Low Idle at stop light

I pull up to a stop light and and sit there for 1-2 mins the truck will idle between 500 to 800 rpm. I know idle should be around 600-800 but it tends drop to 500 for a little for 1/2 - 1 1/2 secs and the computer slowly figures thing out and returns to around 650rpm. It happens with the A/C on or off. I found it really doesn't matter.

I started to notice it when I would feel the truck start to shake at the stop light and now I've been able to repeat it several times.

Truck is a 2023 crew max non-hybrid SR5 with 2,500 miles on it. I drive it with the auto-start/stop feature pushed off.

 

Don’t they cycle the port fuel on and off , maybe that’s it

 

Have you experienced this before Breathing Borla?

 

I don’t think I have , I’ll pay closer attention next time I drive

 

Mine runs slightly rough when at a stop light. My 3.5 ecoboost did the same. I learned to ignore it.

 

Thanks iforceAZ & BreathingBorla. I just wanted to make sure that this was normal. I will be scheduling my appointment with the dealer in the near future for the "fuel leak risk" and before I do, I wanted to see if anyone else is experiencing the rough idle.

 

Have you disconnected your battery recently?

nm, it’s a brand new truck. Was possibly thinking it may be a dirty throttle body

 

Hi Tsm503, The battery has never been disconnected.

 

I noticed the idle fluctuates when the AC compressor turns on and off. The idle drops pretty low, like in the 500s but I’ve never had it happen when the HVAC was off.

 

Normal in my truck to do that low idling. I was concerned at first but now ignore it as it seems to be regular business.

 

To xc_tc - I've tried both ways, A/C on and Off and it doesn't seem to matter.

To 22whatwedo - I don't know if it's "normal" but its good to know that I'm not the only one. Now we just need to find out from Toyota why this is happening. I feel this should not be "normal" and the ECU may need an update.

 

Happens to me too, tried to search around for why it was happening. I’m paranoid from owning an infiniti before where the idle drops are frequent and never good news lol

 

0.5 seconds........call the idle police

 

Mine does run rough during some of the red light idle stops. I thought that this was when truck switches between direct injection and port injection to clean the injectors? Just my guess

 

I recently installed a Scangauge III and noticed my RPM at idle ranges between about 560 - 650 depending on if I have the AC running. AC off, 560-595 RPM, AC on 640-650 ish. All smooth and no shake though... also, just a regular 3.4 TT, non hybrid.

 

mine does that now i feel better im not the only one that has this truck has 17000 on now

 

Mine has done this since day 1 and im closing in on 20k miles. It made me uneasy at first because it felt like it was trying to engage the auto engine off, but then kept idling.

It is very consistent, so probably nothing to worry about. I did notice that it does it more when I am using AC and accessories, so might just be more pull on the alternator

 

On my 2022 tundra limited hybrid the tachometer needle disappears when not using ice an also dissapears when on ev .engine shuts down but not noticeable unless compressor kicks in.Also ev torques up off the line to boost ev very quick

 

I guess I'm not the only one which is good to hear. I'm still puzzled as to why Toyota tuned the truck to run at a lower rpm for short periods of time.

So far we have "switch from direct injection to port injection to clean the injectors" as one theory.

 

My theory is that it almost thinks it should go into “stop mode”, even when it’s cancelled (which I do religiously). A few things about driving it makes me feel like it was designed for hybrid first and so some of those are left or imprinted, the other notable ones being the throttle lag and rolling stop situations where the transmission seems to “think” for a second. I am thinking the electric motor/battery would be filling all those points in. I have over 26k on mine and am used to it and have adapted to the way I feel the vehicle responds best, so no worries on my end.