? Regard high start up idle

[cbreze]

This seems normal so I'm presuming its not an issue, but the question is if the 4R is parked outside in subzero temps and I go to start it there is no control other than to have it immediately ramp up to a quite high idle for maybe 15 seconds then it drops to a more normal range. Usually the oil is down in the pan, but is having the 0W-20 synthetic in the truck the difference between a wearing issue and a nonissue? Not trying to second guess the toyota engineers Just wondering what others thoughts were on this. My tacoma doesn't start up like this, but it is 8 years older.

 

[ATL4R]

This seems normal so I'm presuming its not an issue, but the question is if the 4R is parked outside in subzero temps and I go to start it there is no control other than to have it immediately ramp up to a quite high idle for maybe 15 seconds then it drops to a more normal range. Usually the oil is down in the pan, but is having the 0W-20 synthetic in the truck the difference between a wearing issue and a nonissue? Not trying to second guess the toyota engineers Just wondering what others thoughts were on this. My tacoma doesn't start up like this, but it is 8 years older.

I've haven't seen a car made in the past 20 years that does not do this to some extent.

When the oil is cold it's harder to flow through the engine, I believe this is a partial reason of more fuel being dumped in the engine to overcome this friction... this is an assumption on my part.

I also recall reading some emissions program information a year or two ago saying that another reason for the higher idle is that the CAT does not work as efficiently when it is not "up to temperature" - running the idle higher for a while in the cold results in getting the CAT up to a more efficient temp quicker. You know.......wasting fuel to safe the earth.. typical EPA stuff :bash:

 

[cbreze]

I'm no oil expert but have heard that synthetic oil adheres to the necessary internal parts and such so when it's started there is some lube there already. Something the old Dino oils didn't do as well. Just seems to me a dead cold , sub zero temp engine doesn't need to instantly come to life at such a high idle. Higher than warm running temps, but not that high, that quick.

 

[Hellamatic]

It's the air injection pumps for the emissions system. It goes to high idle to facilitate the flow rate that the pumps are supposed to put out on startup.

 

[1engineer]

OP you have no worries. The synthetic oil in our engines does not change viscosity much between super cold and super hot the way conventional oil does. So at -50F the oil "thickness"" is fine to go to a high rpm. As a matter of fact your engine probably won't know the difference. It will take longer to come up to temp because the ambient temps are low but as far as the oil is concerned have no worries. A lot of stuff happens during start up and getting up to operating temp such as fuel and air mix changes and of course with that change emissions change as well. One last thing: synthetic fluid does not stick any better or worse than conventional oils. No assumption just fact.

 

[jspagna1]

You should hear my 97 4Runner when I start it. To this day after 170,000 miles and 15 years later it still idles high on start up then winds down. No problems at all. I wouldn't worry about it.

 

[cbreze]

Thanks, wasn't worried really, but its nice to be reassured.