I'm a bit desperate as I've been having issues with my 2015 Q50 that are getting worse by the day. Here is the timeline of events which may or may not be related. The car is only 36K. I'm 46 but drive like I"m 96, so this car has been well kept. I change the oil every 6 months.

1 - About 2 weeks ago I replaced the 2 air filters, cabin filter and brake pads
2 - During the filter replacement, I noticed both enclosures where the air filters rest were not closing properly. I ordered these already.
3 - Days later I began having issues in the morning where the car would hesitate for a moment while going around 20-30 mph. Later it was fine and that was all. No noise, just some jerking.
4 - Progressively the car started making a strange noise in the morning and the hesitation/lagging got bigger. Now I need to drive the car for about 15 min before it goes back to normal
5 - No warning lights are showing up.
6 - I took the car to 2 mechanics, but their computer did not detect anything wrong.

Someone told me it could be a vacuum leak. Others tell me it could be Mass Flow Sensor or the Ignition coil packs causing a misfire. Another person told me it could be the fuel regulator and yet another the timing belt.

Can anyone please help me out by pointing me in the right direction? I will truly appreciate your comments.

The following video shows the engine and demonstrates the noise it makes

[/b]https://www.dropbox.com/s/fobgqqp2pe9ht ... e.mp4?dl=0

Click on the video link.

That sounds baaad , curiously with a rap-a tap like that people talking timing chain or VVT , possible -
mystery is you have not ONE mention of checking your actual oil level . That just goes along with any theory on those components failing.

Check oil level - REMOVE & examine oil filter & block's bypass check balls if has them , empty filter and "sift" for debris !

The enclosure problem/breakage ? Do you have those variable -runner intakes ? Could a piece of Crap have gotten inside snorkel ? blocking MAF's ? Getting sucked into crankcase somehow - blocking oil passages and ruining your top-end or rod bearings ? Look for plastic pieces in ALL ducting ahead AND behind MAF's . Look inside butterflys.

If you may - immediately hookup an oil pressure gauge - IDIOT LIGHT may NOT show ?? But remeber the pressure reading is USUALLY from only right after the filter/oil pump , and is NOT going to reveal upstream 'gallies' nor passages and orifices that may be STARVING oil pressure in a certain area that's destroying the motor

Don't rule out sabotage , "who doesn't love ya baby ?? " - KOJAK

I'm thinking something related to changing the filters, which would be MAF related.... but that should theoretically throw a code.

Go back through everything you did and double-check connections. Pull both battery cable connections for an hour and reinstall. Keep us posted, I'll link this to some other folks who might have some insight.

Good morning all.

Yeah, this thing baffles me. It was a guy who did the work, but I was there and he was very careful when he did all the work. I also think it's MAF related, but we'll see. Heading now to a new mechanic to see what they say. I'm new in this city, so I don't even know my next door neighbor; this makes it harder to get support.

Thank you all !! I will post an update here.

CL

Did anyone , this mechanic especially get to drive it by themselves where it's possible they "tested the car & motor to it's limits" , and motor cold & not warmed up well ?? It just sounds so mechanical / grinding in nature like s t r e t c h e d timing chain flapping - whatever. Does'nt really sound 'running problem' due to glitch as much , hate to say.

Like there's horror stories of the 'Ex' taking the car late at night - beating the hell out of it - returned quietly , not to get too personal , but if that's why you are recently in a new environment AND are not able to garage your car . They'll take and drop 6-32 nuts into your upper head via oil filler too Doin' the valvetrain boogy.

macgiver wrote: ↑

Fri Sep 27, 2019 8:26 pm

That sounds baaad , curiously with a rap-a tap like that people talking timing chain or VVT , possible -
mystery is you have not ONE mention of checking your actual oil level . That just goes along with any theory on those components failing.

Check oil level - REMOVE & examine oil filter & block's bypass check balls if has them , empty filter and "sift" for debris !

The enclosure problem/breakage ? Do you have those variable -runner intakes ? Could a piece of Crap have gotten inside snorkel ? blocking MAF's ? Getting sucked into crankcase somehow - blocking oil passages and ruining your top-end or rod bearings ? Look for plastic pieces in ALL ducting ahead AND behind MAF's . Look inside butterflys.

If you may - immediately hookup an oil pressure gauge - IDIOT LIGHT may NOT show ?? But remeber the pressure reading is USUALLY from only right after the filter/oil pump , and is NOT going to reveal upstream 'gallies' nor passages and orifices that may be STARVING oil pressure in a certain area that's destroying the motor

Don't rule out sabotage , "who doesn't love ya baby ?? " - KOJAK

Hello macgiver,

Well your hypothesis has been confirmed and it became the "macgiver Theory of oil inspection."

Problem Solved:

So, I took the car to a nearby mechanic and left it there overnight so they could check the noise in the morning. 3 hours later the guy calls me and tells me that I had almost no oil in the engine. The drain plug was loose and it was leaking oil in small amounts. So, at the end it was not related at all to the air filter change or the PVC valve replacement, but rather a low oil that was causing the clapping noise until the pressure increased when the car warmed up.

Anyhow, I'm really happy that I found this forum and a trustworthy mechanic. He only charged me $25 bucks for the oil change. Can't beat that !!

Thank you all !!

But I so detest censorship from one of the moderators

carloslijeron wrote: ↑

Mon Sep 30, 2019 4:59 pm

Hello macgiver,

Well your hypothesis has been confirmed and it became the "macgiver Theory of oil inspection."

Problem Solved:

So, I took the car to a nearby mechanic and left it there overnight so they could check the noise in the morning. 3 hours later the guy calls me and tells me that I had almost no oil in the engine. The drain plug was loose and it was leaking oil in small amounts. So, at the end it was not related at all to the air filter change or the PVC valve replacement, but rather a low oil that was causing the clapping noise until the pressure increased when the car warmed up.

Anyhow, I'm really happy that I found this forum and a trustworthy mechanic. He only charged me $25 bucks for the oil change. Can't beat that !!

Thank you all !!

Interesting....I would have thought the multiple mechanics working on it would have noticed the oil under the vehicle. Granted, the bottom of the engine has a cover but if you were low enough on oil where the top of the motor was running dry you should have seen something underneath and dripping on the ground after it sat overnight.

Hopefully there is no driveline problems in the future due to this issue.