Just changed Valve Cover gasket. Now SES light on with rough idle

LiveLikeKure · 12-23-2020, 12:26 AM

Hello all,

So i have a 2013 Bmw128i that recently had the good ol VCG leak. I took it to my local mechanic and he just changed the VCG and spark plugs as of yesterday.

As I turn on the car, I immediately notice the service engine soon light was on(which was never on before) and there is a pretty rough idle that jumps up to about 1000 RPM before dropping back down to about 500 RPM.
My mechanic said he pulled the codes and it came back as a faulty mass air flow sensor. Now after looking up the symptoms it does appear to be in line with a faulty MAF but I NEVER had any issues with it prior to taking in my car for the VCG and spark plug change.

The car seems to be driving fine, actually smoother than usual, until im idling. Then the engine kind of starts to bog down and feel like it may stall at any moment.

Any ideas on what it could be? Is it strange these issues appeared right after my mechanic did the repairs? Its just frustrating to have one issue fixed while creating another.

Any advice here would be appreciated, Thanks!

Thunderguts · 12-23-2020, 09:25 AM

Given what a PITA it is to replace the valve cover, I'm guessing he unplugged something and forgot to plug it back in.

b1aze · 12-23-2020, 10:42 AM

Eccentric shaft sensor? Is it manual or automatic?

Thunderguts · 12-23-2020, 11:08 AM

Maybe a broken breather hose? I would think that could cause a lumpy idle.

They break if you breathe on them. It might literally combust if you said a cross word in its vicinity.

Lester · 12-23-2020, 11:19 AM

Your car is at the age where stuff like this will happen. You get one thing fixed, then something else pops up, shortly after.

I had the water pump replaced under extended warranty on my 135, and a few weeks later one of the small water hoses near the block started to leak. What can you do?

It is probably the MAF - but rough idle can also be dirty VANOS or even a bad tank of gasoline.

A month or so ago, I impulsively filled up with 1/2 tank of discount 91 Octane gasoline, the next day I started getting misfire codes on cyl 1 and 6. The car ran rough until it warmed up, similar to your rough idle. It ran fine after a few minutes, so I cleared the codes and kept an eye on things.

After a few fill ups with Chevron Techron 94 Octane, it went back to normal again. No start up codes, and running smooth as silk.

dtla1 · 12-23-2020, 12:20 PM

I would have them triple check to make sure everything was re-plugged in correctly.

I recently had an issue where I took my car in to get some sounds diagnosed including rear suspension. The well known and usually recommended BMW specific shop to me forgot to plug back in one of the two connectors in each taillight and I had been driving around thinking the light error I had on my dash was for bad (non Can Bus or whatever it's called) interior LED lights I had installed a few weeks prior to visiting that shop. Finally pulled the codes after replacing my interior lights with better can bus lights and it was taillights. Opened the access panel in the carpet and finally noticed the outside connectors weren't plugged in.

Always, re-check everything and make sure nothing is disconnected. Could also just need to clean the sensor.

LiveLikeKure · 12-23-2020, 03:56 PM

Quote:

Originally Posted by Thunderguts

Given what a PITA it is to replace the valve cover, I'm guessing he unplugged something and forgot to plug it back in.

Thats kinda what it seems like. I dropped it back to him this morning and considering i havent heard a word since I'm thinking hes having a tough time figuring it out

LiveLikeKure · 12-23-2020, 04:00 PM

Quote:

Originally Posted by b1aze

Eccentric shaft sensor? Is it manual or automatic?

Its an automatic

Quote:

Originally Posted by Thunderguts

Maybe a broken breather hose? I would think that could cause a lumpy idle.
They break if you breathe on them. It might literally combust if you said a cross word in its vicinity.

Thanks, Ill throw that out there to him

Quote:

Originally Posted by Lester

Your car is at the age where stuff like this will happen. You get one thing fixed, then something else pops up, shortly after.

I had the water pump replaced under extended warranty on my 135, and a few weeks later one of the small water hoses near the block started to leak. What can you do?

It is probably the MAF - but rough idle can also be dirty VANOS or even a bad tank of gasoline.

A month or so ago, I impulsively filled up with 1/2 tank of discount 91 Octane gasoline, the next day I started getting misfire codes on cyl 1 and 6. The car ran rough until it warmed up, similar to your rough idle. It ran fine after a few minutes, so I cleared the codes and kept an eye on things.

After a few fill ups with Chevron Techron 94 Octane, it went back to normal again. No start up codes, and running smooth as silk.

Yeah i hear that but i dont think thats it cause this issue literally started the second i got the car back from him after the VCG repair. It was perfectly fine when i dropped it to him. Hell the car was actually driving great prior to the repair, I just wanted to get a head of the game and take care of the leak before it got worse

Quote:

Originally Posted by dtla1

I would have them triple check to make sure everything was re-plugged in correctly.

