On a 2000 CLK O2 sensor, which wires are the "heater wires", and which are the "signal wires".
Anybody have a diagram?

B

 

white ones (on sensor) are heaters. brown/black and black/red (ground) on wiring.

i think you can figure out the other two.

 

The check engine light is stuck on. I'm getting two codes:

P0170-fuel trim malf. (bank1)

P0173-fuel trim malf. (bank2)

Any clues?

B

 

it is definetly related to the fuel mixture, your first step would be to check the fuel pressure, it should be 3.7 - 4.2 bar (54 - 61 psi) and residual pressure after 30mins has to be at LEAST 2.5 bar (36 psi). if those are within specs then you should check the fuel delivery. the fuel pump should flow 1 litre in 35 seconds or under.

 

88Silver560sl,

Running fuel pressure: 52 lbs at idle and at 4000 rpm. Very consistent.

Residual pressure: 52 at shut off, then dropped to 33 lbs. after 30 minutes.

Fuel pump flow: Where is the fuel hose disconnect for testing this? Where do I take this measurement from?

Blue

Ps. Thank you for helping me.

 

I found the fuel/manifold/connection near the firewall, did the test from that hose.

Fuel pump flow: 1.8 Litres in 35 secs...

Blue

 

hrrm, this is where it gets tricky. the residual pressure is a little low, so you may want to check to see if you have a leaky injector. all in all this test is pretty safe but be sure to A: Have a fire extinguisher handy just in case, im sure you wont need it, B:have someone qualified to do this if for ANY reason you feel uncomfortable (i have done this hundreds of times and never had a problem) and C:NO sparks, flames, smoking, or any source of flames gasoline is very unpredictable and i almost had it get away from me once not a pretty thing(was taking a connection off of a fuel pressure regulator with some pliers, pliers slipped off the clamp and sparked setting the fuel ablaze. another good reason to keep a fire extinguisher handy because things can happen out of your control) OK, so here we go.

1) run the engine for a few minutes to get the juices flowing in the fuel system. (doesn't have to be operating temp.)

2) make sure the engine is off

3) unbolt the fuel rail and carefully pull it out(make sure not to disturb the connections at the top of the injectors)

4) place a dry towel or container under all of the injectors

5) Turn the ignition to on, DO NOT START, just on.

6) check for leaks for about 5 minutes

7) if you find a leak, replace the leaking injector

8) bolt the fuel rail back in

if this doesnt fix the problem, then you may have a contamination problem. pump out about 16-20oz of fuel and put it in a CLEAN CLEAR glass, check to see if it seperates. if it has water in the fuel, then you will see a slight color difference at the bottom of the glass (water is heavier than gas). if this also proves unsucessful get a blank white piece of paper and put a drop of gas from your tank on it. if it leaves a stain on it when it evaporates, its contaminated.

 

88Silver560sl,

For some reason this morning, I have NO fuel pressure

Could I have tripped a fuel shut off switch when I disconnected the fuel line and pumped fuel out?

Blue

 

Injectors: I'll check my injectors just as soon as I get fuel pressure back.


Fuel pressure: I'm trying to figure out what happened to my fuel pressure.
So I connected the fuel pump wires directly to a 12 volt source, with aligator clips, to by bass all electrical controls, and you can hear the pump run, but still NO pressure at the manifold.

I'm testing pump, filter, regulator now.

And by the way, I really appreciate your help on this 88silver560.

Blue

 

OK ran low on gas.

I tested the fuel pressure directly at the pump, and it pumps 100 lbs easy.
The fuel filter is ...ok.

OK on to the injector leak test...

Blue