W124 E200 not running cold

[CLK320Cabrio]

Hi guys,
I am having a little problem with my motor, It starts ok hot or cold and is running spot on but from cold on first start it will not run unless i hold it on the throttle for 2-3 minutes, if then I ease off the throttle it will tick over fine and be ok the rest of the time untill engine has gone cold again.

I have changed everything in the engine bay, all temp sensors, air sensor,lambda sensor, repaired the main wiring loom and the coil wiring loom, new HT leads and plugs, no air leaks that I can find, so apart from a fuel issue, I doubt it's that becuse the car runs perfect apart from not ticking over when first started i don't know what to check next.

Anybody have any ideas as to what to look at next.

Thanks, Colin.

 

[bolide]

What error codes do you get?

Nick Froome

 

[CLK320Cabrio]

What error codes do you get?

Nick Froome

Hi Nick,
I don't know, I have the battery on charge tonight so I will have a check tomorrow and post back.

 

[GP801]

Throttle body? I only mention this because we had the same issue with a 1997 Polo 1.4 16v. Needed a new throttle body and the problem was cured. Only a suggestion as Im not even sure the systems are in any way similar.

 

[CLK320Cabrio]

Right Nick,
I have been out today and read the codes,
Pin 6= 1 no fault,
Pin 7= 33, somat to with A/Con, fault won’t clear,
Pin 8= 2…3…8, cleared all the faults I could and went for a drive then re-read the codes,
Pin 8= 2…8 came back, error 3 never returned.

So looking at the fault chart error 2 is a coolant temp sensor open circuit,
Took out the new one I put in last year to check the resistances and got these readings,

OLD 5.5 ohms at cold,
0.37 ohms in boiling water ,

NEW 6.00 ohms at cold
0.43 ohms in boiling water,

So I have put the old one back in , cleared the codes amd went for a drive again, and the errors 2…8 came back, which looks like both sensors are out of spec, what is the correct reading it should be at.

Error code 8 is apparently, idle speed contact closed signal incorrect, does this mean faulty or is it a result of the temp sensor fault throwing this up with it, can this switch be checked and if how, if not I have two options I can try,

1, spare throttle body but has the wrong plug socket which means I would have to cut mine from the car off and fit it to the spare to try it which I only want to do as a last resort really.

2, Cut the idle speed contact off the spare and fit that to the one on my car, number 2 seems to be an easier solution I think.

Any advice,
Thanks, Colin.

PS, I have checked all the throttle linkage and its operation and reset it to spec with the bowden cable, specifically contact with the idle switch, it definatly contacts the switch now in the closed position, I can just hear it clicking but don't know if it is working or not.

 

[bolide]

Idle speed contact closed signal incorrect is a Throttle Body fault. The late 6-cylinder cars use the TB to set idle. I assume your car is the same

The temp sensor fault could be a wiring fault, not the sensor

Nick Froome

 

[CLK320Cabrio]

OK, i'll check the sensor wiring but i,m sure that is alright because it has been renewed 12 months ago.

I have been looking at my codes again but I am confused, the booklet I am looking at is the Analogue systems 1988-1997, Digital system 1993-2000.

Page 11 tells you what the pins check for on the 16 pin diagnostic,
My pins are 1 ground,6,7,8,10, 16 power ignition on.
Pin 7 says its for A/C on W124

But blink code 33 on pin 7, on page 25 says it is Injection valve cylinder 1/4 short to positive.
I don't have an issue as regards the running of the engine, no feelings as if it is running on 3 with an injector not working, that's what is confusing me.

AM I looking at the right fault codes?

 

[CLK320Cabrio]

I have been out all day checking the integrity of all the wiring and earths and everything is now fine, had the crankshaft position sensor out and cleaned it, that is working ok, I then went for a drive after clearing the codes I had recorded, and the only one that comes back is the temperature sensor incorrect fault, the idle stop fault has gone away so I'm assuming the car has re-learned the idle position, and that there is nothing wrong with the throttle body itself because the car is now running perfectly.

I can only assume that the temperature sender I have is somehow not the right one for the car and giving below par readings to the PMS and creating the fault condition, it's not affecting the way the car is running.
I will have to get an Original Mercedes temp sensor unit and see if that removes the fault code.