4.0 High idle on startup

My 2005 4.0 L roars on cold startup. I’ve only had it a couple of months and it has done this since day 1. It idles at around 1000 rpm but as soon as you put it in gear it quiets itself down at around 700 rpm. Is this normal?

 

Yes, but more so on cold days.
Any ways, yes. It’s normal.
It should idle at a lower RPM once warm.

 

Yeah it's normal. Is this your first car? Every vehicle does this, unless it's an electric vehicle of course.

 

No this not my first car. I know that all cars idle a little higher until warm, but I have never had one that is this loud. I was just curious what rpm’s other people see. The engine is still cold when shifting into gear but the rpm’s lower by around 300.

 

Are you concerned about noise or RPMS? 1000RPMs is what I see at first startup in the A. M. and the noise is not at all unusual.
You say you've had this truck a couple of months. Maybe you had a small car before, that was by design, quieter than a 6 cyl 2nd Gen Tacoma.

 

Normal, depends on what the fan clutch wants to do as well.

My truck right now roars like a mofo in the summer, but in winter quiets down.


If you want better control of idle and throttle. Look at the write ups to clean the throttle body and mass air flow sensor. (MAF) These trucks really like it.

 

The computer's goal is to get the engine up to operating temps as fast as possible, and a high idle helps with this. The catalytic converters also need to light off, so in addition to high idle, it usually dumps a decent amount of fuel too.

What you are hearing (and smelling with the fuel) is a combination of this along with the clutch fan engaging.

Totally normal behavior. Just wait until it gets really cold out.

 

Totally normal! On a 2005 the main noise you need to be worried about on a cold startup is the sound of water rushing from under the dashboard. If you hear that...

My best advice since you just bought it is to post here, I'll tell you how you can trade in the truck without them knowing it has defective head gaskets.

 

The computer is trying to get the engine to running temperature. That's why you hear the high RPM's. When you shift into gear, the computer is smart enough to not put the truck in gear at a million RPMs, lol! When you shift, The computer drops the RPMs to what the transmission can handle.

This is not required, just personal preference on all my vehicled, I always start it, let RPMs settle, then drive. You don't have to, but if I'm not in a hurry, why risk it, the engineers believe it or not know more than me!