Idle, PAIR Valve Removal, other questions

[PHeller]

Ok, so first question is a common one. I've done research, looked through like 10 pages of "ka24e cold start idle", and not found something pertaining to my idle problem.

My issue is slightly different than most.

- Car idles at 700rpm when warm - Idle bounces a small amount (about 50-100rpms, slight needle movement) - On colder days, the car will stall/rough idle until warm, requires feathering of throttle - Car runs awesome, cold or hot. No stumble, hesitation, etc.

I've crossed off a few things: it doesn't idle high, it doesn't stumble, once warm it idles fine, which tells me the MAF is probably ok, as are the plugs/wires/dizzy.

- I've still got the PAIR valve (will it trip a engine light if removed? any decrease in mileage if removed?) - I need to change the fuel filter, but I couldn't see the filter making a hot/cold difference - Coolant temp sensor? Possible, but does this cause hot/cold idle differences? - IACV - last resort, as its difficult to get to and clean.

Sorry for asking the question, but search doesn't always answer them.

[GO240]

actually getting to the IACV isn't to hard and it could be a learning experience and also the cheapest fix definitely not the fuel filter and if you remove anything pertaining to emissions your ECU will trip balls so yeah your light will come on sounds weird though my truck does the same thing though but my 14 hasn't ever done that just my old 13 (knocks on wood)

[Aaron D]

Another possibility could be fuel injector o-rings leaking. They could be cracked and allowing air to drawn in until the engine has warmed up the o-rings enough that they expand and seal off the crack.

A simple test would be to spray some WD-40, starter fluid, or some other like fluid around the injectors while the engine is cold and running and see if the engine idle speed changes. If it does, you've found the problem.