Intermittent high idle

[gtitdi]

I've noticed lately that sometimes the idle speed is higher than it should be - just over 1000rpm, instead of the usual 800-900.

I initially though it might have been the choke (or equiv.) but it happened yesterday when the engine was fully warm, so it can't be that.

When it happens if I turn the engine off and back on again it reverts to the normal idle speed.

The car is a 54 plate A3 Sportback 2.0TDI 140PS BKD.

Any ideas what might be the problem?

Cheers

[mjhayes73]

I have this same problem on my 56 plate 140bhp TDI passat. Just wondered if you ever found a cure.

[gtitdi]

Yeah, just the other week I was reading the self-study guide here [pg30]:

http://www.vaglinks.com/Docs/VW/Misc/VWUSA.COM_VW_MK5_Jetta_ElectricalSystem_SSP_873403 .pdf

And it appears it's not a fault, but a feature! The central electronics unit asks for more revs so that the alternator supplies more volts when the battery voltage dips due to high load. Makes sense as it mainly happens for me in the summer when the aircon etc is running, and at night when the headlights are on. Is that the same for you?

[alankru]

Yeah, just the other week I was reading the self-study guide here [pg30]:

http://www.vaglinks.com/Docs/VW/Misc/VWUSA.COM_VW_MK5_Jetta_ElectricalSystem_SSP_873403 .pdf

And it appears it's not a fault, but a feature! The central electronics unit asks for more revs so that the alternator supplies more volts when the battery voltage dips due to high load. Makes sense as it mainly happens for me in the summer when the aircon etc is running, and at night when the headlights are on. Is that the same for you?
Ah, I've been noticing the exact same symptoms over winter. I thought the same, that it was the cold, but I noticed that the revs returned to normal after a few minutes, which seemed to coincide with the fans speeding up to push hot air into the cabin. That would probably make sense if the heater was drawing load.

Thanks for that, that's been bugging me too!

[mjhayes73]

Yeah, just the other week I was reading the self-study guide here [pg30]:

http://www.vaglinks.com/Docs/VW/Misc/VWUSA.COM_VW_MK5_Jetta_ElectricalSystem_SSP_873403 .pdf

And it appears it's not a fault, but a feature! The central electronics unit asks for more revs so that the alternator supplies more volts when the battery voltage dips due to high load. Makes sense as it mainly happens for me in the summer when the aircon etc is running, and at night when the headlights are on. Is that the same for you?

I have had the car for 15 months and have never noticed this before (and I notice all noises and worries!!!!), so felt this wouldn't be the case, however I then read the link and feel that this could be applicable if the battery is on its last legs.

I am going to switch off autolights/wipers to see if this makes a difference.

Thanks for your help:beerchug:

[Simba2004]

Hi lads, I have the same issue. I have a car for nearly 2 months now and last month I noticed the idle is around 1050 RPMs as opposed to the usual 800. I noticed it gets worse in cold, damp weather. I always drive with lights on and most of the time the heater is on too, to prevent the windows fogging up. I was worried as when she does that first thing in the morning when she's cold, that's grand, but when she was nearly 90degC, that was bothering me.

So now, is this 100% normal or does that mean the battery is on its way out, like mjhayes73 said? The car is still under warranty from the garage so if it is any fault, I better look at it immediately!

I constantly have a trouble with the battery... I had 2 cars so far and changed batter 5 times! :zx11:

[alankru]

No, it doesn't equal that the battery is on its way out. My old A3 did it particularly in the winter and that battery tested fine and lasted years. Same with my brothers Fabia.
My new A3 has a very new Varta (~1 year old now) silver battery which has more capacity than the car requires. My car will rev a bit more when I've just been moving it in the drive a few times and not driving it anywhere. So, perhaps you are doing short runs and it isn't charging sufficiently?


Sent from my iPad using Tapatalk

[Simba2004]

Hey you might be on to something! I know for a fact she doesn't like the runs around the city because they're too short for her! She does great after 3.5 hrs drive I do every Friday and Sunday.
It must not be charging 100% during the city drives then, solution! :fest30:

[rowdy-999]

The battery is only used to start the engine. It isn't even in use when the engine is running. My work Skoda scouts used to have this trait of occasional higher revs.
Don't worry about it. When the engine fans are on you can also get a small increase in engine speed.

