Fast idle when cold 2.7

Dads 05 2.7 Tacoma idles really high when cold. Didn’t pay attention to the tach, but it’s probably around 150p rpm. After a few minutes it’s fine. Any common problems to look for?

 

1500 RPM on a cold start is normal. It is compensating so that you can drive off in 5 seconds. Cars with carburetors (anyone remember them???) did this via a fast idle cam on the carburetor.

 

The ECU does this on purpose to heat up the cats so they become useful as fast as possible. This is purely for emissions reasons

 

That makes sense on a MT. Do the AT trucks do it too? It’s fast enough that I wouldn’t want to drop it into R or D.

 

Normal warm up sequence.

No worries.

Cars, trucks.....have been doing this since well before CATS were needed.

The fuel mix is made rich on purpose for the simple reason, the cold fuel doesn't vaporize very well.

 

Yeah, both my Tacoma and 01 diesel e350 van have a high idle on cold starts, both are auto. However, my van drops rpms when I hit the brake so I can shift into a drive gear. I wish the Tacoma would do that too, but it doesn't.

 

Cars have been doing this automatically since the end of mechanical choke pulls (when you had to manually do it yourself with a pull knob on the dash). Before there were catalytic converters etc... Primary purpose is for drivability at a cold start.

Hard to believe this is even a question.

OP you are fine, it is totally normal.

 

/\/\/\/\/\ This, plus the O2 sensors have heaters in them for light loads and to help warm them up faster. If you've recently disconnected the battery, it could be a cause of a higher than normal idle due to the ECM needing to "relearn" the idle speed curves