5th Gen Subaru Impreza Forum banner
1 - 20 of 20 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter · #1 ·
Do all of these sound like a diesel lawn tractor on cold-start? And by cold start I mean just not started in awhile...it's in a 70°F garage. Settles down to what I would call normal once shifted to drive, but it really revs and sounds quite unflattering at first start.
 

·
Registered
Joined
·
132 Posts
yes definitely. there's a little blue light on the dash to let you know when its cold also it idles real high until its warmed up. I let it get to operating temp before driving. Normal safety feature thing for sure.
 

·
Registered
Joined
·
525 Posts
Subaru opposed-piston engines have traditionally been more 'noisy' than other engine-designs....especially when started cold. Lets not forget there are TWICE the number of camshafts than inline engines. Also, the exhaust heat-shield has a tendency to rattle at specific RPMs.
 

·
Premium Member
2017 Mazda CX-5 Sport
Joined
·
2,187 Posts
Do all of these sound like a diesel lawn tractor on cold-start? And by cold start I mean just not started in awhile...it's in a 70°F garage. Settles down to what I would call normal once shifted to drive, but it really revs and sounds quite unflattering at first start.
Is this your first flat four?
 

·
Registered
2018 Sport Hatch 5-Speed Manual
Joined
·
208 Posts
I know this is an older post but I wanted to comment on this as I have noticed the same thing about my 18' Sport.

When I start it either in the morning or when I leave for work, it sounds very different. Louder, rougher, etc for about thirty seconds and then the RPM's drop and quiets way down. I also noticed this watching some videos of people showing their axleback exhausts.

I have to imagine this is some kind of emissions thing, maybe to the the cat to light off faster or to reduce cold start emissions until the cat lights off?
 

·
Registered
Joined
·
525 Posts
... I have to imagine this is some kind of emissions thing, maybe to the the cat to light off faster or to reduce cold start emissions until the cat lights off?
YES! The computer changes valve-timing and other criteria when engine is cold. Some of it is for emissions... some of it is to improve throttle-response on cold engine.

In the end - it is normal and nothing to worry about.
 

·
Registered
Joined
·
37 Posts
When discussing engines, "cold" simply means below operating temperature. Echoing some of what others have said, a high, loud, or rough idle when cold is common on newer vehicles, not just Subarus. This is done in part to reduce emissions by getting the catalyst heated quickly.

This isn't directly related to the question about high idle, but related to starting in general, as a matter of practice, it is a good idea to turn off accessories (A/C, headlights, heated seats ...) when starting (easier on the alternator and battery) and give your engine maybe 30 seconds to "get the juices flowing" before taking off (ensures proper lubrication). I use that time to plug in my phone.
 

·
Registered
2018 Sport Hatch 5-Speed Manual
Joined
·
208 Posts
I have a Scan Gauge II connected to the car at all times and I decided to view the ignition timing. Something interesting that I discovered is that the car is RETARDING the timing after start up. Mine started at -8 degrees retarded and went to -14 degrees retarded. Around 30-40 seconds, the idle smooths out and gets quieter. At that exact moment, the timing moved quickly to 20 degrees ADVANCED. I believe this is the main reason for the lounder sound and roughness in the idle.

I also discovered that it still does this on hot starts too, but I don't think it's as noticeable on a hot engine.
 

·
Registered
Joined
·
1 Posts
Do all of these sound like a diesel lawn tractor on cold-start? And by cold start I mean just not started in awhile...it's in a 70°F garage. Settles down to what I would call normal once shifted to drive, but it really revs and sounds quite unflattering at first start.
I purchased a 2019 Impreza with 2250kms from the dealer. They told me it did not need a service until 12400kms or 12 months. I am 50yo & work on my own cars so after hearing it cold start at the dealers, I knew the first thing I was doing was changing the oil & filter. Thank goodness I did. It was black & appeared to be a generic quality. I put a good oil filter on (removing the factory filter requires a good quality tool as super tight from new) and I put in 4.5 litres of Penrite HPR 0w30 - synthetic. The sump plug is also on super tight, use a short extension tool on your ratchet. After replacing the oil with best quality synthetic 0w30, the Impreza is much quieter on cold start and runs a few degrees cooler once up to operating temp. So my tip is to change oil & filter every 3-4000 miles, without fail. Subarus have tight tolerances and small oil galleries hence the oil specified. Allow them to warm up for at least 10 minutes normal driving before exceeding 4000 rpm and sit in driveway at cold start for at least 45 seconds to allow oil to flow & warm a little. If you use Subaru to service your car, tell them NOT to do the oil or provide it yourself. This practice will ensure your Subarus engine will last its lifetime.
 

