own earth that comes from the ecu and normally is terminated with a round soldered terminated that is bolted to the back of the head , some even have 2 earths that go to the block and the head. these are important and need to have good rust free connection

you can basically wire your engine how you would wire a aftermarket ecu. all the same rules apply .you could even use the link instructions as a guide , use there check list as your own checklist so you know that you haven't missed anything .

are you using the standard ecu?

[Guest Seedy Al]

yeah standard ECU.

The ECU pin out has 2 earths next to each other coming off it.

The loom with its sheilding is still present on mine, and have noticed they join up in a few palces.

Singlanl earths seem to go back to the ecu as you said and I will keep those the same

its mainly just the two earths coming from the ecu that i am interested about.

[Guest ta63-1uzze]

have a look on your engine, it may have a couple earth points or as i have found sometimes the 2 earth wires go to the one point anyway, typically on the back of the head. either way i wouldn't worry about which one is which as they both go to earth anyway , they may have the same or different mounting point to the engine either way it doesn't matter to much . as long as they are all connected

[Guest Seedy Al]

cool.

I am pretty sure they do just go to a bolt on the back of the head.

All the earths on that side seem to be connected to a lug that bolts on there anyway.

So soweet, I will wire the two earths out of the supra ecu to the brown wire that is on the crown plug and connect to loom.

thanks

any thoughts on the STA wiring?

this is the info i have.

This pin is used to determine if the engine is being cranked. The engine ECU can take action to allow the engine to start easier if it is aware that the engine is trying to be started.

Automatic transmission: This pin is connected to battery voltage when the ignition switch is in the CRANK position and the automatic transmission shifter is in the 'N' or 'P' positions. When the engine is not being cranked this pin is connected to Ground via the Starter Relay coil.

Manual transmission: This pin is connected to battery voltage when the ignition switch is in the CRANK position. When the engine is not being cranked this pin is connected to Ground via the Starter Relay coil.

i guess when you read that it makes sense to run it, Just means I have to wire up another relay.

the less is better haha

[Guest ta63-1uzze]

i would use that setup if that is how it is made to work , not hard to wire up .

it could be a ecu power control, used for opening and closing idle air control valve . , im not sure without looking at it to be honest . but auto or manual it asks for it so may as well.

[Guest Spencer]

It will start OK without the STA hooked up, but just tee 12v into it while cranking and it'll be sweet, wouldn't bother earthing it through a relay

As said run the earths how the factory intended or you end up with earthing loops from your senders

Funny you mention the idle control valve as its usually the number one thing that gets fucked up on this era of toyota wiring. Make sure you use the M-rel (Main relay) pin to power the relay that gives power to the idle control valve (and a bunch of other bits). If you wire this up properly the ECU keeps power to the idle control valve once you turn the key off to reset it back to a known position. If you fuck this up you end up with a hunting idle and no proper idle up

[Guest Seedy Al]

Yeah you have mentioned that beforwe and have had it in the back of my mind the whole time haha

but yeah have most the sensor control poweres crossed over now,

Was thinking of just conecting the sta to just run power. will see how it goes.

thanks guys for your help

[Guest ProZac]

Mitsy ECU's use the starter signal from the ignition switch to determine when to turn on the fuel pump, Don't know if toyota's are the same, but if your ECU is controlling the fuel pump relay, I'd hook that starter wire up.

[Guest nigelwade]

read alot of this,

M-REL is main relay, thats turned on by the ecu when it's started or running. it's an output, 12v+ bugger all amps, enough to switch a relay coil over.

- it's used too power the engine sensors and stuff like that.

Earths: the more the better, the higher the quality the better the engine runs.

I put two on every engine I work on. one either side of the block to the chassis.

Ecu earth to it's own earth point in cabin.

Sensor shielding to it's own earth point in cabin.

general sensor earth wires are normally on the head at the rear.

Often there is another relay called Circuit Open, in the diagram, and in the later model engines it's best to set that up.

STA is the power feed which tells the ecu it is being started so it's time to try to run. (over simplification). it takes 12v +

Re:fuel pump, yes they do control it the same way.

[Guest Seedy Al]

Well I cheacked out all the earths on both looms and they all just seemed to connect up to each other in different places anyway. So I have all my earths going to two factroy lugs that will bolt to the engine. Hopefully its enough to make it work.

