Help me diagnose a noise.

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Diagro

Diagro

Diagro

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3 Jun 2012
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Hi

There is a noise that's driving me mental, i cant find where its coming from, nor can 2 garages.

Since i have the DPF Gutted and a remap a noise had started to creep in, at the start it was not there, then a week later it started but minor and now its there all the time when accelerating. Also i should add, this noise isn't making an appearance when revving at a standstill.

When i accelerate a noise i can best describe as "Grinding" makes its self known. Two garages say its more of a rasp, coming from the back so must be the exhaust.

I had a custom exhaust made for the car and fitted to try and remove the noise, makes a nice sound when revving, but this bloody noise pops up and is now worse after the new exhaust... Possible that the removal of a silencer has made it louder? Seems like a waste of money this new exhaust.. then again its Stainless Steel so i don't mind.

The only thing i can think is that its the DPF making the noise when lots of exhaust gas passes through it, causing something to resonate or vibrate making this noise... left over filter material?

What would you think it could be? I cant get a video as it doesn't seem to show up on a video, but it is loud enough to overpower the engine noise and can be heard with the radio on. Not to mention it sounds horrible from outside the car.

What do i do? :(

Edit:
Its a Mazda 3 2.2d 185, Has been mapped to 210PS/475NM
 
After some research it looks like an engine mount or exhaust join issue. When engine tilts under loaf the exhust joins may give and produce a gap hence the noise.

It's booked in with the tuner who did the dpf and map now, they can't see it till next Saturday thoughso iI have to live with the mental exhaust grind till then.
 
Try replacing the gutted DPF with a new one so that you're no longer illegally spewing out lethal amounts of NOx and particulates. It might fix the issue, or at least one of the issues. ;)

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pepsilol said:
Whats the reason for actually gutting a DPF?
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It was regenerating every 200 odd miles. Costing a fortune in fuel doing so. Turns out it's been cleaned by a third party at least twice based on the chemical stains found on the filter medium.
so was basically screwed.
Mazda wants 1700 for new dpf fitted... yea no.

with the thing gutted you get better exhaust floe, much like removing a high cell cat. Better mpg too.
 
You fitted a stainless exhaust to a diesel so it makes 'a nice sound when revving'? Oh dear.

With it regenerating every 200 miles, is it because it was actually faulty, or because you just do a lot of town driving?
 
I can't get over the logic here - if it was regenerating so often that it was having such an effect on the mpg, it's clearly faulty and should have been returned to the garage you only recently bought it from. Instead you've removed any hope of having it properly fixed and possibly created more issues. Reflect the sentiment about the exhaust and how stupid it is trying to make a diesel sound good, the best thing you can do to make a diesel sound good is try and shut it up. A grinding noise on acceleration could be a failing turbo
 
Im not discussing the DPF here, I dont care about that.

Went to a garage today. They diagnosed it as potentially an Inter cooler / Waste gate issue.
They said it sounds like the Waste gate is opening up just as the turbo is around 50% boosting. and then just exhausts the air with a horrible air/exhaust/raspy noise.

This is something thats 100% covered under the Carselect warranty so meh its being fixed monday
 
Sounds like your Remap is working well then..

I look forward to the next instalment of your Racecar Mazda 2 diesel hatchback story.
 
iaind said:
I suspect they'll notice the exhaust!
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Who? The Warranty company?
Exhausts are in their exclusions list anyway so why would they care?

Also unless its a major job they wont even come look at the car. Simply just send me the payment to cover the bill.
 
The amount of times I've heard stories of remapped diesel engines going bang....

I wouldn't risk it myself. At least not without physical upgrades as well.
 
Next you'll be telling us you've modded it even more so it sounds like it's sneezing when you change gear.

Seems to go hand in hand with custom exhausts on diesels lately.
 
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