[bbuyuk]

Hi all.

I have a 2001 model SLK 320 (36.000km).

Today when I start the engine, it seemed like some of the cyclinders are not working and the car was not going good and shaking (like the engine is going to stop).

The petrol was nearly the end (I mean the low petrol light was on, but still there some in the tank). So I have thought that it could be some dirt at the end of the tank and this could be the problem.

Then, the "Engine Diagnostic Indicator" lamp was on. I have filled the tank (full). And it was still in the same condition (shaking and could not go well). Then I came home, and shut the engine off. And turn it on again. It was fine... But that "Engine Diagnostic Indicator" lamp is still on. And I left the car in the park, and began to write here...

In the manuel, it says "there may be a malfunction in the fuel injection system, the ignition system or in the emission control system. The emission limit values may have been exceeded".

Has anyone had such a problem before? Can it be the dirty petrol (unleaded 98 octan I use) and will be OK soon? Or do I have to take the car to the service immediately?

 

[page62]

Replace your fuel filter. Put some Techron in the tank. Let us know what happens.

For the rest of you, take this as a lesson: DO NOT LET YOUR PETROL RUN TOO LOW!!!

 

[TheJimbo]

Technically, it shouldn't matter how low the fuel goes. The fuel is pulled from the very bottom of the tank. If it was pulled from any higher, then you'd always have that last bit in there never to be used. The fuel filter is there for a purpose.

The only time there would be an exception to this is with a manual reserve switch as is found on motorcycles. You run on the top part of the fuel switch normally, then when you switch to the reserve position, you run on the lowest part of the switch. So if you run on the top part for a very long time, then switch over to reserve, you'd run into a potential sediment issue.

 

[page62]

In theory, you are correct.

But I learned an interesting lesson when I replaced the fuel sending unit in my 450SL. I was able to look into the fuel tank with a flashlight. It was easy to see there were all sorts of cruddy bits floating near the bottom of the tank. As the tank nears empty, these bits get sucked towards the fuel intake screen (don't know if the R170 has this).

In fact, when my 450SL gets below 1/4 tank, it's been known to stall...for this very reason.

So I speak from experience and not conjecture on this point. (I usually try to do it this way...but I ain't perfect! )

 

[TheJimbo]

I hear ya. Technically though, it's an urban legend (old wives' tale) that letting your fuel run too low brings in sediment (unless it was floating on the top of the gas). The fuel gets pulled from the very bottom whether you have a full tank or an empty tank (other than the mechanical reserve switches as mentioned). In any event, the fuel filter is there to catch that kind of crap before it makes it's way into your engine potentially causing hesitation. Some fuel injection systems have two filters - one back by the fuel pump and one in the engine bay just before the injectors.

The issue you experience could easily be air being sucked into the line due to the low level of fuel in your tank sloshing around when you hit bumps or other uneven road surfaces (hills too). I had a truck that I could let go way down - until I hit a hill, then it would bog and chug until it died.

I had pulled a fuel tank off of an old Honda once. Like your expereince, it had plenty of crap down on the bottom (VERY old car!). None of it got past the filter, though.

 

[Kirill]

go to autozone - have them read to CEL code - that should help in diagnostics