[EssexGonzo]

Could it be a forced DPF regeneration/clearout?

[Simba2004]

Well, the fans are working nearly all the time but the speed increase happens only sometimes? It is not the case that I am using the fan and it is up, it is just the odd day it does that - it can be fine for 2 weeks and then do it all day one day and go back to normal the next day.

EssexGonzo, please don't scare me, something tells me that DPF works would be very costly... Something I want to avoid, especially in a new car!!

[EssexGonzo]

Well, the fans are working nearly all the time but the speed increase happens only sometimes? It is not the case that I am using the fan and it is up, it is just the odd day it does that - it can be fine for 2 weeks and then do it all day one day and go back to normal the next day.

EssexGonzo, please don't scare me, something tells me that DPF works would be very costly... Something I want to avoid, especially in a new car!!

If I understand it correctly, and there are many many others who know far more than me, some DPF equipped models are meant to do this if you haven't done enough longer journeys recently to get the exhaust up to a high temp to burn off the soot. I'm sure I experienced the high tickover occasionally in my old car but never had any DPF issues, so it's not necessarily a problem.

[Simba2004]

Oh right, I didn't get you at first there. Right, well that could be it I guess, it makes sense there. As long as it is nothing to worry about, I am happy!
The key point, take home message I think here is to bring it on a longer journey once in a while to clean the DPF and not use it on short journeys (like a run to the shop and back on a cold engine!)

[Maccarone88]

Hi! i have an Audi A3 from built in Jan 2007 engine code BMN 170bhp SE TDI version.
i've noticed my car does the same issue. i had the car for 8 months.
i start the car and is around 850/900 rpm once all settle is 800rpm.
once i start to drive the car after 4/5 minutes the car start to over revving from the usual 800rpm to 1000/1050rpm.
it has never done it before (i bought the car back in december 2016) and now we are in Summer 2017.
all my friend audi's are going just fine at 800rpm once the temperature is spot on 90degrees.
it would make sense if yes i make short journeys in town and the car won't like it much but the truth is i am constantly on the motorway on 6th gear
driving my car at 70mph and exceeding it where i can.
so ir really doesn't make sense where the car is driven in motorway or town the rpm should stick at 800rpm winter or summer too.
have you noticed any change from winter to summer? is there any other member which could give me a more accurate explanation looking after the fact the car is driven both motorways and town and so that the town driving couldn't be the issue?
i replaced:
Solenoid pressure boost.
Temp sensor (brand one)
cleaned: EGR , throttle body.
Tested: Fan Voltage need , Alternator Voltage (13.10V so plenty to supply for all the extra accessories in the car)
oil pressure all good. i change oil every 6k and not 9k as the car ask me to do on the dashboard.
Anything else i might need to know why this happen? any updates would be really appreciated i don't think is an healthy thing running the car at 1000rpm as the clutch yes is to be used on the motorway and sometimes we press it whilst at higher rpm but when on idle and on traffic i don't think is built to get that amount of stress (and i don't like to ride the clutch on gear in traffic) so i leave in neutral when i have to stop.
thank you in advance for any update.

[Rob69]

Get it scanned for fault codes before changing any more parts

[Maccarone88]

Hi , thank you for the response.
i've scanned the car on a VAGCOM it only give me Stereo related code as its an aftermarket one.
then it give a 00361 which is related to heater element for auxiliary heater (could that be part of the problem?)
Also i was reading a lot thru the common blogs online and here Re increased idle - Audi Q3 Forums - Page 1 (http://www.q3ownersclub.co.uk/forum/re-increased-idle_topic1333.html) the car was presenting the same issue. i used not really pay much attention to my car temperature on how long it took to go to 90degrees but i've noticed sometimes it take quite a while and it can be related to a faulty Coolant Thermostat and i am really curious to change it usually doesn't bring a fault code.
any advice is always welcome and would help a lot on what to do.
thank you

[Rob69]

That Q3 article is on about a 2013 common rail engine with DPF, I think your will be a PD without DPF ? If it takes a long time to come up to 90'C and you notice the temperature dropping off if your are coasting down a hill or turn the heating up, then your thermostat is needing changing. My 1.9 tdi was sluggish to heat up and a new stat lets it come up to full heat in around 5 minutes or 2 or 3 miles of driving. I don't think the heater element code is causing the high idle 00361 - Ross-Tech Wiki (http://wiki.ross-tech.com/wiki/index.php/00361)
I've heard that a poorly performing alternator can cause the revs to increase to try and raise voltage, can you check the voltage output with a meter? Yours looks low at 13V It should be around 14 to 14.5 v running.

