Rant - PeachParts Mercedes-Benz Forum

Since66 · #1 07-24-2009, 05:48 PM

Pulled up beside a nice black 2008/09 CLK 550 AMG convertible today. As it pulled away the distinct sound of detonation filled the air. I'm thinking to myself: "You twit! Lady, you've got a car there that prolly exceeds $100K and you can't afford to pay 20 cents more for premium gas?"

The tip-off should have been that the car needed a wash....badly.

People!!

[harrumph]

aklim · #2 07-24-2009, 05:59 PM

That is weird. The Knock Sensor should have retarded the timing. Must be something else wrong

Fulcrum525 · #3 07-24-2009, 06:03 PM

No such thing as a CLK500 AMG
CLK550 Sells for around $55,000
Remember some people just make it look like they can afford the car

Angel · #4 07-25-2009, 02:33 PM

I've always wondered about knock sensors and ECM's (ref the previous question)
They retard timing when they sense knock, ok, so when do they unretard timing ? after 3 stop-stop cycles ? after 30 seconds ? after the gas tank gets filled up again ? If all an ECM did was retard timing, after one tank of low-grade fuel, you'd lose power (retarded timing) and never get it back.
so....

I'm sure the car advances the timing every so often to see if there is still 87 octane rolling through, and when it "checks" like this, you'll hear the pinging sounds come and go away when it realizes 'yeah, we still got the cheap stuff'... makes sense to me.

-John

-John

Hatterasguy · #5 07-25-2009, 03:27 PM

Probably a lease.

No such thing as a CLK550 AMG, the 550 is about $70k, lease is probably $800ish a month.

aklim · #6 07-25-2009, 04:03 PM

Quote:

Originally Posted by Angel

I've always wondered about knock sensors and ECM's (ref the previous question)
They retard timing when they sense knock, ok, so when do they unretard timing ? after 3 stop-stop cycles ? after 30 seconds ? after the gas tank gets filled up again ? If all an ECM did was retard timing, after one tank of low-grade fuel, you'd lose power (retarded timing) and never get it back.
so....

I'm sure the car advances the timing every so often to see if there is still 87 octane rolling through, and when it "checks" like this, you'll hear the pinging sounds come and go away when it realizes 'yeah, we still got the cheap stuff'... makes sense to me.

-John

-John

Here is the thing. The KS will retard the timing before you hear it. It is more sensitive. That is why when you rev up, sometimes it takes a little timing off because it senses a sound within a certain frequency range. A sound that you would not hear. When you can hear pinging, it is way out of line. IIRC, In my 91 Vette, it would retard the timing 2 degrees at a time till the KS doesn't hear knock. Then it advances it 1 degree till it hears knock then backs off. If it were to do that, I doubt you can hear the knock.