wiring 1jz help needed please

[wilbo666]

Mu suggestions.

-Check the codes - the engine ECU 'W' pin will break out to one of the body loom plugs, so wire to it there.
-Check the TPS, the link is for 2JZGTE, but in my experience 1JZGTE should be the same so use it as a guide. wilbo666 / JZA80 2JZ-GTE TPS Settings.pdf
-Check the MAP sensor
-The MAP sensor output should read about 2.67V with the engine off
-The MAP sensor output should read about 1V with the engine idling (good vacuum)
-useful link http://www.toymods.org.au/forums/tec...identical.html

Cheers
Wilbo

[88cameron88]

my map sensor read about 4.5 volt to both wires on the map with the ignition on, engine off.
is this bad??

when you say the w pin will break out into the body loom plugs what do you mean.... are you saying bridge those 2 pins in the diagnosis box then run the text light over every pin in the 4 body loom plugs until i find the one showing the codes???

[wilbo666]

my map sensor read about 4.5 volt to both wires on the map with the ignition on, engine off.
is this bad??

Yes, that sounds bad.

Out of interest how did you measure the voltage at the MAP sensor? The MAP sensor needs to be plugged in of course.

Have you checked that the MAP sensor ground is correct?

when you say the w pin will break out into the body loom plugs what do you mean.... are you saying bridge those 2 pins in the diagnosis box then run the text light over every pin in the 4 body loom plugs until i find the one showing the codes???

Or you could use your multimeter to trace back from the engine ECU pin that is marked W on the engine ECU pinouts to the body loom plug that it comes out on

Cheers
Wilbo

[88cameron88]

just checked error codes, its throwing a code 12.

struggling to find a lot of accurate info on what code 12 is!

[88cameron88]

could this be an issue with the way i have wired up the neutral start??
i have just bridged 2 thick wires on one of the old auto plugs, i copied off a how to thread for a jza80.

[wilbo666]

It won't be the neutral start switch.


Are you sure you have a code 12?

Toyota Supra MKIV : Manuals

Code 12 is no crank angle or no cam position signals - the engine won't run without these signals. You say that the engine can idle so this doesn't make sense.

FYI: A good way to check that you are reading the codes correctly is to unplug something such as the O2 sensor, engine ECU coolant temp sensor, etc and check that you get the expected code (i.e. O2 sensor should generate a code 21).


Can you answer the below yet?

Out of interest how did you measure the voltage at the MAP sensor? The MAP sensor needs to be plugged in of course.

Have you checked that the MAP sensor ground is correct?

Cheers
Wilbo

[88cameron88]

ok with the engine idleing, i traced the map sensor wires back to the ecu and checked the voltage of the wires going into the ecu.
the 5 volt wire was reading 4.9volt
the other wire was reading 1.6volt.
so thats all good????

[wilbo666]

ok with the engine idleing, i traced the map sensor wires back to the ecu and checked the voltage of the wires going into the ecu.
the 5 volt wire was reading 4.9volt
the other wire was reading 1.6volt.
so thats all good????

A MAP sensor output voltage of 1.6V means that your boost gauge should show approx -7.7psi (~16in Hg) of vacuum in the intake manifold at idle on your boost gauge.

If the signal wire goes to ~2.67V when the engine is off (but ignition still on) then I would say that the MAP sensor is OK.



Have you checked to make sure that you are reading the check engine codes correctly?


Cheers
Wilbo

[midnight_purple_GA70]

It won't be the neutral start switch.


Are you sure you have a code 12?

Toyota Supra MKIV : Manuals

Code 12 is no crank angle or no cam position signals - the engine won't run without these signals. You say that the engine can idle so this doesn't make sense.

FYI: A good way to check that you are reading the codes correctly is to unplug something such as the O2 sensor, engine ECU coolant temp sensor, etc and check that you get the expected code (i.e. O2 sensor should generate a code 21).


Can you answer the below yet?



Cheers
Wilbo

if it is a jzz30 soarer 1j with loom and ecu it is possibly that the sta or nss wire might need to be grounded...

but his problem sounds different to the one ive experienced with a 1j conversion it would rev to 4500 fine but then miss and backfire... but it wouldnt miss under full throttle until that point...

was basically put in limp home mode...

[George]

for bypassing neutral start switch, trace ECU pins STA and NSW. They are usually black-white and black-red. Connect them both to starter relay coil positive terminal.

[88cameron88]

ok purple ga70 is telling me i may need to ground the sta wire. george is telling me to send it to positive....

can anyone give me a definitive answer to this???

the 1j loom and computer is jzz30 soarer.

im starting to think this neutral start business is my problem.....

ive swapped ecus, ive swapped ignitor, ive swapped the coilpacks. problem is still there.

thisafternoon it did rev fine with no miss till 4500rpm.

so can anyone give me a definitive answer on these sta and nsw wires???

thanks guys, really appreciating your help

[88cameron88]

A MAP sensor output voltage of 1.6V means that your boost gauge should show approx -7.7psi (~16in Hg) of vacuum in the intake manifold at idle on your boost gauge.

If the signal wire goes to ~2.67V when the engine is off (but ignition still on) then I would say that the MAP sensor is OK.




Have you checked to make sure that you are reading the check engine codes correctly?


Cheers
Wilbo

ill check what it is with engine off and ignition on in the morning...
also, i dont have a boost gauge hooked up yet....

[George]

wiring STA/NSW to positive relay coil terminal effectively grounds these two thru the coil winding (this is actually the way they are wired when auto transmission is in parking/neutral mode). But at the same time this way, when you turn the starter on, ECU will be aware of this. It will engage starting mode sooner. Engine would start a bit quicker

You might as well just ground STA/NSW pins. The only difference will be a bit longer time to start. In both cases ECU would think the box is in P or N position.

[88cameron88]

okay ill cut these 2 wires off after they come out of the computer and ground them to the body in the morning and see if this fixes my backfire problem.

do i need to do anything with the speed sensor wires???

[88cameron88]

okay ill cut these 2 wires off after they come out of the computer and ground them to the body in the morning and see if this fixes my backfire problem.

do i need to do anything with the speed sensor wires???