[alankru]

Hi , thank you for the response.
i've scanned the car on a VAGCOM it only give me Stereo related code as its an aftermarket one.
then it give a 00361 which is related to heater element for auxiliary heater (could that be part of the problem?)
Also i was reading a lot thru the common blogs online and here Re increased idle - Audi Q3 Forums - Page 1 (http://www.q3ownersclub.co.uk/forum/re-increased-idle_topic1333.html) the car was presenting the same issue. i used not really pay much attention to my car temperature on how long it took to go to 90degrees but i've noticed sometimes it take quite a while and it can be related to a faulty Coolant Thermostat and i am really curious to change it usually doesn't bring a fault code.
any advice is always welcome and would help a lot on what to do.
thank you
I don't think that would be the cause of what you are witnessing. With my first A3 (the one I had at the time of originally posting in this thread) I subsequently discovered it had the same fault code for the aux heater; I understand that it just means that in the Winter you won't get hot air out of the cabin air vents until the engine is warm. The auxiliary heater is fitted so that in the winter you can get hot air through the air vents quickly, as the diesel engine takes a while to warm up. Hope that makes sense?
Reading back through this thread, it was thought that the cause of the increased revs in Winter was the load from the aux heater...I didn't know at the time of my original post that it wasn't working anyway.

However:
My subsequent A3s have all done the same thing; idle revs increase on cold winter days.
My subsequent A3s also have increased idle revs when the car has been sitting a while.
This is when you first start the car - after a few minutes, things settle.

As you have explained, neither of these circumstances apply to you as you are experiencing increased revs after a number minutes.
With my 1.9tdi, I had heating up issues when the dealership left air in the coolant system. It worked its way out in the end and I topped up the coolant - it was then back to normal.

[Maccarone88]

Hi thank you again to take time and respond.

i understand that maybe that idle issue would have happened when the aux heater was not installed in certain models.
And i do get why it could have happened in the winter time in order to compensate cold outside temperature , slightly revving in order to warm up.
but why am i experiencing it in full summer time when outside is 20 plus degrees and is so random?
i mean traveling sometimes is all full at 1k rpm for the whole journey then other times same journey kinda quiet and showing it 2 on some motorway slip road/roundabout.
then if i turn it off and leave for a red light length of time and turn it on the car is on idle at 800rpm then 5 minutes gone back to 1000/1050rpm.
i don't think it should happen that's all at least no in the summer time.
thank you again.

[Maccarone88]

Hi thank you for the response.
my car is a BMN 170 bhp - bigger turbo and Siemens VDO Piezo Injector engines with DPF-- Read more at: ht (https://www.torquecars.com/volkswagen/2-0-tdi-140-170-tuning.php) - (c) TorqueCars
https://www.torquecars.com/volkswagen/2-0-tdi-140-170-tuning.php
this is the link with engine codes. mIne is the BMN 17obhp with DPF so i thought it may have been almost same specs on that point of view.
the car doesn't go down on temp if i am resting but it take a awful lot of time to get there even driving and sometimes fairly normal.
the garage mentioned that 13.10v on alternator is plenty enough but i didn't know it should have been 14/14.5v but they said on resting just on idle it was at 13.10
that might increase if the car is running. but i'll still mention it.
i guess is only a matter or power of deduction at this point. one by one the issue will come up and i'll keep everybody posted.
i still believe an audi once warm should not exceed 900rpm at idle and that is a fault and not a feature as mentioned in some other forum online.
thank you again. and another question would be: would the DPF play a role in with this issue? and how?

