stickygreen

Being the first year for the '09 BTC, I imagined we would run into a few glitches, but I didn't expect it so soon. At around 2200 miles, the CEL came on - dealer diagnosed it as a faulty knock sensor. This was last Friday and for some reason the part is on back order...should hopefully show up sometime next week.

On the plus side, everything else works flawlessly and we are averaging around 24 mpg. I just hope this is a freak occurrence and not an indication of things to come.

Blk04cobra1

Im sure it's just a freak occurence. Those sensors can go bad at any time unfortunately. Nice avg MPG's though, wish I got that in my Tahoe.

lkchris

You can call it first year if you want, but the engine's the same as those in 2007 and 2008 GLs. The difference is the stuff on the exhaust system and perhaps a bit different tuning to compensate.

Brocktoon

Knock sensor, on a Diesel?

Funniest thing I ever heard. Service department has to come up with better excuses than that.

BTML

I test drove a 09 BlueTEC ML last week and fell in love...
I am seriously considering a trade in the coming weeks.

stickygreen: Apart from the 1 hick-up, how would you rate the overall performance?

RedG

There is a lot more than just a different tune, and exhaust.

Why? What does it benefit them to lie to him? And why do you think it awkward to have a knock sensor on a diesel engine? Do you know the inner workings of Bluetec on Mercedes cars? I'd doubt it.

Brocktoon

You slay me! What is the knock sensor 'posed to do? Adjust the spark timing?

Second, a Diesel engine operates on the mechanism that causes "knock" on a petrol engine.

Third, you have no idea who you are talking to, so please keep your doubts to yourself.

RedG

Are you a Mercedes Benz engineer? Did you design BlueTec or Biodiesel engines?

Brocktoon

oooh, more recon for your flame war? I'm not biting.

RedG

Oh yea, recon for my flame war...ok.

I really don't care if you argue the point or not, the fact still stands even the porter at a MB dealership has more informational knowledge of MB Bluetec than you do. My question still stands also, are you a MB engineer, or did you design BlueTec engines?

am_beagle

I think the question should be "Is there a knock censor on a diesel engine ?"
The guy is a MB engineer or not, is HIS business, We are here to learn and to share, my friend. Thanks.

stickygreen

Knock sensor is what I was told...will find out for sure once the part comes in.

Performance is great once on the highway, but a bit slow to get going around town. I also feel that the transmission gear ratios are too closely spaced, but overall it is an excellent drivetrain. The 320 engine is much better suited to an ML, but works fine with the GL. If only there were a GL420...

We haven't had any other problems, and the new navigation interface with voice control is fantastic. The runflat tires are great for safety reasons (don't want mom stuck on side of road waiting for AAA), but they do ride harder, make more noise, and are pricey.

My aunt has an '08 ML550 with P3, and the air suspension/ADS is worth every penny. The ADS on our GL320 is what makes the runflats tolerable...

stickygreen

I was referring to all new stuff for '09, such as Bluetec/emissions equipment & sensors, new COMAND interface, etc.

Ausmbtech

Actually there have been knock sensors on MB diesel engines for a number of years now. They're there to fine tune the start of injection/injection shutoff. They are there to hear the normal knocking of combustion and recognise it as the start of combustion rather than a sign that the timing needs to be pulled back like in a petrol engine.

I understand the confusion. Same technology used for a completely different purpose.

lkchris

List it.

oknish

I concur. Share the knowledge.

oknish

I couldn't agree more.

Brocktoon

I am not an MB engineer, nor am I a porter at a dealership. I am however a VP at an oil and gas and natural gas transportation company. One product I am directly responsible for is the provision of natural gas transport solutions (CNG, LNG and a proprietary mode) and conversions of petrol and diesel fleets from automotive to OTR transport in scale. As one poster had noted, off-the shelf "knock sensors" are sometimes used in diesel engines, however they are tuned to be listening to other sounds of combustion, a diesel engine that is running is always knocking, and as such are really not knock sensors.

But hey WTF do I know?

stickygreen

Got the Bluetec back yesterday...work order said "replace front knock sensor"

flu200

The Check Engine Light went on for my 09 ML320 BT too! But it turned itself off today after 4-5 days of occasional driving. The dealer asked me not to be worried even when it was still on...guess it must be a common glitch.

Maybe it is also the knock sensor - I guess I will ask them to check it when the 1st service comes up.

BTW. the engine oil is really dark after 5K miles. I am thinking to change it before it get to the 10K miles (1st service). I never believed you can run a engine for 1st 10K miles - after all...those metal stuff need to rub against each other to break in....

Fourdiesel

If you have never owned / driven a diesel before, the black engine oil is completely normal and is to be expected. After each oil change, the engine oil turns black almost immediately! DO NOT change the factory oil fill early. It contains a special additive package that is DESIGNED to coat / protect all surfaces that need such protection. It needs the FULL service interval for the chemical reactions to take place that do this. If you change this oil early, you defeat these protections! The color of the oil is NOT the determinant of the need for an oil change!The Bluetec engine is no different in this respect.

flu200

Wow...I am a newbie in diesel cars...many thanks for the information. I will wait to the 10K mile then.

zoink

Hold on... so you're saying that we HAVE TO follow the FSS and shouldn't do oil change in between?

I usually do an oil change every 6 months regardless the miles elapsed since last oil change, except when the FSS says next service is almost due.

lkchris

No, you shouldn't.

ALL of this information from a VW forum applies (UOA means used oil analysis)
http://forums.tdiclub.com/showpost.p...8&postcount=15

Fourdiesel

You don't HAVE to do anything - change oil every 10 days if you want to. It is YOUR vehicle ... What I AM saying is that the engineers and designers at Mercedes -- who know a great deal more than I do about such things -- have specified a special break in additive package for these engines that is DESIGNED to be in the engine for between 10,000 and 19,000 miles in order to do the best job possible to protect the engine and to make it possible for the engine to last the 500,000+ miles that Mercedes diesels are known for. The design features of these engines are very carefully thought out and integrated in a way that very few other companies can. They are justifiably proud of their reputation in a way that few US companies can understand. I believe they intend to keep that reputation.