bryan767

iTrader: (6)

i had my 1jzgte running perfect in my old sc300. i recently swapped everything over to a new shell and went single turbo.

for some reason when the car is cool for a little while, or if i take power away from the car and charge the battery (my alternator is on its way out) the car will start and run perfect. however, if i turn the car off and restart it (aka getting gas) the idle will be at 3k and hold. i can drive the car but everytime i clutch in the idle is at 3k.

i also noticed that when my turbo timer started the idle came down to the normal 900-1100 range. so i put the key back in and stopped the turbo timer and drove the car.. but this only happened once. iv tried to recreate this event but failed

you can hear the large tube in the back of the iacv sucking in alot of air and if you cover it, it idles perfectly. so for some reason the sensor is closing. it could be a issue with the alternator (the volt regulator in it is pretty much dead) and my volts range between 9.2-10v while driving.. yea i know it should be higher. i bought a new battery and a new alternator.. just waiting for it to get here.

but does this sound like a electrical issue or just the sensor gummed up. or should i just put a cap on the vacuum port (the big one) and just deal with having no iacv for cold starts.. that might suck during the winter though

bryan767

iTrader: (6)

iv come to 2 conclusions. either the iacv is sticking open once i start driving the car and it gets hot (motor hasnt been ran in a few months) and build boost.

or my alternator is messing with some sort of startup voltage - im replacing it today since it no longer charges my battery and im running at 9.4v while driving. im hoping its just my alternator and i kill 2 birds with one stone

99SC42

iTrader: (44)

first thing i would do i swap the ecu with another one and go from there.

Kira X

iTrader: (24)

I agree. Try another ECU and see if that helps.

99SC42

iTrader: (44)

Mine would run great then out of nowhere it will back fire and smoke and idle at 3500 rpm, the the idle would drop down to 200 rpm lol yes 200rpm then would raise back up to 2000rpm.
It will idle at 200rpm , then i would raise the idle to 750rpm and them 30min later everything will go back to normal like nothing ever happened so then it will stay at 1500rpm then i would readjust the idle back to 750rpm haha.
it would pop like it was hitting the 2 step rev limiter... lol that's 1jzgte eCU for you that's what it does.
The IAC valve would stuck open up and down till i unplug the iac valve and plug it back in then it would go away.

SC_coupe

^^This. I had similar issues and it was the valve sticking intermittently.

Try replacing the ISCV with a good used one.

I had idle speeds ranging from 350 and stalling last fall, up to 2800 this spring, but would run perfectly fine other times. Long story short after looking at many other potential causes (ECU included), my shop swapped the ISCV with another one and the car has idled like it should since.

bryan767

iTrader: (6)

i fixed the issue. turned out i didnt have the right coolant line attached at the back. and my alternator wasnt charging so the car wouldnt run correctly since all of the sensors were not getting the full 12v.