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Poor idle


Smith17279
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Hi all, i have a 2015 auris 1.2t, had it from new and been a great car, but for the past year or so its started to idle poorly, when coming to a stop it drops rapidly to 500rpm then goes back up to around 600 rpm, it judders like its missing, been in to toyota who cant find anything wrong.

Ive changed the plugs, coil packs, gave it a service, which i do regularly but still no better, tried to reprogram the throttle body but no joy.

Any suggestions would be great

Thanks all 

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Some common culprits whenever I read about similar issues seem to be dirty/duff MAF sensor, leaky vacuum line somewhere or bad fuel.

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As Cyker suggested, check Maf(cleaned it out) and also check for any vacuum lines that might be torn.

Maybe get a Carb/ intake cleaner to clean the throttle body and also when does it idle poorly(hot or cold) ?

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  • 3 weeks later...
On 7/26/2021 at 6:05 PM, AurisUK said:

With the car running, unplug the MAF. If the car runs normally again then there is your issue.

Ive unplugged the maf, it does idle but will only rev to 2500, ive cleaned it with throttle body cleaner, which i got when i stripped the throttle body.

Checked for air leaks but nothing, the car still runs like new, sometimes poor on mpg but that could be part of this problem. 

Starts up ok everyday, idle doesn't drop until its completely warm and at its optimum operating temp.

Toyota thinks it could be an ecu issue, but im in second thoughts about that

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My car does the same thing 

I have an Auris 07 1.6 and I cannot figure out what it is as it feels like a misfire. 

I have looked online and people have replaced the intake manifold gasket and that's sorted it but I don't know. 

 

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The car runs, drives, idle poor, but does not die. Mine does the same thing sometimes, it drops the idle as much as it can (when warm), and with aux off, but i never saw it as an issue. When i turn the A/C, or xenon lights, it adjusts the idle accordingly to the load.

You can try to reset the idle, that is remove Battery for 10 minutes, reconnect, start car and let  idle for 10 minutes, then take for a short drive.

 

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Throttle body cleaning helps most of the time and it’s a good idea as preventative maintenance every 40-60k miles. Here is the guy that shows how to do it. 👍

 

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19 hours ago, TonyHSD said:

Throttle body cleaning helps most of the time and it’s a good idea as preventative maintenance every 40-60k miles. Here is the guy that shows how to do it. 👍

 

Ive cleaned the throttle body several times with no joy, cleaned crank, camshaft sensors, cleaned egr valve, cleaned the maf sensor, ive even blocked up most of the hole on the maf just in case its reading wrong, only thing to check is the coolant temperature sensor 

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26 minutes ago, Smith17279 said:

Ive cleaned the throttle body several times with no joy, cleaned crank, camshaft sensors, cleaned egr valve, cleaned the maf sensor, ive even blocked up most of the hole on the maf just in case its reading wrong, only thing to check is the coolant temperature sensor 

Ok, have you done any work on the fuel injectors? A good idea is to use some quality additive in the tank and give it a good half an hour at least drive on the motorway. Something that I can recommend to you is wynns catalytic converter and lambda sensor cleaner, works really well if done as per the instructions and helps, I know from personal experience. Other than that can be a vacuum related.

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Hmm, the weird bit is you mention it's fine until the engine warms up and that's when it starts acting up.

Usually idle issues happen when the car is cold and go away when it's hot (Partly why I always tell people to be suspicious if they go to test drive a car and it's already been warmed up!), so I'm a bit stumped with this being the other way round!

 

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14 hours ago, Cyker said:

Hmm, the weird bit is you mention it's fine until the engine warms up and that's when it starts acting up.

Usually idle issues happen when the car is cold and go away when it's hot (Partly why I always tell people to be suspicious if they go to test drive a car and it's already been warmed up!), so I'm a bit stumped with this being the other way round!

 

Yep, me also, been working on cars since i was 10 with my god father, im now 42 and been doing it for a living for 14yrs, wondering if toyota are right it being the ecu

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  • 2 weeks later...
On 8/13/2021 at 1:55 PM, bobby boy said:

A long shot this, could a sticking pcv valve or blocked pipework to it be the cause?

Ive checked the pcv valve and it seems to be working fine.

Tested using the paper over oil filler trick, pulled the paper quickly and tightly, so again im out of ideas.

Noticed when the ac on, it drops to idle really smooth like it should do, but it only idles around 750rpm not at nearly 1000 when it was new

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If that engine is direct injection the reason can be dirty intake valves, something common on all direct injection engines. Sometimes as low as 20-30k miles are enough to cause trouble. The thing is that if you put any additives into the fuel they may only help to the injectors but not the valves since all goes straight into the cylinders. 

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  • 4 weeks later...
On 8/23/2021 at 6:34 PM, TonyHSD said:

If that engine is direct injection the reason can be dirty intake valves, something common on all direct injection engines. Sometimes as low as 20-30k miles are enough to cause trouble. The thing is that if you put any additives into the fuel they may only help to the injectors but not the valves since all goes straight into the cylinders. 

Would a carbon clean through the engine clean the valves? I know theres loads of places doing this now

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2 hours ago, Smith17279 said:

Would a carbon clean through the engine clean the valves? I know theres loads of places doing this now

Hi, it might do but I haven’t done anything like that myself and I am afraid I can not help with advice, best to properly diagnose the issue first then to look for a solution, the idea for the valves comes to me as I have seen some examples from other makes like Vw that has very dirty intakes since the fuel goes straight to the cylinders and not able to clean the valves. There are some YouTube videos that might be helpful. 

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On 7/19/2021 at 9:43 AM, Smith17279 said:

Hi all, i have a 2015 auris 1.2t, had it from new and been a great car, but for the past year or so its started to idle poorly, when coming to a stop it drops rapidly to 500rpm then goes back up to around 600 rpm, it judders like its missing, been in to toyota who cant find anything wrong.

Ive changed the plugs, coil packs, gave it a service, which i do regularly but still no better, tried to reprogram the throttle body but no joy.

Any suggestions would be great

Thanks all 

You replacing things that are not needed. We should never guest replacing things without proper diagnostic, coil packs is expensive and Iridium plug last at least 120k miles although in UK they suggests 60k miles unlike in USA.  For  me it looks like vacuum leak somewhere. Remember when it started and what did you do to the engine previously.   Clean throttle body may fix it if you ever disconnect 12V Battery because the relearning process started with dirty throttle body. Lastly, do compression leak down test check if one of your intake valve not seal properly.   Cleaning it with walnut blaster is the best option, nothing works besides mechanically clean the intake valves on direct injection engine. If the problem mainly at idle, vacuum leak and throttle body are the main cause.  Does it also do it when the engine is cold, not fully warm up? 

EGR valve provlem can be tested by unpluging the cable to EGR motor. If it runs smooth if you unplug it, you find the culprit. But usually only at light load after engined warm, cleaning the intake manifold is mandatory when having EGR service. 

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  • 2 months later...

Hello I own a Corolla 2019 1.2 turbo! 

EXPERIENCING the same issue!! 

35 000 km 

When a/c is turned on idle is almost perfect as stated in service manual 650 to 750 rpm....

More like 700 rpm in real 

When turning off the a/c, idle goes Nuts from 580 rpm to 850 rpm up and down suddenly like loosing a cylinder! 

No check engine nothing.... 

Suspecting carbon on intake valves, or clogged direct injectors.... 

Anyone made sense of the issue or figured it out? Screenshot_20210923_221027_com_ovz.carscanner.thumb.jpg.f0ebd7894bcbcf3790a22dc785b39070.jpg

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