[Doggie 1]

136,681 kms in an '09 diesel and never a hint of a problem so something doesn't sound right.

[rcflyers]

At the end of June this year I bought a 2009 1.6 CRDi with 80,000 miles on it.

All was lovely until a couple of weeks ago when I suddenly noticed a diesel knocking noise too.

The mpg has taken a slight dip too.

It seems worse when cold or in the lower gears.

I guess I will need to get the injectors checked out?

[Phil №❶]

Diesel's always sound different at low revs due to the nature of their fuel ignition.

Unlike a petrol car, there is no flame front (or rapid burning) which originates from the spark plugs of petrol engines and travels through the fuel air mixture. In a Diesel, all the fuel ignites or detonates at the same instant due to the heating of the whole fuel air mix through compression. This happens at supersonic speed, which is the reason for the knock.

[cruiserfied]

If it's a rattle type noise at 1800rpm under light to medium load the reflash is probably the go.

[Hornet]

Believe everything said by Phil but
"This happens at supersonic speed, which is the reason for the knock"
The i30 is great but can they go that fast? 

[Phil №❶]

Petrol flame fronts that travel at supersonic speeds result in a detonation instead of rapid burning. Detonation in petrol engines destroys them, but NOT in Diesel engines, therefore the reaction is in fact supersonic. 

[Bitsumishi]

Hi everyone, been an avid reader of the forum for a while but only just registered! I have a 2010 1.6 CRDi 115PS CW with 5400 miles on the clock. I have owned the car from new. When I bought the car I was so impressed by how refined the diesel engine was - the most un-diesel like diesel I had ever driven! After 5400 miles though I have a bit of a problem that came on suddenly. The engine now has a harsher tone to it, especially around 1500 RPM and when I pull away under load in 2nd or 3rd gear from around 1200 RPM there is a loud knocking sound (like pinking in a petrol car only louder) until the engine gets to around 2000 RPM. It sounds like fuel detonation at the wrong time and seems worse when the engine is hot. Even my wife noticed the difference in sound when she drove the car and she is not very mechanically minded - she said it sounded much louder, like an old style diesel! The car runs ok besides this and the fuel economy hasn't changed. I have checked the oil and water and they are fine. I have got the car booked in with Hyundai next week but I was interested to see if anyone else had seen this problem so I could be armed with more information when the car goes in! Thanks in advance to anyone who takes the time to reply!

I know this is quite an old thread, but just want to add I had the same problem magically appear in the last few weeks on my 1.6 CRDi Diesel Engine.
Took it into the dealer accompanied by a printout of posts from THIS thread showing solutions. They told me it needed the ECU update that was required on "one or two" i30s they had seen. Funny how when I collected the car the girl giving me my keys back asked the service guy what they had done under warranty, and his immediate reply was "the i30 ECU update" and she appeared to know exactly what he meant. Interesting...
The service guy told me the injectors were - at a certain load and rev range - squirting fuel at the incorrect time. I suppose the effect was like 'pre-ignition' in a petrol car. Regardless, my i30 is back to its usual noisy little self and grumbling along nicely.

[Phil №❶]

 

  for the update

[Asterix]

Well, I remember the old type diesel injectors. If the spring inside the injector was getting weak the injector would open too early and the too-early-injected diesel would create a sound like a little guy was inside the engine with a hammer.

It would sound like the engine was about to fall apart... 

[Hornet]

Bitsumishi said
"They told me it needed the ECU update that was required on "one or two" i30s they had seen"

As a matter of interest does anyone know if these EMU updates (and others) are  made available by Hyundai to independent mechanics or must we forever return to the Hyundai dealers for EMU programming and resetting.
I do not like being tied to Hyundai after the warranty period.

[Phil №❶]

AFAIK, not obligated in Oz, but in EU apparently, they are.

[Hornet]

Sounds to me like a fuel problem. I had trouble when my CRDI was at about 5000k, poor performance and rough noisy running at low revs. A bottle of Hyundai injector cleaner, a tank of quality fuel followed by a highway 200k trip fixed everything. Hy then changed the fuel filter just to be sure.
I now have over 60,000k and everything fine
Good luch

[Azariel]

I have the same issue... Had my injectors replaced, then ECU reflashed and it was gone for 2 thousand kms... Now it's back :-( service told me that it's computer that rejects software after / during adaptation and it needs to be replaced however my electronic checked it and it seems to be OK... Any ideas and hindsight?

[jbh500]

Hi, sorry can't really add anything to my earlier posts - the car has performed perfectly ever since the injectors were replaced. Now at around 28,000 miles and running great!

[Azariel]

Good for you - thanks for posting anyway!