2JZ high idle issue, possibly ground related?

[Dirgle]

I am currently completing a 2jz swap in to my MKIII, but I'm having a problem.

First what I have.
This is a stock 2JZGTE out of an Aristo, it's been put into my 1987 MKIII and bolted to a R154. Everything is together except the exhaust. At the moment it's dumping out of the y-pipe.

Now the problem. It's starts immediately and initial idle starts out at 1600 RPM, but over the course of 30 seconds the idle raises to 2100 RPM and stays there until the engine warms up. then the Idle starts the pulsate rhythmically between 2000 RPM and 1500 RPM. The car drives great except for the high idle. Now I've checked the ISCV(Good), MAP(reads perfect) and TPS(Seems good). One thing that does seem off is the E2 reference for the TPS, this is supposed to go to ECU ground. I'm reading 69 to 72 ohms on this wire. Is this normal? What should the ECU ground reference be? Any other ideas about my idle problem are welcome.

 

[tlo86]

so you didnt read to see if the tps was good? do you measure the output voltage for it i cant remember 0-5V or something?

 

[Dirgle]

TPS sensor itself checks good. Voltage readings on it are dead center of spec. However I'm wondering if the ECU reference for ground being that high resistance wise would cause a problem.

 

[tissimo]

Sounds like the ISC might be stuck... You can try cleaning it.

 

[Dirgle]

hey, tissmo. I've already pulled the iscv and one way valve. They wern't very dirty but i cleaned them anyways. The resistance checks good on it, and when installed on the engine it clicks four times when energized like the manual says.

 

[aphxero]

It still might not be closing all the way. An idle that raises as you warm up is definitely a constant air leak like an iscv that never moves. Try capping it When hot should idle much lower.

Dude I dont even have one so my idle is about 550rpm until hot then guess what? 900 all day.

 

[Dirgle]

When it was off(the ISCV), I ran it through the resistance checks listed in the TSRM, and then I applied voltage in the pattern shown and the ISCV ran all the way in and out without a problem. So the stepper motor is verified good. It runs perfectly in it's housing. If I had access to an O-scope I would verify that the ISCV drivers in the ECU are functioning properly. Unfortunately I don't yet. But I'm trying to get a hold of one.

 

[935motorsports]

If yours runs from a map sensor, then ANY intake manifold leak will raise the idle. Check for leaks.

 

[Dirgle]

Really? I figured because it runs from a map sensor connected to the manifold, leaks wouldn't bother it(Not that I think there are leaks). It sees any given pressure in the manifold and supplies fuel for that volume of air. A leak will just change the pressure, and the sensor will compensate for that.

 

[Supra-Man18]

Dude I dont even have one so my idle is about 550rpm until hot then guess what? 900 all day.

Hey ! thats the same thing my 1j does BUT i have an iscv... It would idle around 600-650.. And after a while jus stay at 900...U think maybe its not reading at all ? fault in the wiring ?

 

[Dirgle]

UPDATE

Ok, so I took the ISCV off again and ran it to the full closed position using the method in the TSRM, and then backed it off a couple of steps. Once reinstalled, the car started and nearly died. After keeping the engine going for a few seconds with the gas pedal it managed to idle on it's own at 650 RPM. But if I rev it the engine will nearly die on it's way back to idle. This leads me to believe the ISCV is not functioning, however the motor itself is good. So tomorrow I'm going to ohm out the ISCV wires going to the ECU. Hopefully I don't have a bad ECU.

 

[aphxero]

Okay okay get ready for it. PLUG THE ISCV! Then use the throttle screw to make it idle. how about cover the hole and physically watch the thing. Btw, when the engine is hot they basically stay shut.

I've NEVER seen a jz ecu broken in regard to idle control. Anyone else seen that?

 

[Dirgle]

I've thought about it, but it's there is no reason it shouldn't work. I plan to have A/C and I would like the engine to idle up when I turn on the headlights, A/C, Rear defrosters, ect. This is a nice feature of a computer controlled engine, and I want to take advantage of it. I'm also one of those people that it bugs the hell out of when something doesn't work on there car. If I just capped it and left it alone, there would be the nagging sensation "it could work if I tweaked it a little more". I would never be able to let it rest.

 

[aphxero]

Oh I didnt mean forever. Just to diagnose

 

[Dirgle]

Update

Problem has been solved. The ICSV is working great now. It turns out the problem was due to my own laziness. When I made the wire diagram for the harness I consulted various EWD to come up with what connections needed to be made. However for IK1 and IK2 (the big 2JZ body connector that is made up of 4 smaller connectors) I relied on this reference:

(warning- direct link to an excel file)
http://www.geocities.com/g099521/MKIII/2JZ_SWAP/pinout_test.xls

It says pin E3 is for "+12 volt for electronic controlled transmission solenoids"

After realizing there was no voltage at the ISCV I looked at the Lexus GS 300 EWD, it showed that while E3 does control the transmission solenoids, it is also a main +12v buss for several VSV's and the ISCV. Bingo! problem found, after connecting E3 to the wire coming off of C1 pin4 the car went back to idling perfect. Now I'm going back through to verify the wires listed in the excel file.

Now on to my other gremlins which I'll save for another thread.

Oh I didnt mean forever. Just to diagnose

Ah gotcha