High idle when its cold.

amitsekhon · Dec 20, 2017

I noticed few times,when its quite cold (-2 ~0 deg Celsius),engine idles at around 1050~1100 rpms even after coolant temp gets close to normal temp.It doesn't do all the time but have noticed quite a few times.

My first thought was car going through regen but that's not the case.I checked couple of times and regen was not active at that times.Has anybody experienced this?

tom61 · Dec 20, 2017

Yes, I thought the same thing last week when it was idling around 1100 rpms and it was at operating temp . It was pretty cold that night .

amitsekhon · Dec 20, 2017

tom61 said:
Yes, I thought the same thing last week when it was idling around 1100 rpms and it was at operating temp . It was pretty cold that night .

Thanks Tom for the confirmation. But it's strange that it idles high even when the engine and exhaust is fully warmed up?I hope its not any kind of sensor problem.I scanned the ECU and found no codes.

sands80 · Dec 20, 2017

Yes the car goes into a high idle mode when the heater is on and its cold outside. Ironically, turn the heater off and despite a cold Michigan winter day of 10F the car will idle nicely at about 750rpm.

The heated electric seats in the SEL are awesome.

Grigg3 · Dec 20, 2017

Mine also idles quite often at 1,000 rpm when cold out and is not always doing a regen.
Wondered if it was related to having the heater temperature knob all the way up, but it still idles fast after turning it colder.
One morning when it first started doing it I waited in the parking lot for quite some time idling, bumped the throttle occasionally and it never would settle down to a normal idle.

Guessing this is normal behavior and I just don’t know why?

thundershorts · Dec 21, 2017

The odd feature of idle dropping to about 750 with pressing brake pedal harder is disabled when the ambient temperature is below about 43f. I thought something was wrong until someone at the dealership gave me an explanation.

Grigg3 · Dec 21, 2017

Mine is a manual.
Even while driving it maintains the high idle.
One stretch of road I travel is slightly down hill and 3rd gear at a normal idle is the right speed, but at fast idle is faster than needed.

marcusku · Dec 21, 2017

I find it will eventully idle at 750 with the heat on but you have to run it quite a while before it decides it's hot enough--I find close to an hour.

Mike in Anchorage · Dec 25, 2017

Varies greatly. No idea why yet. Temps have been consistently below -5C, and sometimes the idle stays at just over 1000 RPM, and other times drop to 750 or so. I also thought regen, but that isn't the case. I haven't done a radiator cover on this one yet, so I'll see if that makes a bit of a difference.

turbobrick240 · Dec 25, 2017

Yeah, it's just the ecu doing its best to maintain optimal coolant temps. One of the six tune settings on my plow truck is high idle. I use it a lot during the colder months.

Edit: apparently the high idle may be more about supplying more current for electrical loads. Though my car will high idle when cold with no additional loads than what is needed to keep it running. Maybe because my battery is getting old, or because my Malone tune may have changed the high idle parameters.

VeeDubTDI · Dec 26, 2017

amitsekhon said:
I noticed few times,when its quite cold (-2 ~0 deg Celsius),engine idles at around 1050~1100 rpms even after coolant temp gets close to normal temp.It doesn't do all the time but have noticed quite a few times.
My first thought was car going through regen but that's not the case.I checked couple of times and regen was not active at that times.Has anybody experienced this?

It does high idle anytime the HVAC system is running the auxiliary 1,000 watt electric cabin heater. This is necessary so that the alternator can supply enough power for the heater. This specific high idle command can be viewed in the HVAC control module in VCDS.

amitsekhon · Dec 26, 2017

VeeDubTDI said:
It does high idle anytime the HVAC system is running the auxiliary 1,000 watt electric cabin heater. This is necessary so that the alternator can supply enough power for the heater. This specific high idle command can be viewed in the HVAC control module in VCDS.

Thanks for the info!! So do we have auxiliary electric heater in our TDI's?

Yes i found that if i leave my temp dial at a mid position,then it does not go into high idle mode but if i crank it up then it goes into high idle.

compu_85 · Dec 26, 2017

1996-2005 Mk3 / Mk4 VE and PD cars w/ manual trans: 3 coolant glow plugs. 2 stages, 120w, 240w, or 360w
2005 + PD and CR cars: Ceramic PTC heater in line with heater core. 2 500w stages.

The common rail cars can put a huge load on the 12v electrical system - after run glow plugs, 1000w of cabin heat, 200w of adblue heat, seat heaters, rear window defroster, electric power steering...

Don't be afraid to crank the temp dial up. The electric heater element really helps take the edge off as the coolant warms.

-J

aditud · Jan 2, 2018

Noticed this for the first time today. Car hadn't been started since Friday last week, today I drove it for 10mi around town in our suburb and even after it got to 200C (normal operating temp) the idle was at about 1050. There was a 15min stop in between but that made no difference.

Then, funny enough, I had the car sit outside (about -12C) in my driveway for an hour or so, started it again and drove about 4mi and the idle was at 750. Stopped for about 20min, drove back home and this time it was idling again at 1050. Seems so random!

I never noticed this behavior from the un-fixed GSW DSG I used to own (replaced by the current one in June).

aditud · Jan 2, 2018

Noticed this for the first time today. Car hadn't been started since Friday last week, today I drove it for 10mi around town in our suburb and even after it got to 200C (normal operating temp) the idle was at about 1050. There was a 15min stop in between but that made no difference. Also, turning the heat off made no difference.

