LinkLichen

Hi, I own a 1998 SC400 (1UZ VVTI) when the engine is cold it idles fine at around 500rpms, when it's warm the car stalls unless I turn the A/C on setting the idle to 250rpms.

Parts I have replaced

• Replaced all capacitors in ECU
• Replaced MAF sensor
• Replaced Coolant temp sensor
• Replaced both VVTI solenoids

Tallyhoe

I'm not sure about the vvti, assuming it's no longer distributor and wires and has gone ignition coils. I would say IACV may need to be cleaned. Apples to oranges, but my 02 Celica had similar issues where it would drop the idle, or even stall. Once I cleaned it out it was good to go.

RudysSC

I'd definitely inspect your IACV like Tallyhoe stated to see if it needs cleaned. Did you replace your MAF with a factory part or an aftermarket unit? These cars really hate aftermarket MAF sensors...

LinkLichen

The only thing non-factory is the MAF sensor, ill definitely change that. Also, the 1UZ VVTI doesn't have an IACV.

Tallyhoe

It's called ISC or Idle Speed control part number 22270-50020. You may need a gasket for this, so buy that first, and then proceed with IACV cleaner and a q-tip.

RudysSC

^^ Thank you for that correction! And good call on swapping out the MAF. That alone may correct your issue.

LinkLichen

Alright while I wait for the OEM MAF sensor to arrive, yall got me scratching my head about the ISC I don't see it anywhere on the 1uz I swear the VVTI version doesn't have it unless I'm blind.

Tallyhoe

Here is a good source of information. I do believe it's that round thing in front of the intake manifold. Nestled behind the black plastic, below the Toyota symbol