Resolving a rough idle and miss once car is warm

[trd_st184]

Hey all,
I have a Toyota Caldina ST215 which has the Gen 4 3sgte in it, I have noticed the car has a rough idle and a miss when the cars warmed up.

The car has sold and I wanted to get it all resolved for the new owner as part of the sale.

I changed the plugs recently, but they were gapped correctly as speced by Toyota.

I know the car has a VAIC valve which controls the air intake, I am wondering if the miss could be caused by a low idle of around 500-600rpm.

Any advice would be fantastic, thanks in advance

[Muzza]

Yeah id do a step by step process, start with the easier ones first

check (all) the plugs, see if the engine is running rich, if so then check all the wiring around the ignition side (no broken wires, loose plugs)

with that valve, have the engine at running temperature and there might be a hole just in front of the throttle, place ur finger over the hole and n feel if there is any vacum. there shouldnt be when the engine is warmed up. if that the 3sgte is designed that way.

or even maybe just bring up the idle at the idle screw.

[trd_st184]

Yeah id do a step by step process, start with the easier ones first

check (all) the plugs, see if the engine is running rich, if so then check all the wiring around the ignition side (no broken wires, loose plugs)

with that valve, have the engine at running temperature and there might be a hole just in front of the throttle, place ur finger over the hole and n feel if there is any vacum. there shouldnt be when the engine is warmed up. if that the 3sgte is designed that way.

or even maybe just bring up the idle at the idle screw.

Thanks for all the suggestions Muzza,

I'll do bit by bit to see what could be causing it. I have a feeling it could well be the idle. I would have thought that with the car having one of those idle speed control valves that there wouldn't be an overide.

Could the other choice be raising up the idle from the bolt on the throttle body that limits/changes the default position of the throttle body.

[Muzza]

what does your engine idle a during warm up?
yeah have a go with the idle screw to raise the idle a bit.

[trd_st184]

It doesn't seem to miss (or as noticable) when its warmed up so it could well be that the motor is having trouble sustaining a reasonable idle due to the revs. It really does sound too low.

Thanks