Erratic Idle & No Start/Stop

Evil Derboy · 09-15-2017, 02:48 AM

Hi all,

Car is booked into to my local dealer for 2nd of October to look into this but wondered if anyone else has experienced the same problem.

Cold start sequence works fine but when the engine is warmed up, when stationery in traffic or at lights etc. the RPM is erratically dancing around to the tune of 300pm. I can also feel non-linear vibration through the seat - nothing major but its not exactly purring like a kitten.

The car also refuses to stop the engine as per the normal stop/start programme.

There are no warning messages or warning lights in the iDrive or in the instrument cluster.

Anyone have any experience with this?

Evil Derboy · 09-15-2017, 10:08 AM

Weird. This seems to have sorted itself today.

upstate650 · 09-15-2017, 10:42 AM

Quote:

Originally Posted by Derboy

Weird. This seems to have sorted itself today.

Keep your appointment. Immediate suspect would be vacuum lines, plugs, coils, injectors, which can act up intermittently.

Could be something as simple as bad gas. If it was me, I would go there unannounced now and make them pull the codes. They could self clear by the time you get in there if you wait for your appointment.

Evil Derboy · 09-15-2017, 10:55 AM

Definitely keeping the appointment. I've already scanned it for codes and there are no DTCs. Looks like the Airflow is erratic even when stationery. I'm going clean the MAF Sensors and see if that makes a difference. Start Stop is working fine so maybe a red herring there. Will still take the car in fro them to check it out to be safe.

Evil Derboy · 09-15-2017, 11:05 AM

First MAF out and it has oil residue right on the sensor contacts.

Evil Derboy · 09-15-2017, 12:55 PM

So second MAF was clean but I sprayed it down anyway. After putting everything back together and a quick Italian tune-up everything is fine. There is still almost imperceptible fluctuation wth the rev needle but no longer any feel through the seat.

I'll keep the appointment as it's 2 weeks away so will see how it goes.

Flying Ace · 09-15-2017, 02:25 PM

does the car have an idle air control valve?

BMWRog · 09-15-2017, 02:34 PM

What mileage are you at right now? And when was last service done?

Evil Derboy · 09-15-2017, 04:18 PM

Quote:

Originally Posted by Flying Ace

does the car have an idle air control valve?

No idea.

Evil Derboy · 09-15-2017, 04:19 PM

Quote:

Originally Posted by BMWRog

What mileage are you at right now? And when was last service done?

32k miles. Last service was January.

Flying Ace · 09-15-2017, 04:44 PM

my point is, if the car has an idle air control valve (my M3 has it), then that valve can get gunked up or become faulty and it'll mess up the idle.

Evil Derboy · 09-15-2017, 04:47 PM

Quote:

Originally Posted by Flying Ace

my point is, if the car has an idle air control valve (my M3 has it), then that valve can get gunked up or become faulty and it'll mess up the idle.

Makes sense but I've no idea if this engine has one. Assume it has if the M3 does.

Flying Ace · 09-15-2017, 04:50 PM

Quote:

Originally Posted by Derboy

Makes sense but I've no idea if this engine has one. Assume it has if the M3 does.

usually, there's some type of mechanical device that operates to the effect of an idle air control valve. It's often called different names:

idle air control valve
idle control valve

It works with the MAF or other air sensors to tell the car how much fuel it needs to inject given what your throttle position is (idle, accelerate, cruise, decelerate.) Basically it prevents your car from stalling when idling, decelerating or cruising and ensure proper power delivery when you accelerate.

Evil Derboy · 09-16-2017, 03:54 AM

So car is back to running perfect after taking it another run this morning. Looks like the oil on the left hand MAF was the culprit. Think I'll keep my dealer appointment in case it comes back but if not I'll cancel it. They'll only say they can't replicate it anyway.

Interestingly I've been in touch with the previous owner and said that this is a fairly oil-thirsty car.

BMWRog · 09-16-2017, 11:40 AM

Quote:

Originally Posted by Derboy

Interestingly I've been in touch with the previous owner and said that this is a fairly oil-thirsty car.

Out of interest, at what mileage are you topping up with oil, and how much? I know there's another poster on this forum who gets a ludicrously low miles-per-pint...

Evil Derboy · 09-17-2017, 01:14 AM

Quote:

Originally Posted by BMWRog

Out of interest, at what mileage are you topping up with oil, and how much? I know there's another poster on this forum who gets a ludicrously low miles-per-pint...

I've not had to put any in it but I've only owned it for about 6 weeks. I've done Round 800 miles so far.

BMWRog · 09-17-2017, 03:58 AM

Quote:

Originally Posted by Derboy

I've not had to put any in it but I've only owned it for about 6 weeks. I've done Round 800 miles so far.

So I take it you've been checking the 'Vehicle Status', 'Engine Oil Level' since there's no longer a dipstick. Never had to put any oil in mine, as it always seems to indicate 'full'. I just wonder how accurate this is?

I admit I was slightly taken aback at the time I bought the car (a BMW AUC), when the sales guy put a fresh litre pack of oil in the boot with the user manual and the wind deflector!

Pure Adrenaline · 11-11-2017, 09:48 PM

My 2014 M6 GC went in for this issue. They didn't find any codes; they just updated the engine mgmt software. It's still revving up and down at idle.

The SA said it's probably gas (Costco premium) and to try Chevron. But it only started doing this a few months ago and I've always put the same gas in. But I guess I'll give Chevron a try; if it doesn't, she's going back in and I'm going to ask them to check the MAF sensors for oil.

gregmb · 11-12-2017, 10:21 AM

Quote:

Originally Posted by Pure Adrenaline

My 2014 M6 GC went in for this issue. They didn't find any codes; they just updated the engine mgmt software. It's still revving up and down at idle.

