Heating

[is200 Newbie]

Anyone else noticed that the heater comes on a lot quicker (heats up quicker)  if you use the car with the paddles when its cold instead of in auto?

The heater works fine but I have noticed it heats up quicker and hotter while using the paddles.

[steve2006]

Here's my theory.

Assuming the transmission has an intercooler radiator ( engine coolant radiator with an inbuilt transmission cooler) maybe the transmission fluid flow is greater and gets hotter quicker using the paddle shift. This would heat up the engine coolant quicker resulting in a faster heater operation.

There again perhaps the extra physical effort in using the paddle shift makes you feel warmer 

[is200 Newbie]

1 hour ago, steve2006 said:

Here's my theory.

Assuming the transmission has an intercooler radiator ( engine coolant radiator with an inbuilt transmission cooler) maybe the transmission fluid flow is greater and gets hotter quicker using the paddle shift. This would heat up the engine coolant quicker resulting in a faster heater operation.

There again perhaps the extra physical effort in using the paddle shift makes you feel warmer 

Makes sense - I do believe the gearbox is cooled.

Air vents pointed at fingers when using paddles = in the cold weather, especially after defrosting the car, but keeping the car planted on the road =  when getting it warm through using the paddles !

[Linas.P]

My guess is that you keep higher revs when using paddle shifters, hence the engine and gearbox heats-up quicker. It would be the same if you just stand still in P or N and rev the engine, obviously at 3k RPM it will heat-up quicker than at fast idle ~1.1k.

[EuroFighter]

Quick question, why does the IS250 rev 'high' when cold starting? Is it something to do with the VVTI / catalytic burning? I think it does this for a while (if idle) and then settles.

I love cold starts and seeing the exhaust condensation - with the twins pipes you see a lot of 'smoke' from the Lexus and other large engined petrol cars. I believe petrol burns at a higher temperature than diesel so this might be why too?

Sorry for my lack of knowledge.

[Linas.P]

To be honest I believe all cars has higher revs until they reach certain temperature (maybe newer cars thing). I hardly notice it, and I guess only because Lexus IS250 has rather low idle RPM when warm. On some older car I owned idle RPM were like 800, while cold idle was like 900.. so you don't notice it at all, while on Lexus is like 700 and 1k.

[peachy]

It's the same on my 250 when I start her up from cold. She revs high for a short time but soon settles down.

The heater on my new 250 gets much warmer than it ever did on my 220d. seemed to take an age to warm up but the 250 heats up in no time.

[johnatg]

It's the engine management system runs a richer air/fuel mixture (more fuel) on cold starts - in the olden days we had to pull the choke out to do that - and it raises the idle revs to prevent stalling.