High idle cold starts?

2005 Tundra DC w/ 4.7L V8. Cold starts the engine idles @ 1500rpm and as the truck warms drops to 600ish rpm. When I bought the truck I thought it might have a dirty throttle body but a good clean up and the rpm's are the same. Google search mentions this idle strategy as normal but I want to confirm as it is annoying imo.

Thanks,

 

My 18 does the exact same along w a slight hesitation upon start up when it’s ridiculously cold out. All normal from what iv heard and seen.

 

Normal, increase idle means hotter temp warming up the engine quicker.

 

All normal. My 2013 also does this, along with oil pressure.

 

Normal engine operation for most engines. Same principal as the choke and fast idle cam on a carbureted engine until it warms up.

 

The all do it. (that's what the service writer always says)

I bought my rig used with 20K miles on the clock ~ it's run at 1,500 RPM on cold start as long as I've owned it.
I'm not afraid of the idle speed so much as dropping the transmission in gear at that engine speed.
I typically sit and wait for the idle to hover around 1,000 RPM before putting it in gear ~ and yes, I've always been annoyed by this.

 

Normal operation for a 40 year old carb'd vehicle. I primarily own and work on domestic passenger & light duty trucks and start up rpm is no more than 1K rpms which doesn't last long. I understand higher rpm's mean faster idle warm ups but I usually start my vehicle and throw it in gear and off I go - "yay" to modern fuel injection.

 

Imo. 1500 rpm's is excessive. Waiting for the rpms to drop is way too much of a throwback to a cold blooded carb'd vehicle. I thought about changing the coolant temp. resistance to trick the ecm into thinking its warmer but not sure once up to temp if the higher reported temp would cause side effects. Would be nice if there were any ECU tuners can modify the Toyota Tundra warm up strategy.

 

I'd gladly sign up for a 'mod' on the cold start idle speed reduction ~ something I find quite annoying as do lots of other folks, too.

 

Good to hear this is sorta normal. I just put in new injectors and reset everything by leaving the battery disconnected over night. I wasn’t sure if it was cleaning the TB or just a normal of the truck

 

What I might do is record the coolant temp sensor temp @ a few ambient temps and then @ a 1,000rpm from a cold start. I would then have a resistance to work with. Problem with coolant temp sensors they are negative temp coefficient thermistors - as temps increase resistance decreases. Resistance would have to be lowered possibly by running a resistor in parallel.

 

I wonder if anyone running the air injection pump delete sees lower cold start up rpms; isn’t it tricking the computer thru the maf to think it’s above the temp to keep the pumps off? It’s kinda pricey but maybe look that direction for a diy

 

An engines air/fuel ratio requirement is different when the engine is cold compared to when it is warm, therefore the fast idle. If you tried to bypass the system you find yourself with a bad running engine until it warmed up.

With fuel injection the fast idle mode is so short (30 seconds to 1.5 minutes) I do not understand why it is an issue. Were you not taught about engine warm up during drivers education and to give yourself a few minutes for it?

 

I understand cold start warm up strategies but as I mentioned Toyota has a uniquely high idle strategy. I have not timed my Toyota's high idle times but it is more like 2 minutes. I am not suggesting to skew the sensor input to that of a warm engine just enough to lower the rpm's slightly. Might work might not and would be a simple resistor once the math is calculated. My drivers education was 35 years ago and extended warm ups were quite relevant. Honestly I am driving down the street in less than 30 seconds on a summer day.

 

different strokes for different folks....this ole fart loves high rpms on cold mornings, crank the ole jallopy, go back in house make coffee and Salsa Red has toasty warm seats and warm heat !

 

Normal. This must be your first Toyota

 

No behemoths allowed!

 

The 2002 Tundra V8 4.7 cold starts on cold mornings idles (in Park) around 1100rpm which I believe is normal per the manual specs. Drops to 725 once warm (in Park).

 

Remote start. Enough said.

 

Shoo!

 

i have a 2005 v8 tundra. doing same thing more or less. on first start of day (not just on cold days, but maybe worse when cold) it revs up to 1500+ rpm for less than a minute or so, drops to about 800 rpm. everyone seems to imply this is ok. but my question is that this didn’t start happening until the last couple of years. it did NOT do this for the first 200k or so miles.

 

My 2006 V8 has 74k miles and has basically always done this as far as I remember. Revs up to 1.2k-1.3k RPM, then settles out around 700.

I wonder what was wrong with yours the first 200k miles that it didn't?

 

Could be an IAT?

1500 seems high. Dunno if high idle gets higher if it gets colder.

 

Cars have been doing this since at least the 60s...my 67 VW has a bi-metalic strip that adujsts the idle speed mechanically for about a 1500 RMP when cold.

I've never had a car that didn't do this.

But I've also always lived in cold climates so its always been obvious.

Be glad it automatically drops idle.

On my cars all the way up to the 80s, if you didn't go back outside and tap the gas pedal after a while the idle would keep climbing as the car heated up and it would be out their wailing away a 2K after ten minutes or so.

Used to be my 'job' when I was a kid and my mom was warming up the car....I felt very important running outside and getting to tap the gas pedal to drop it out of high idle.

 

Good to know it just wasn’t my family that experienced this as well.

We also had the screwdriver in the glove box to open up the carburetor throttle plate to get the car to fire up in case it was having problems.

 

Both my 2018 and 2000 do that. It’s more noticeable on the 2018 because the engine is louder

 

Ditto.

 

The high idle is very usefull in cold weather areas, your truck will warm up much faster, today when I drove the truck it was -6 degrees, I generaly have to warm my truck 5-10 minutes in the winter because I live so close to work.

 

My 2006 is the same way.
Struck me as odd at 1st, now I'm used to it.

 

For what it's worth, it's not even so much about warming up the engine faster, its that cold engines have a hard time maintaining a low idle. Simple laws of physics at work here.