[NavyBurch]

I got the first oil change about 3 days ago. Was at 6,493 miles. Went to a Valvoline instant oil change facility. Got the MaxLife Synthetic blend and a tire rotation. After the oil change my car has a deeper "growl" when accelerating at low RPM. The car didn't do this before. It sounds like I added an aftermarket intake but it's bone stock. Acceleration is poor under around 3,200 RPM (which is normal?) but I can't tell any difference in power. I don't think it's an exhaust leak either. I checked and listed to different areas and all looks and sounds well. There is no ticking or knocking. Oil level is fine.

Any ideas as to what would change the noise? I can post a video trying to catch the noise if need be.

 

[Tigeo]

My guess is they pulled the air filter per their SOPs and didn't get in right so there is a gap around the filter/air box seal causing the noise. These places usually do this to help sell more filters. The Focus air box/filter is a bit tricky and I bet they didn't get it back in right. Easy to check.

 

[Jburks]

My guess is they pulled the air filter per their SOPs and didn't get in right so there is a gap around the filter/air box seal causing the noise. These places usually do this to help sell more filters. The Focus air box/filter is a bit tricky and I bet they didn't get it back in right. Easy to check.

this would be my guess too but i would also check the oil level. not saying it's related but i always get nervous after someone changes my oil.

 

[Tigeo]

^^^He commented that the oil level was fine.

 

[CRP16]

When I bought my 99 Miata last year on the test drive it sounded like the car had a CAI, I popped the hood and everything was stock all the way to the airbox. I opened the airbox and there was no filter. First thing I did was buy an air filter and now it is silent.

Perhaps they took your air filter out to clean it and forgot to put it back in, I'd check in the airbox just to be safe.

 

[NavyBurch]

So I went to check the air filter. The filter itself was seated properly but the guy hadn't screwed in the front right screw at all and the top half of the airbox was out of place. I am guessing he put the top half on incorrectly, couldn't get the screw back in, so he just left it open on that side. Maybe that was the problem?

Also, talking about filters, would the AEM Dryflow be a good replacement for the stock filter? What are the HP gains I should see? I know it will be minimal but anything is better than that stock filter.

 

[danbfree]

Yes, I have the AEM dry flow and its good, just make sure to do the snorkel delete along with it. Gives it a bit more growl and about eight HP compared to air intake systems that can run hundreds and get only a few more HP.