S54 rough idling

soundofspeed · 10-01-2021, 07:16 PM

happened from one day to the next.
Was driving perfectly, wanted to start 5 days later. Rough start, lots of misfiring. Didn't recognize the secondary air pump.
Lot´s of error codes popped up:
2A00 - secondary air system
2D06 - DME: mass air system
2F65 - DME: brake booster system check
all the misfiring for the cylinder

it went better after the car got warm.
Cleard all the codaes, after warmup less codes showed up:
2D06 - DME: mass air system
2FDA - DME: crankcase ventilation, system check

and, after driving for a while,
2F65 - DME: brake booster system check

when disconnecting the HFM and the crankcase ventilation valve on top of th engine, the corrospondending electric error codes showed up.

Air fuel ratio adjustment is working. Car has power when driving, don't feel a difference.

With the autel system I was able to turn on the secondary air pump, so connections the the air pump seem to work.

Interesting observation:
When opening the oil filler cap, nothing changes, also AFR adaption doesn't change.
When driving, also mass air flow in kg/h doesn't change, stays constant at 1,1kg/h.

Have to check if secondary air pump starts when engine is cold.

Thanks for all ideas.

Michael9218 · 10-02-2021, 01:48 PM

Possibly the MAF?
Mine recently died on the track car. At first the symptoms were random and infrequent. Rough idle was definitely one of the symptoms.
Mine didn't throw any codes, but a lot of systems have been eliminated from the car and the ECU.

drocket77 · 10-04-2021, 08:46 AM

I would check MAF first, than O2 sensors. My car did this, as the previous owner had all the O2 sensors before the cat. I "kinda fixed it" with a spark anti fouler for the "rear" O2's. It never threw a code for the O2's, and would have random misfires with the exception of 1 of the cylinders(think it was #1). But now I still get a misfire every now and than, but only when I am at a lower speed with a low constant RPM. I plan on getting this fixed, but do not have an inspection for 1.5 more years. When I get time and more welding skill I will attempt to fix it.

wdb · 10-04-2021, 11:28 AM

Sounds like a vacuum leak.

soundofspeed · 10-09-2021, 05:12 PM

thank you all for the ideas.
Checked the MAF again, in the MAF only gives a constant value.
Drove to a friend with a Z4M, put in his MAF and it showed values.
Will order a new MAF now.

soundofspeed · 10-16-2021, 07:56 PM

put in a new MAF.

Works without problems now.

10-01-2021, 07:16 PM	#1
soundofspeed Enlisted Member 156 Rep 40 Posts Drives: E36 M3, E86 Z4M, E90 M3 Join Date: Feb 2020 Location: New York / Germany iTrader: (0)	S54 rough idling - many fault codes happened from one day to the next. Was driving perfectly, wanted to start 5 days later. Rough start, lots of misfiring. Didn't recognize the secondary air pump. Lot´s of error codes popped up: 2A00 - secondary air system 2D06 - DME: mass air system 2F65 - DME: brake booster system check all the misfiring for the cylinder it went better after the car got warm. Cleard all the codaes, after warmup less codes showed up: 2D06 - DME: mass air system 2FDA - DME: crankcase ventilation, system check and, after driving for a while, 2F65 - DME: brake booster system check when disconnecting the HFM and the crankcase ventilation valve on top of th engine, the corrospondending electric error codes showed up. Air fuel ratio adjustment is working. Car has power when driving, don't feel a difference. With the autel system I was able to turn on the secondary air pump, so connections the the air pump seem to work. Interesting observation: When opening the oil filler cap, nothing changes, also AFR adaption doesn't change. When driving, also mass air flow in kg/h doesn't change, stays constant at 1,1kg/h. Have to check if secondary air pump starts when engine is cold. Thanks for all ideas. Attached Images __________________
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10-02-2021, 01:48 PM	#2
Michael9218 Lieutenant 595 Rep 484 Posts Drives: 2007 Z4 M Coupe Join Date: Oct 2012 Location: Woodstock, GA iTrader: (0)	Possibly the MAF? Mine recently died on the track car. At first the symptoms were random and infrequent. Rough idle was definitely one of the symptoms. Mine didn't throw any codes, but a lot of systems have been eliminated from the car and the ECU.
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10-04-2021, 08:46 AM	#3
drocket77 Private 4 Rep 50 Posts Drives: 2004 BMW Z4 Join Date: Nov 2019 Location: Delaware iTrader: (0)	I would check MAF first, than O2 sensors. My car did this, as the previous owner had all the O2 sensors before the cat. I "kinda fixed it" with a spark anti fouler for the "rear" O2's. It never threw a code for the O2's, and would have random misfires with the exception of 1 of the cylinders(think it was #1). But now I still get a misfire every now and than, but only when I am at a lower speed with a low constant RPM. I plan on getting this fixed, but do not have an inspection for 1.5 more years. When I get time and more welding skill I will attempt to fix it.
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10-04-2021, 11:28 AM	#4
wdb dances with roads 4717 Rep 4,094 Posts Drives: '07 E86, '02 996, '95 Seven Join Date: Jul 2015 Location: the perimeter iTrader: (4)	Sounds like a vacuum leak.
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10-09-2021, 05:12 PM	#5
soundofspeed Enlisted Member 156 Rep 40 Posts Drives: E36 M3, E86 Z4M, E90 M3 Join Date: Feb 2020 Location: New York / Germany iTrader: (0)	thank you all for the ideas. Checked the MAF again, in the MAF only gives a constant value. Drove to a friend with a Z4M, put in his MAF and it showed values. Will order a new MAF now. __________________
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10-16-2021, 07:56 PM	#6
soundofspeed Enlisted Member 156 Rep 40 Posts Drives: E36 M3, E86 Z4M, E90 M3 Join Date: Feb 2020 Location: New York / Germany iTrader: (0)	put in a new MAF. Works without problems now. __________________
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