Idle issue

Hello,

I noticed that my idle goes up and down when i come to a stop. Sometimes it does and sometimes it doesnt. It doesnt feel like its going to die. Ive started noticing it within the last month. I have a 2020 trd offroad with 42k on it. anybody else experiencing the same? Does anybody have an idea what might be the problem? Thanks in advance.

tried to post a video but its not letting me.

 

Does it coincide with AC compressor cycle ?

 

Its probably normal, but with only a little info, can't say for sure. What is the lowest/highest RPM you see it going to when idling? Your truck has plenty of components that can affect the idle, and its very likely that whatever you're experiencing is AC related or power steering related, but of course this is purely a guess with limited info.

 

Nope A/C is off.

 

RPM 500 and 600

 

The AC compressor will cycle on and off on its own, independent of you selecting the actual AC button.

 

Thats not an alarming RPM and odds are its just your AC compressor cycling on/off, but if the surging idle is a brand new issue that you're positive was never happening before, or if you believe its surging more violently than it probably should, there's a handful of things you can check into. 42k on the truck, who does your maintenance? Ever changed your engine air filter? Possible throttle body clean, MAF clean, check spark plugs, etc.

 

@Paquo d Taco:
Did you perhaps have your defroster on? That will cycle the A/C also.

 

I do my own maintenance after the free once from the dealer. I have changed my air filter to K&N, last clean and oil was early July this year. Ill do that and see if it helps. I have done alot of offroading and overlanding with my truck and throttle body clean sound a good maintenance to do but i probly have to bring it to a shop since i dont know how to do that. What is “MAF clean”? Will check spark plugs as well havent done that since i bought the truck. Could it be a voltage issue?

 

Get rid of that K&N filter. Causes more problems than its worth. That's what most likely is causing your issue.

 

It’s not the K&n filter causing your issue, especially if it’s just a drop in panel filter. You’re fine running it, I wouldn’t let folks scare you away from it out of some hearsay bs. The only way a K&n filter would cause issue is if you re-oil it improperly after cleaning. A little bit of idle fluctuation is normal as long as it doesn’t vary a ridiculous amount.

I’d check the MAF that it’s not dirty, check the ccv, pcv and air hoses above the heads for vacuum leaks. If they’re not leaking, it’s probably just idle surge from the ac cycling on and off or the power steering pump.

 

I've seen people oil the wrong side of the filter and have this happen.

If the throttle plate is gummed up it can surge like this. I would leave the maf personally, the 3rd gens don't get dirty like the 2nd gen mafs.

It doesn't hurt to clean the plate, and if you disconnect the battery it will relearn the throttle plate adaptive and idle.

 

And there it is, suspect No.1

 

someone did tell it might be vacuum issue.

 

You brake booster doesn't run off of vacuum. Are you by chance moving the steering wheel when this happens? That will make the rpms fluctuate.

 

OP, EVAP Purge contributes to the idle fluctuation.
The clutch fan, a/c in different modes, lights increase the load on the engine. Also, on the hot idle, the engine will run on Direct injection mode to clean DI injectors.
here is the EVAP purge at the idle. RPMS fluctuate about 50-60 rpms.

 

The engine idle will go up or down when the fan motor is turned on. My tundra was the same.

 

Fortunately you don’t have a vacuum brake booster to go bad and cause this issue.

 

Thank you for everybody’s input and taking the time. Im glad the tacoma community is very helpful. Btw this is how my truck looks like.