I recently had an issue where I took my car in to get some sounds diagnosed including rear suspension. The well known and usually recommended BMW specific shop to me forgot to plug back in one of the two connectors in each taillight and I had been driving around thinking the light error I had on my dash was for bad (non Can Bus or whatever it's called) interior LED lights I had installed a few weeks prior to visiting that shop. Finally pulled the codes after replacing my interior lights with better can bus lights and it was taillights. Opened the access panel in the carpet and finally noticed the outside connectors weren't plugged in.

Always, re-check everything and make sure nothing is disconnected. Could also just need to clean the sensor.

Man these cars are so complicated.

LiveLikeKure · 12-23-2020, 05:01 PM

Now the mechanic is saying cylinder 1 and 3 are misfiring. He also changed the spark plugs yesterday as well.

Was not having any of these issues before he started the VCG repair.

I feel like the car is in worse shape now than before i brought it to him smh

2008e92328i · 12-29-2020, 02:23 AM

Quote:

Originally Posted by LiveLikeKure

Now the mechanic is saying cylinder 1 and 3 are misfiring. He also changed the spark plugs yesterday as well.

Was not having any of these issues before he started the VCG repair.

I feel like the car is in worse shape now than before i brought it to him smh

Quote:

Originally Posted by LiveLikeKure

Now the mechanic is saying cylinder 1 and 3 are misfiring. He also changed the spark plugs yesterday as well.

Was not having any of these issues before he started the VCG repair.

I feel like the car is in worse shape now than before i brought it to him smh

He needs to fix it. I'm afraid to think that he messed something up. I hope you'll get your car back soon in good or better condition than it was before. Let us know the outcome

dtla1 · 12-29-2020, 11:53 AM

Quote:

Originally Posted by LiveLikeKure

Now the mechanic is saying cylinder 1 and 3 are misfiring. He also changed the spark plugs yesterday as well.

Was not having any of these issues before he started the VCG repair.

I feel like the car is in worse shape now than before i brought it to him smh

Curious what the spark plugs looked like? It possible oil either got on them and spoiled them, or maybe the ignition coils weren't plugged in correctly. It's so hard to diagnose these things without pictures, videos, etc. honestly. Just kinda shooting at random theories here.

MightyMouseTech · 12-29-2020, 12:14 PM

Really doubt it is the MAF sensor. Sounds like there is a vacuum leak, which would also explain the misfire in cylinders 1-3. First thing to do is a smoke test. Good chance there is a leak for the breather hose where it connects to the back of the valve cover. That hose would have had to be removed when removing the valve cover, and it will be very brittle.

The valve covers also tend to crack when being removed or installed. This is why we never replace just the gasket.

Do you have the list of the exact faults? Probably air mass faults?

Thunderguts · 12-29-2020, 05:30 PM

Quote:

Originally Posted by MightyMouseTech

Good chance there is a leak for the breather hose where it connects to the back of the valve cover. That hose would have had to be removed when removing the valve cover, and it will be very brittle.

Can confirm! I literally broke mine brushing against it.

gds52 · 12-29-2020, 11:21 PM

With all the great suggestions, ask your mechanic to check if he loosened and then tightened the ground connection or not.
Not sure If he needed to even touch it for this repair, but just in case.
This is located on the right front wheel well area.

12-23-2020, 12:26 AM	#1
LiveLikeKure New Member 4 Rep 17 Posts Drives: Bmw 128i Join Date: Sep 2019 Location: Florida iTrader: (0)	Just changed Valve Cover gasket. Now SES light on with rough idle Hello all, So i have a 2013 Bmw128i that recently had the good ol VCG leak. I took it to my local mechanic and he just changed the VCG and spark plugs as of yesterday. As I turn on the car, I immediately notice the service engine soon light was on(which was never on before) and there is a pretty rough idle that jumps up to about 1000 RPM before dropping back down to about 500 RPM. My mechanic said he pulled the codes and it came back as a faulty mass air flow sensor. Now after looking up the symptoms it does appear to be in line with a faulty MAF but I NEVER had any issues with it prior to taking in my car for the VCG and spark plug change. The car seems to be driving fine, actually smoother than usual, until im idling. Then the engine kind of starts to bog down and feel like it may stall at any moment. Any ideas on what it could be? Is it strange these issues appeared right after my mechanic did the repairs? Its just frustrating to have one issue fixed while creating another. Any advice here would be appreciated, Thanks!
	Appreciate 0 Tweet Quote

12-23-2020, 09:25 AM	#2
Thunderguts Major 785 Rep 1,000 Posts Drives: 2009 128i Sport MT Join Date: Jul 2018 Location: DFW iTrader: (0)	Given what a PITA it is to replace the valve cover, I'm guessing he unplugged something and forgot to plug it back in. __________________ Official BMWP Whore - BMWP suspension kit w/ M3 arms, BMWP big brake kit, BMWP intake w/Mishimoto tube, BMWP exhaust, BMWP carbon strut brace, BMWP short shifter, and BMWP carbon spoiler. OZ Leggera HLT w/ 245 square setup.
	Appreciate 0 Quote

