2JZ weird High Idle problem

[takai]

Right, what i would normally consider to be quite an easy problem has turned into a headache.

The 2JZGE in my MX83 has decided to do the opposite of the normal startup routine.
It starts with idling at around 900rpm and bouncing the idle slightly, and then as it warms up it gets progressively higher finishing at around 1600rpm.

I originally thought vac leak, but i cant find any leaks with any accelerant, and the vac gauge shows 9-10psi which is around 20in/Hg 500mm/Hg or around normal for all the Toyota engines ive had sofar, and pretty much the same as Gav's 1JZ.

Next thing i thought was a sticky ISCV, but ive cleaned that thoroughly, and yet the problem still occurs.

What has me stymied is that the idle increases from cold, rather than decreasing or just staying high.

Any ideas?

[wilbo666]

Would be amazing, but ISCV wired up wrong? / back to front?

Cheers
Wilbo

[takai]

I didnt touch ISCV wiring at all, so if that was the case you would think it woudl be the case on the original engine.

Would be interesting to know though, any ideas on how to check while the engine is running.

[wilbo666]

Sounds unlikely then... but what about unplugging or blocking the ISCV (just after when it starts so it isn't fully open if you unplug it) and seeing if the revs still go up?

I can't see how that could be the problem tho if you haven't touched the wiring!

Cheers
Wilbo

[takai]

Gav came over today and figured it out for me. Kind of forgot that there is an idle screw on the TB, which meant it was idling high anyway. NFI why it was increasing in idle though, must have just been the increase in vac as it warmed up.

[Gavatron]

All aboard the fail boat! Wooo Wooooooo!

[PlacentaJuan]

All aboard the fail boat! Wooo Wooooooo!

how long have you been waiting to finish your 1jz conversion before you pulled that one out?

what does the idle screw look like? is it the thing that adjusts how much the butterfly is opened?

[takai]

Idle screw == throttle stop screw