Idle rpm fluctuate

[Agurkmix]

Hi.

Recently bought a rustbucket of an Avensis 🙂 and it`s having som issues with the idle rpm. Its a 2010 1,8 petrol engine. 2zr-fae.

The problem is as follows:

When I`m driving along and push the clutchpedal for a gear change or to stop in an intersection, it will rev up and down from 1000-2000 and sometimes higher for sometimes a few times or sometimes until the car stops and then it calms down to a normal idle rpm. It doesnt do this up and down revving when I`m standing still. Although it is a little high when I start it up cold. 

Another thing that seems connected to this is that the car judders when I`m slightly on or off the throttle when this is in effect. Like it jumpes from 0-10% throttle on or off. 

When the rpm fluctuation goes away some seldom time, the judder also disappears and everything is like it should.

 

Does anyone have a clue as to what can be causing this?

I`ve cleaned the throttlebody without success and checked some vacuum hoses and they seem fine. The problem was the same before and after sparkplug change.

 

Any suggestions are welcome 🙂 

 

 

[avensis_2018]

Clean the muff sensor with contact sprey, also clean all the pipes that goes from the air filter to the engine, clean with carb sprey and some fabric the turtle from outside and inside till where you reach to do so.

[Agurkmix]

Forgive my ignorance, but what is muff sensor? I will give a proper cleaning a try 🙂

[flash22]

 Think he meant MAF sensor, or it was a Freudian slip

do you have a scan tool ?

[Agurkmix]

Ahaa! Yes I do have a cheap scan tool. Got no codes on the car.

[UlleB]

Hello friend and greetings from Denmark

It could be a lot of things but let's start with some basic stuff that could affect the idle. When I bought mine I did the following things just to prevent issues during my time of ownership, they're really cheap and extremely easy to do, I consider it regular preventative maintenance.

• Clean the MAF sensor with a cleaning agent made specifically for the purpose or at least some type of alcohol/cleaning agent that doesn't leave residue. This is important. YouTube is your friend for how to's here. 
• Clean the throttle body with appropriate cleaning agent (it's very easy to do while you're changing filter and cleaning the sensor)
• Change the air filter to a new and good quality filter (DENSO is OEM as far as I know, it's what I use)
• Buy a bottle of injector cleaner additive and add it to a fuel tank of V-Power or similar (optional) 
• Since the car is new to you, complete the steps above and give the car a good long ride and don't be afraid to really step on it (stay within the law obviously). This is otherwise known as an Italian tune up

All of the above won't set you back anything special and all of it benefits your car regardless.

If none of this works you can take a look at the fuel system. Maybe it's time for a new fuel filter or it could be a fuel pump issue.

[Agurkmix]

Thank you very much UlleB for the detailed response 😁 I will definitely try those things. Hopefully this will help 🙂

[UlleB]

Let us know how you get on and check this guy out on YouTube also

 

[Agurkmix]

I will 😉

[Derek.w]

This is nit picking but pay attention to the Jubille clips Red fixes on carb clear plastic is at air filter side.

I am refering to the plastic spacer seperating the clips wires. No idea why they are diffrent.

[Agurkmix]

Thank you Derek. I will 

[m456an]

I use to get high revs when I bought my Avensis but I believe it only happened every 2 weeks. So it seems a little different to your problem, but for the record all I did was clean the PCV (Positive Crankcase Ventilation) valve. They are very cheap but I just cleaned it, have not had the rev problem for 6 years.

[MrAurisT]

On top of all of the excellent advice above, which I fully endorse, check when the spark plugs were changed; if that can't be determined, a good quality set won't harm. 

[Agurkmix]

Agree 😊 I have replaced them 

[avensis_2018]

change the spark plugs

enjoy.

[Shavestick]

Something you said about the revs go up when you press the clutch pedal.

Apart from the steps described by others which I endorse, if none of these worked, get your clutch checked for wear.

[Agurkmix]

A little update. It seems the cleaning of the throttle body has worked somewhat. It's gotten considerably calmer regarding the revving and the throttle jump also is less. Seems I'm on the right track at least 😊

[Konrad C]

I have noted that when the engine has warmed up. Once in a while the engine will rev up on it's own. Since the car is manual, I have had it in neutral with my foot off all the pedals, and the parking brake and the revs suddenly go up then settle back down to idle. I started doing this a couple of years ago since the lockdown and after I reset idle due to a flat Battery. My car usage has reduced a lot, and my car is only used twice a week. Apart from that the car runs well most of the time. I will try some of the things suggested, especially cleaning the throttle body, MAF sensor cleaner and check the PCV. I have new sparkplugs ready to install. Just changed the oil and filter. I have run diagnostics on the car, and no codes. Also run Techstream with live data and again no problems. I will look into the problem soon and hopefully find the solution.

[UlleB]

12 hours ago, Agurkmix said:

A little update. It seems the cleaning of the throttle body has worked somewhat. It's gotten considerably calmer regarding the revving and the throttle jump also is less. Seems I'm on the right track at least 😊

Yes. I find this method extremely underrated. My throttle body wasn't even that dirty but my idle has dropped from around 1000-1100 RPM down to around 800 RPM which I think is pretty much the standard output. I just used plain acetone because it's what I had and most throttle body cleaners are based on that.

Right after fiddling with it the idle goes kind of crazy because the ECU has to relearn the idle, this is normal. Happy that it has at least reduced the scope of the problem a bit for you.