1jz vvti wont idle mx73

[dumbass]

Never play with any screws on throttle bodies unless they have been tampered with

When u fit an idle motor u need to keep revs above 1500 2000 for 5 minutes so the ecu can wind
It all out and all way back in so it finds its limits
I normally put a thin cable tie as a spacer to crack throttle open
If this doesn't help then it's either wiring or stuffed idle motor

U might have to put a scanner on it and see what ecu is trying to do

[George]

If I recall it properly, code 78 means failure of fuel pump computer / relay for low pump speed. It's nothing serious.
My repair manual gives a ballpark figure of 'proper' TPS voltages, I can type em here if you wish

Did you check ISCV's installation place for excessive carbon deposits? They usually prevent the valve from moving

[BLK_20v]

Putting a relay in and connecting the earth of it to the fpr pin will make code 78 go away.

Just power the trigger wire pin and leave the rest not connected

[sundee86]

Dumbass I simply removed the throttle body to remove/install the ocv.
While it was out I just probed the sensors and gave it a clean with contact cleaner and a toothbrush.

The secondary tps and the control motor still had the factory paint markings, so haven't been tampered with.
The primary tps had the paint marks broken, I removed it to inspect, but it's not adjustable anyway.

George - if you could post the tps test limits and reset procedure , that would be good, and settings for re setting throttle stop.
I cleaned out the iscv with contact cleaner, also removed the grommet and filter screen and cleaned them as well.
All nice and shiny now.

[sundee86]

Dumbass - what's the deal with that idle motor procedure?
Does it need a specific rpm? Any other requirements?

[George]

sundee86
regarding resetting procedure, there's none, however here's what it says
disconnect water temp sensor (for efi, that with 2 wires) , turn ignition on, disconnect and connect ISCV connector
Each time you disconnect and reconnect it (when ignition is ON) it must cycle from fully open to fully close to half open

[George]

then it has some words on the throttle pos sensor (as for the secondary throttle, just disconnect its sensor. It's ok to go on without it)
so the sensor terminals are VC,E2,VTA from right to left. E2 is negative common to all the sensors, that's how you ensure you're counting the pins from the correct side

VC-E2 : 2.8-5.4 kOhms
VTA-E2
fully closed 0.2-5.9 kOhm
fully open 2.3 - 8.5 kOhm

[sundee86]

Awesome, I'll give that all a go, and report back.
Did you have info on re setting the throttle stop?

[dumbass]

many years ago maybe it was for a 7m or something
I read u just need to get rpm over 1500 rpm and for around 15 minutes

that's y a good drive down the freeway is good
also if the battery backup wire to ecu isn't hooked up the ecu wont save the idle motor settings so
ive had some people not wire the mrel and the batt wire and idle motor does all sorts of weird shiet

[bk_]

Idle stepper motor needs to be 100% open when IGSW=off.

That's the assumption ECU is making about the absolute position.

OEM ECU won't control stepper at all (or attempts to close it 100%) if TPS idle switch condition is NOT met when going from cranking -> normal rpm condition (500 RPM?).

Hope that helps.

[George]

bk_ , there's no idle swith on main throttle in his engine
Personally, I've done a few JZ's (more n/a than turbo, vvti only), some had stuck ISCV, and a good touch of hammer always worked...not that I recommend it for anyone though )
they never needed any sort of highway drive, etc to settle to normal rpm

[sundee86]

Just got some odd reading from the tps.

E2 - VC closed : 3.53 Kohms (tick)
E2 - VTA closed : 3.12 Kohms (tick)

E2 - VTA open : 0.8 Kohms ... This is odd

Tps fail? Showing no tps error codes and car drives fine, it's just the idle that's the issue .

BK_ I only realised while testing the tps the other day, that there was no idol switch in the tps aswel.

I just tested the iacv +ve terminals.
Started car, running ,terminals had over 13.5v
Ign switch to acc - terminals lost power what seemed to be instantly!

The ecu is storing fault codes fine though.....

[dumbass]

Looks like your mrel is not working properly
Put a switch from battery pos to idle motor powers and hold power to idle motor for three seconds
Then switch off
Then restart car after afew minutes

[bk_]

if vvti solenoid is faulty, what's the fail-safe condition of the cams? should be OK for idle as far as I know.

Is it possible for solenoid to lock up in a position not suitable for idle?

To confirm if M-REL is working, idle stepper motor should be 100% open when IGSW=OFF.

A few times IGSW=ON/OFF and you can tell if it's OK or not. It should _always_ return to 100% open position after 3-5 seconds of IGSW=ON->OFF.

If there are no TPS error codes, then it's OK. I know on a 2jz vvti I dealt with, it had TPS error codes after installing a JDM e-throttle bypass kit, but TPS stopper needed re-adjustment to resolve that.

[sundee86]

Vvti solenoid replaced, vvti error code now gone, power delivery is very different now!

Going to test mrel...standby