Then, funny enough, I had the car sit outside (about -12C) in my driveway for an hour or so, started it again and drove about 4mi and the idle was at 750. Stopped for about 20min, drove back home and this time it was idling again at 1050. Seems so random!

I never noticed this behavior from the un-fixed GSW DSG I used to own (replaced by the current one in June).

740GLE · Jan 3, 2018

aditud said:
Noticed this for the first time today. Car hadn't been started since Friday last week, today I drove it for 10mi around town in our suburb and even after it got to 200C (normal operating temp) the idle was at about 1050. There was a 15min stop in between but that made no difference. Also, turning the heat off made no difference.

200C? super heated coolant system is very efficient but prob not the best for turbo life, 200F is more like it.

aditud · Jan 3, 2018

740GLE said:
200C? super heated coolant system is very efficient but prob not the best for turbo life, 200F is more like it.

Ok, so the temp gauge measures in F? Didn't know that, thanks.

Later edit: I noticed this morning that it says F on the gauge.

Mike in Anchorage · Jan 4, 2018

Mike in Anchorage said:
Varies greatly. No idea why yet. Temps have been consistently below -5C, and sometimes the idle stays at just over 1000 RPM, and other times drop to 750 or so. I also thought regen, but that isn't the case. I haven't done a radiator cover on this one yet, so I'll see if that makes a bit of a difference.

I did check this week. There is a difference when the temp for the cabin is set at full warm. There is an almost imperceptible click as you get to the end of the range on the knob. If you don't go that far, the car seems to idle at a lower speed.

amitsekhon · Jan 5, 2018

Mike in Anchorage said:
I did check this week. There is a difference when the temp for the cabin is set at full warm. There is an almost imperceptible click as you get to the end of the range on the knob. If you don't go that far, the car seems to idle at a lower speed.

Good find!! Will check it tonight.Thanks

aditud · Jan 5, 2018

Mike in Anchorage said:
I did check this week. There is a difference when the temp for the cabin is set at full warm. There is an almost imperceptible click as you get to the end of the range on the knob. If you don't go that far, the car seems to idle at a lower speed.

However, it's funny that turning the fan off completely won't lower the idle. Or reaching the 200F operating temp. The idle stays inexplicably at 1050. Then you turn the engine off and on again, don't mess with the cabin temp knob, and you may get a normal, 750rpm idle. Or not. I've encountered both situations.

Grigg3 · Jan 5, 2018

It still seems random to me too.
Is there any manual or literature that explains what the engine/computer is thinking in regards to the high idle.

St.Hubbins · Jan 5, 2018

reason # 104 why a simple dash-light indicator for regen would be helpful. ifs, how hard would that have been, seriously?!

compu_85 · Jan 8, 2018

Very expensive for VW... because of all the time their support people would have spent calming people down when "funny lights" kept coming on the dash.

That's the same reason the temprature gauge is just a glorified idiot light. It doesn't show the actual engine temprature.

-J

matteas · Feb 26, 2018

I'm seeing high idle turned on with heat on at 40 degrees Fahrenheit or less.
Turning the heat off and blipping the throttle to 2k rpm while idling returns to normal idle.
Good way to check if regen is happening or not.

whizznbyu · Feb 22, 2021

matteas said:
I'm seeing high idle turned on with heat on at 40 degrees Fahrenheit or less.
Turning the heat off and blipping the throttle to 2k rpm while idling returns to normal idle.
Good way to check if regen is happening or not.

What was VW thinking about when it designed the high idle feature to keep cabin temps toasty? Once the engine reaches operating temps, turning on the heat doesn't drastically drop the engine temps to warrant a fast idle.

whizznbyu · Feb 22, 2021

I wonder if a "Dynamic Idle" featured by Malone gets rid of this fast idle with the heat turned on below 40F.

740GLE · Feb 23, 2021

What's the oil temp when noticing high idle? Remember VW can bump up EGT for higher heat for the cabin when the oil is still coldish, but that creates more NOX, so I think they just bump RPMs to keep things happy.

whizznbyu · Feb 25, 2021

My engine high idles when outside temps are below 40F, AND when the heat is on. Does it even when oil temperature is 215F. Following Matteas' post I have found that turning the heat off and blipping brings it back down to 850-900. Then I though about how ridiculous it is to have to do that routine everytime so I am going to just leave it alone and worry instead about what oil to use next.

Mike in Anchorage · Feb 26, 2021

whizznbyu said:
What was VW thinking about when it designed the high idle feature to keep cabin temps toasty? Once the engine reaches operating temps, turning on the heat doesn't drastically drop the engine temps to warrant a fast idle.

Depends on the ambient temp. Which should probably be a part of the code to enact a fast idle. Below about -15C, I watch the coolant temp drop sitting at a stop light. Happened more so on my 2009 TDI than the 2015, but it still happens.

whizznbyu · Feb 26, 2021

Mike in Anchorage said:
Depends on the ambient temp. Which should probably be a part of the code to enact a fast idle. Below about -15C, I watch the coolant temp drop sitting at a stop light. Happened more so on my 2009 TDI than the 2015, but it still happens.

THAT is cold.

High idle when its cold.

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