The SA said it's probably gas (Costco premium) and to try Chevron. But it only started doing this a few months ago and I've always put the same gas in. But I guess I'll give Chevron a try; if it doesn't, she's going back in and I'm going to ask them to check the MAF sensors for oil.

It might be the gas but who knows - I've been using Costco premium for the last decade on my cars and never had gas problems (they maintain a Top Tier rating which is legit). I also drop in a Techron treatment every 5-10 tanks but that probably just makes me feel better

09-15-2017, 02:48 AM	#1
Evil Derboy Lieutenant 271 Rep 425 Posts Drives: E92 M3 Join Date: Aug 2017 Location: . iTrader: (0)	Erratic Idle & No Start/Stop Hi all, Car is booked into to my local dealer for 2nd of October to look into this but wondered if anyone else has experienced the same problem. Cold start sequence works fine but when the engine is warmed up, when stationery in traffic or at lights etc. the RPM is erratically dancing around to the tune of 300pm. I can also feel non-linear vibration through the seat - nothing major but its not exactly purring like a kitten. The car also refuses to stop the engine as per the normal stop/start programme. There are no warning messages or warning lights in the iDrive or in the instrument cluster. Anyone have any experience with this? Last edited by Evil Derboy; 09-15-2017 at 02:57 AM..
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09-15-2017, 10:08 AM	#2
Evil Derboy Lieutenant 271 Rep 425 Posts Drives: E92 M3 Join Date: Aug 2017 Location: . iTrader: (0)	Weird. This seems to have sorted itself today.
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09-15-2017, 10:55 AM	#4
Evil Derboy Lieutenant 271 Rep 425 Posts Drives: E92 M3 Join Date: Aug 2017 Location: . iTrader: (0)	Definitely keeping the appointment. I've already scanned it for codes and there are no DTCs. Looks like the Airflow is erratic even when stationery. I'm going clean the MAF Sensors and see if that makes a difference. Start Stop is working fine so maybe a red herring there. Will still take the car in fro them to check it out to be safe.
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09-15-2017, 11:05 AM	#5
Evil Derboy Lieutenant 271 Rep 425 Posts Drives: E92 M3 Join Date: Aug 2017 Location: . iTrader: (0)	First MAF out and it has oil residue right on the sensor contacts.
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09-15-2017, 12:55 PM	#6
Evil Derboy Lieutenant 271 Rep 425 Posts Drives: E92 M3 Join Date: Aug 2017 Location: . iTrader: (0)	So second MAF was clean but I sprayed it down anyway. After putting everything back together and a quick Italian tune-up everything is fine. There is still almost imperceptible fluctuation wth the rev needle but no longer any feel through the seat. I'll keep the appointment as it's 2 weeks away so will see how it goes.
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09-15-2017, 02:25 PM	#7
Flying Ace Lieutenant General 4985 Rep 11,891 Posts Drives: G05 45e, 997.1 & 991.1 GT3s Join Date: Jul 2014 Location: SF, CA iTrader: (5)	does the car have an idle air control valve? __________________ 22 Phytonic/Coffee X5 45e (CoVID-free) 08 Speed Yellow 911 GT3 Sharkwerks 12 AW/Cinnamon X5d Sports Pkg (retired) 14 AW/Beige M6GC ZCP, MPE, V2 steering wheel, vorsteiner (retired) 08 SSII/Black E90 M3 (retired)
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09-15-2017, 02:34 PM	#8
BMWRog Private First Class 19 Rep 126 Posts Drives: 2014 M6 Convertible Join Date: Feb 2017 Location: Oxfordshire, U.K. iTrader: (0)	What mileage are you at right now? And when was last service done?
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09-15-2017, 04:44 PM	#11
Flying Ace Lieutenant General 4985 Rep 11,891 Posts Drives: G05 45e, 997.1 & 991.1 GT3s Join Date: Jul 2014 Location: SF, CA iTrader: (5)	my point is, if the car has an idle air control valve (my M3 has it), then that valve can get gunked up or become faulty and it'll mess up the idle. __________________ 22 Phytonic/Coffee X5 45e (CoVID-free) 08 Speed Yellow 911 GT3 Sharkwerks 12 AW/Cinnamon X5d Sports Pkg (retired) 14 AW/Beige M6GC ZCP, MPE, V2 steering wheel, vorsteiner (retired) 08 SSII/Black E90 M3 (retired)
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09-16-2017, 03:54 AM	#14
Evil Derboy Lieutenant 271 Rep 425 Posts Drives: E92 M3 Join Date: Aug 2017 Location: . iTrader: (0)	So car is back to running perfect after taking it another run this morning. Looks like the oil on the left hand MAF was the culprit. Think I'll keep my dealer appointment in case it comes back but if not I'll cancel it. They'll only say they can't replicate it anyway. Interestingly I've been in touch with the previous owner and said that this is a fairly oil-thirsty car.
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11-11-2017, 09:48 PM	#18
Pure Adrenaline New Member 2 Rep 19 Posts Drives: 2014 M6 GC CP Join Date: May 2017 Location: Mill Creek, WA iTrader: (0)	My 2014 M6 GC went in for this issue. They didn't find any codes; they just updated the engine mgmt software. It's still revving up and down at idle. The SA said it's probably gas (Costco premium) and to try Chevron. But it only started doing this a few months ago and I've always put the same gas in. But I guess I'll give Chevron a try; if it doesn't, she's going back in and I'm going to ask them to check the MAF sensors for oil.
	Appreciate 0 Quote