Also freaked out at one point as I had all these spare wires of the same clour bunched up, then realised they are the power wires to be feed to the main relay. silly me!

Ok, I do have a question about fuel pump tho.

originally the Supra used a sperate ECu to control the fuel pump. So, how do you think I am best to run the fuel pump? Seeing as I belive for a cert the pump cant be running when you turn the key on or some such jazz????

Would i be able to run a spereate relay that is switched by the main relay? As I assume the main relay isnt doing anything until the engine it cranking?

Might just wire to iginiation anyway, as before Cert i may convert to link anyway.

[Guest Spencer]

HELLO SEEDY

The fuel pump controllers of the era are simply a 2 (or 3) speed controller for the pump, just keeps the pump quiet while you are cruising and probably gives it a longer life.

The engine ECU sends a PWM signal to the fuel pump controller and tells it to hurry up, this is over the FPC pin I think. You don't really have a setup like the old circuit opening relay so I would just wire a relay for the pump hard off the key for now, sort it properly later after nats. You would have to test the M-rel pin, pretty sure it won't do what you need, as far as I have tested it just holds power to the EFI gear after the key is off to reset the Idle stepper motor, no idea how it behaves if you stall? I imagine it stays on

[Guest Camel]

Or you could just use the original ECU that I was going to send you??

[Guest nigelwade]

Spencer is basically dead on the money there.

as per cert, unsure but; if you crash, your trapped in the car, out for the count, the fuel lines are broke, key on, engine not running, pump running fuel leaking at high volume; recipe for roasted driver and passengers. I would spend hours trying to prevent that situation being possible.

[Guest nigelwade]

one issue with EFI fuel systems is maintaining pressure.

- the the system leaks pressure after being shut down,

- the when the ecu turns the pump on it begins pumping

- this occurs at the point of cranking,

- the pump, cannot re-pressurise the entire system in time for the starting moment so the starting even falls over, with a cough and a splutter.

- but it will start it just fine the second time, quite quickly.

- the cause is the lines, rails, no longer have enough pressure (20-30psi at least) through a failure in the set up.

- one issue causing this is a bad regulator which leaks pressure over time, or a pump which 'back leaks pressure'

- or a poor set up, and mistake in it's design.

- making the engine hard to start.

The FPR pin is the correct pin for the fuel relay, although I have also found FPC sometimes works where FPR does not.

- basically you just need to set up the relay on either and use the pin as a switching current for the coil in the relay. for memory the output is a postive voltage.

- key: they come into play at the point of starting, so until you hook up STA and try to start (starter does not have to engage) you will not see activity on this.

- if you want to see if it will turn a coil over, hook an LED light up to it, if the led gets fried the voltage is high enough to switch a standard relay, if not, then no.

- some toyota ECU's send a square pattern signal down that line to control the fuel controller, it's a 5v signal, not enough to switch an ecu.

- there are fairly easily ways around that, using micro switches which are very cheap.

- you can make a little box with a basic circuit board in it, to take the 5v, and switch a mirco relay which then sends out 12v, to a a normal relay coil

[Guest Seedy Al]

I have a problem

For some reason, the mel-r wire is switching on when the igition is turned to run, instead of switching on when its being cranked.

As a result, when I turn the igition off, the vehicle keeps going and this wire is still out putting 12v, which is what it does to switch on the main relay.

Anyone have any idea what might be going on here?

its not back feeding through the relays, as i removed them and the wire still outputs power when the igintion is turned on.

i originally thought maybe it had something to do with the STA wire, as it stated that when its not in the crank position it would have been grounded to earth. But even with that wire earthed the MEL-R wire is still turning one when the igition is turned to run.

other than that, the car runs fucken mint!

just wont swtich off haha

[Guest Seedy Al]

na havnt sorted it yet, just heading to work now to have a look at it.

will try switching the batt terminal through a relay, see if that helps

As for what your saying.... yeah I have everything switching through the main relay, the write up i read didnt suggest anything about running such items through a different relay. pretty much all suggested through the Main relay....

Might have a look over some diagrams and see maybe

[Guest Spencer]

Phone posting so deleted that post by accident lol.

100% on the crown the ignition or injectors were on a separate feed. Some are on a black-orange wire, some on a black red? Dunno man can't remember the colours.