[Maccarone88]

That Q3 article is on about a 2013 common rail engine with DPF, I think your will be a PD without DPF ? If it takes a long time to come up to 90'C and you notice the temperature dropping off if your are coasting down a hill or turn the heating up, then your thermostat is needing changing. My 1.9 tdi was sluggish to heat up and a new stat lets it come up to full heat in around 5 minutes or 2 or 3 miles of driving. I don't think the heater element code is causing the high idle 00361 - Ross-Tech Wiki (http://wiki.ross-tech.com/wiki/index.php/00361)
I've heard that a poorly performing alternator can cause the revs to increase to try and raise voltage, can you check the voltage output with a meter? Yours looks low at 13V It should be around 14 to 14.5 v running.
Hi thank you again to take time and respond.

i understand that maybe that idle issue would have happened when the aux heater was not installed in certain models.
And i do get why it could have happened in the winter time in order to compensate cold outside temperature , slightly revving in order to warm up.
but why am i experiencing it in full summer time when outside is 20 plus degrees and is so random?
i mean traveling sometimes is all full at 1k rpm for the whole journey then other times same journey kinda quiet and showing it 2 on some motorway slip road/roundabout.
then if i turn it off and leave for a red light length of time and turn it on the car is on idle at 800rpm then 5 minutes gone back to 1000/1050rpm.
i don't think it should happen that's all at least no in the summer time.
thank you again.

[Maccarone88]

hi , i've inboxed you let me know if you have my msg. thanks

[Maccarone88]

Hi thank you for the response.
my car is a BMN 170 bhp - bigger turbo and Siemens VDO Piezo Injector engines with DPF-- Read more at: ht (https://www.torquecars.com/volkswagen/2-0-tdi-140-170-tuning.php) - (c) TorqueCars
https://www.torquecars.com/volkswagen/2-0-tdi-140-170-tuning.php
this is the link with engine codes. mIne is the BMN 17obhp with DPF so i thought it may have been almost same specs on that point of view.
the car doesn't go down on temp if i am resting but it take a awful lot of time to get there even driving and sometimes fairly normal.
the garage mentioned that 13.10v on alternator is plenty enough but i didn't know it should have been 14/14.5v but they said on resting just on idle it was at 13.10
that might increase if the car is running. but i'll still mention it.
i guess is only a matter or power of deduction at this point. one by one the issue will come up and i'll keep everybody posted.
i still believe an audi once warm should not exceed 900rpm at idle and that is a fault and not a feature as mentioned in some other forum online.
thank you again. and another question would be: would the DPF play a role in with this issue? and how?



Hello everyone. i hope you had a nice week after bank holiday week end.
as i stated i would have made and update of what is the cause of the issue. (potentially)

After Throttle body/EGR manual clean.
Carbon clean the whole system
changed solenoid pressure release valve (wich will need to go back at eurocarparts westwood cross becaue it cost 66gbp and i want them back as it failed)
Run VAGCOM 2 times and only showed error 00361 (aux heater element)

My conclusion is.
The aux heater completely failed and was on even when running on cold air. it was running yes but not producing hot air as the element was burnt out and somehow it was sucking electricity.
after that i discovered one of the radiator fan (driver side) failed so i replaced myself fro 62gpb
The battery was yes making the car start but it was knackered by this little things and time
So the problem was the car going from 800rpm to 1050rpm on idle , if you pay close attention the car only does that when the fans comes on.
meaning the battery is holding enough charge to make the car start petrol/diesel don't matter. once the car start and everything is running
the voltage produced is not enough to occasionally support both fans so the car start to rev up instead of taking electricity from the battery as there is some amperage there but again not enough so it rev up and compensate the lack of electricity by taking it from the alternator.

MY advice: anyone who has a TDI audi anything higher then 80kmiles just go with a mate battery and watch the car behaviour sometime the obvious answer is right there and we think is more complicated then what it is.
replacing EGR Throttle body is around 500gpb from a garage probably 250gpb if you do it yourself , replacing the fan 62gbp but a garage qould quote around 200gpb all this little things sum up so check fan first if they ran and car does that then is the battery.
hope this was useful to someone as it was for me.
thank you all

[Maccarone88]

I've noticed lately that sometimes the idle speed is higher than it should be - just over 1000rpm, instead of the usual 800-900.

I initially though it might have been the choke (or equiv.) but it happened yesterday when the engine was fully warm, so it can't be that.

When it happens if I turn the engine off and back on again it reverts to the normal idle speed.

The car is a 54 plate A3 Sportback 2.0TDI 140PS BKD.

Any ideas what might be the problem?

Cheers

Please read the last comment on that link it might help you out. cheers.
Intermittent high idle - Page 3 (http://www.vwaudiforum.co.uk/forum/showthread.php/89789-Intermittent-high-idle/page3)