·
Registered
Joined
·
126 Posts
I find this car has a very high cold idle before it settles down to a more normal level. It doesn't sound louder to me than other cars I've owned, just a higher cold idle level.
 

·
Registered
Joined
·
368 Posts
It's normal, we've had 6 Subarus and they all sounded like an old Volkswagon or Porsche 911 when cold. I've noticed flat engines sound like this when cold.
 

·
Registered
Joined
·
142 Posts
The Boxer in my new 2019 Inpreza is very Mechanical sounding, and it jas less than 2k mikes on this car.
I compare the mechanical boxer sound to Harley, lots of noise.
 

·
Registered
Joined
·
6 Posts
Hi all,

I appreciate all your comments. I am new to Subaru myself, just bought a new 2021 Impreza and was surprised at how loud it was when first starting. It then settles into a nice purr. I just wanted to ask if a slight vibration is also normal for the engine when it's running cold in the morning. You can feel the vibration in the car and you can also notice it under the hood. My wife, of course thinks I am obsessing.

Part of this doubt might come from the fact that this is my first car from a dealer. Not to go off on a tangent, but, at least here in the US, boy what a terrible experience it is to deal with car dealers! (A joke for lawyers flipped to apply to dealers: it's not that all dealers are bad. It's just that the 99% give a bad name to the other 1%.)

Thanks!
 

·
Registered
Joined
·
142 Posts
Hi all,

I appreciate all your comments. I am new to Subaru myself, just bought a new 2021 Impreza and was surprised at how loud it was when first starting. It then settles into a nice purr. I just wanted to ask if a slight vibration is also normal for the engine when it's running cold in the morning. You can feel the vibration in the car and you can also notice it under the hood. My wife, of course thinks I am obsessing.

Part of this doubt might come from the fact that this is my first car from a dealer. Not to go off on a tangent, but, at least here in the US, boy what a terrible experience it is to deal with car dealers! (A joke for lawyers flipped to apply to dealers: it's not that all dealers are bad. It's just that the 99% give a bad name to the other 1%.)

Thanks!
My Impreza is also my first Subaru...

Boxer engines are very mechanical sounding...
You Subaru will be louder than a Toyota corolla, it's the nature of the beast.

I love it
 

·
Registered
Joined
·
6 Posts
My Impreza is also my first Subaru...

Boxer engines are very mechanical sounding...
You Subaru will be louder than a Toyota corolla, it's the nature of the beast.

I love it
My Impreza is also my first Subaru...

Boxer engines are very mechanical sounding...
You Subaru will be louder than a Toyota corolla, it's the nature of the beast.

I love it
Hi Thomas,

Thank you for your reply. Does your engine also vibrate a bit when cold?
 

·
Registered
Joined
·
1 Posts
I purchased a 2019 Impreza with 2250kms from the dealer. They told me it did not need a service until 12400kms or 12 months. I am 50yo & work on my own cars so after hearing it cold start at the dealers, I knew the first thing I was doing was changing the oil & filter. Thank goodness I did. It was black & appeared to be a generic quality. I put a good oil filter on (removing the factory filter requires a good quality tool as super tight from new) and I put in 4.5 litres of Penrite HPR 0w30 - synthetic. The sump plug is also on super tight, use a short extension tool on your ratchet. After replacing the oil with best quality synthetic 0w30, the Impreza is much quieter on cold start and runs a few degrees cooler once up to operating temp. So my tip is to change oil & filter every 3-4000 miles, without fail. Subarus have tight tolerances and small oil galleries hence the oil specified. Allow them to warm up for at least 10 minutes normal driving before exceeding 4000 rpm and sit in driveway at cold start for at least 45 seconds to allow oil to flow & warm a little. If you use Subaru to service your car, tell them NOT to do the oil or provide it yourself. This practice will ensure your Subarus engine will last its lifetime.
I use 5w40 on my 2013 impreza that came with 160k kms changed from the black stuff that came with the car from Japan... my cold start is much better and car runs smooth... I am in tropical Africa.
 
1 - 20 of 20 Posts
Top