12-23-2020, 10:42 AM	#3
b1aze Just one more taste... 566 Rep 2,011 Posts Drives: 2013 128i 6MT MSport Join Date: Aug 2012 Location: Uxbridge MA iTrader: (18)	Eccentric shaft sensor? Is it manual or automatic? __________________ My Build Thread: Jet Black 6MT 128i with MSport
	Appreciate 0 Quote

12-23-2020, 11:08 AM	#4
Thunderguts Major 785 Rep 1,000 Posts Drives: 2009 128i Sport MT Join Date: Jul 2018 Location: DFW iTrader: (0)	Maybe a broken breather hose? I would think that could cause a lumpy idle. They break if you breathe on them. It might literally combust if you said a cross word in its vicinity. __________________ Official BMWP Whore - BMWP suspension kit w/ M3 arms, BMWP big brake kit, BMWP intake w/Mishimoto tube, BMWP exhaust, BMWP carbon strut brace, BMWP short shifter, and BMWP carbon spoiler. OZ Leggera HLT w/ 245 square setup.
	Appreciate 0 Quote

12-23-2020, 11:19 AM	#5
Lester Brigadier General 295 Rep 3,350 Posts Drives: Join Date: Oct 2007 iTrader: (0)	Your car is at the age where stuff like this will happen. You get one thing fixed, then something else pops up, shortly after. I had the water pump replaced under extended warranty on my 135, and a few weeks later one of the small water hoses near the block started to leak. What can you do? It is probably the MAF - but rough idle can also be dirty VANOS or even a bad tank of gasoline. A month or so ago, I impulsively filled up with 1/2 tank of discount 91 Octane gasoline, the next day I started getting misfire codes on cyl 1 and 6. The car ran rough until it warmed up, similar to your rough idle. It ran fine after a few minutes, so I cleared the codes and kept an eye on things. After a few fill ups with Chevron Techron 94 Octane, it went back to normal again. No start up codes, and running smooth as silk. __________________ 2008 135i, Jet Black, 6 spd, Canadian Sport package, black leatherette, manual seats, aluminum glacier trim, PDC. 1983 E21 Delphin, M10, 5 speed, LSD, MSW wheels, recaro seats, Hartge strut brace, rear sway bar. [SIGPIC][/SIGPIC]
	Appreciate 0 Quote

12-23-2020, 12:20 PM	#6
dtla1 Colonel 828 Rep 2,232 Posts Drives: 2011 135i, Space Grey Join Date: Apr 2014 Location: Silicon Valley iTrader: (2)	I would have them triple check to make sure everything was re-plugged in correctly. I recently had an issue where I took my car in to get some sounds diagnosed including rear suspension. The well known and usually recommended BMW specific shop to me forgot to plug back in one of the two connectors in each taillight and I had been driving around thinking the light error I had on my dash was for bad (non Can Bus or whatever it's called) interior LED lights I had installed a few weeks prior to visiting that shop. Finally pulled the codes after replacing my interior lights with better can bus lights and it was taillights. Opened the access panel in the carpet and finally noticed the outside connectors weren't plugged in. Always, re-check everything and make sure nothing is disconnected. Could also just need to clean the sensor.
	Appreciate 0 Quote

12-23-2020, 05:01 PM	#9
LiveLikeKure New Member 4 Rep 17 Posts Drives: Bmw 128i Join Date: Sep 2019 Location: Florida iTrader: (0)	Now the mechanic is saying cylinder 1 and 3 are misfiring. He also changed the spark plugs yesterday as well. Was not having any of these issues before he started the VCG repair. I feel like the car is in worse shape now than before i brought it to him smh
	Appreciate 0 Quote

12-29-2020, 12:14 PM	#12
MightyMouseTech Major General 4338 Rep 6,196 Posts Drives: 13 135i 6MT LeMans Blue MSport Join Date: Feb 2013 Location: Ottawa, Canada iTrader: (0)	Really doubt it is the MAF sensor. Sounds like there is a vacuum leak, which would also explain the misfire in cylinders 1-3. First thing to do is a smoke test. Good chance there is a leak for the breather hose where it connects to the back of the valve cover. That hose would have had to be removed when removing the valve cover, and it will be very brittle. The valve covers also tend to crack when being removed or installed. This is why we never replace just the gasket. Do you have the list of the exact faults? Probably air mass faults?
	Appreciate 0 Quote

12-29-2020, 11:21 PM	#14
gds52 Colonel 886 Rep 2,720 Posts Drives: BMW Z4M Coupe, BMW 328i E93 Co Join Date: Oct 2011 Location: NJ iTrader: (0)	With all the great suggestions, ask your mechanic to check if he loosened and then tightened the ground connection or not. Not sure If he needed to even touch it for this repair, but just in case. This is located on the right front wheel well area.
	Appreciate 0 Quote