2JZ-GE Idle Weirdness (Help me!)

[takai]

So the 2JZ is idling again, but every now and again it seems to drop the ball, almost like an ignition failure or similar. Its also idling at around 2000rpm, which is a touch high.

http://www.youtube.com/watch?v=-iLXhsagwBE

Thats the video of it, i cant figure out what is going wrong, it throws no CEL or anything like that, and its all just a touch weird. I donnt know if it can be heard on the youtube vid, but it gives a touch of a backfire when it drops, so im thinking ignition module. But ive tried two sofar. Ive cleaned the ISCV already, so i dont think its that jamming up. But other than that im a bit stumped.

My brain is fried as ive been away for the last week or so while being sick (and im still about 20% sick now) and so its probably something simple which im missing completely.

[takai]

Just tried it with the TPS and ISCV unplugged, no difference. Tried with a new TPS and the same thing happened.

[rob]

any power at all going to the iscv?

[PlacentaJuan]

one of those things that tells the engine to idle up like power steering pump line (air line i think) or 'a/c compressor on' wire.

but 2000 is pretty high for either of those anyway maybe or maybe it iwll go to 2000 if it thinks there is a load when there isnt.

[Norbie]

1. You have an air leak somewhere, or possibly the throttle plate isn't fully closing. That's the only way to explain idling that high.
2. The occasional drop in revs is the decel fuel cut. When the ECU sees zero throttle and greater than ~2000rpm it will stop pulsing the injectors.

[rob]

we have had 2000rpm idle from a fully open iscv

there was no power going to it.

[takai]

Ta norbie, i was going down that path. Especially as it idled better when we unplugged the MAP sensor.

Time to track down vac leaks... i HATE vac leaks.

So check the throttle plate, ISCV etc...

EDIT: have i ever said how much i hate stock ECUs...

[wilbo666]

we have had 2000rpm idle from a fully open iscv

there was no power going to it.

I would also be double checking power to the IACV.

First thing that come to my mind

Cheers
Wilbo

[takai]

Ok, will put that on the list of things to do.

[takai]

Right, yet to fire it up with a vac gauge to see what its actually running at, but the ISCV is getting 5v through the center two pins.

Not ever knowing what readings ISCVs should get is a problem, so does that sound right?

[Gavatron]

Stolen from a Wilbo post. 7MGTE but may be the same?

[CrUZida]

1. You have an air leak somewhere, or possibly the throttle plate isn't fully closing. That's the only way to explain idling that high.
2. The occasional drop in revs is the decel fuel cut. When the ECU sees zero throttle and greater than ~2000rpm it will stop pulsing the injectors.

If this was the case it wouldn't do the fuel cut when the TPS was unplugged, which it still does do.

Agree that the throttle plate it probably open to far, it should be 100% closed, and the TPS should be in IDL at this point. Fix those (if you haven't already) as they need to be done before any other idle issues can be solved.

[CrUZida]

Right, yet to fire it up with a vac gauge to see what its actually running at, but the ISCV is getting 5v through the center two pins.

Not ever knowing what readings ISCVs should get is a problem, so does that sound right?

Should be 12v

[wilbo666]

Should be 12v

Agreed. It should be +12V.

It should be +B that is switched by the MREL relay.

Cheers
Wilbo

[takai]

This morning i checked out the ISCV as per the instructions, and it came up fine.
So i pulled off the throttle body which was all sealing up nicely, and was fiddling around until i found that for some stupid stupid reason the TRC butterfly (which i have removed) shaft hole thingy goes straight through the ISCV feed line, basically bypassing the ISCV.
So this afternoon will be a trip off to Bunnings to get some metal putty or similar to putty up those holes.

Will have to check the voltage again, because all the other +B switched by MREL come up fine at 12v. Otherwise lots of stuff wouldnt operate...