Hello,
I have a 2006/7 (last half year model before the redesign) Scion xB. It’s got an automatic transmission and about 37k miles on it. I’m the second owner, having bought it just off-lease last year.
I’ve noticed a brief lag/hiccup when it shifts into (what I assume) is 3rd gear. It only happens when starting from a cold engine - never once the car is warmed up. I’ll, say, pull out of my office parking lot, turn onto the main road, and want to get up to 35 mph. I’m fine through first and second but then around 30 the tachometer goes between 3.5-4k and the engine feels like it’s working a bit too hard. After a few seconds of this there is a (noiseless but perceptible) little hiccup and then everything is fine.
I’m just wondering if this is anything to worry about or if this is just part of owning a slightly underpowered little automatic. I want to ask my mechanics but I’m worried about looking dumb/not being able to use the right terms. Doesn’t help that they’ve known me since I was in diapers.
Many thanks!
If it hasn’t been tuned up in a while, it may need new plugs–consult your manual for the maintenance schedule. If your check engine light isn’t on, and this is the only hiccup the car has, count yourself lucky. Many car owners have it much worse, and slight drivability problems with a cold engine are common, even with today’s computer-controlled vehicles.
Be glad we don’t have carburetors and chokes to deal with these days.
Thank you for responding.
She’s in for her bi-annual lookup/seasonal tire swap tomorrow so I’ll ask them to look. This is the only thing even remotely wrong so I will happily chalk it up to a quirk 
Now is a good time to have the transmission fluid and filter changed (every 30k miles).
I would probably be running this through a local transmission shop. If your regular mechanic is not a transmission specialist I wouldn’t ask them about it at all.
When you say the tach goes to 3.5-4k are you saying that this happens really fast - like a bit of a sudden revving? Or are you saying that it just seems to be hanging in 2nd gear too long?
At 37K you are a bit past due to have the transmission pan & filter serviced. So asing a local transmission shop to service it and check things out might save you headaches in the long run.