SamuelP

Cold car starts. As it gets warm starts chuggin'. When it reaches 80C really gets bad and dies. Won't start back until cold again.Is there a sensor or something unplugged, or _________________? It has to be something simple one would think.

Any suggestions? I'm waiting on responses before proceeding. Thank you.

Help!

SamuelP

Possilbe the O2 sensor? Or MAF?

SamuelP

Replaced O2 sensor to no avail. Replaced temp sensor to computer and mostly a fix?

Fires up; runs good seemingly through 85C and then at ~100C starts missing again.

Still seems a little rich on fuel and this car idles at 600RPM? That idle seems low to me. What is it susposed to be?

Poundy

When running well should idle around 550 in drive and 650 in park. Might be worthwhile giving the Idle control valve a clean.

SamuelP

Would love to; where is it?

Update --- Since I replaced the temp sensor to the computer: it ran a little rough and next start, a little and then a little better with the next start?

If I didn't dream it; I read somewhere that it generally takes 3 times for the computer to sync and get back to normal. True or not; it smoothed out and now seems to run fine. I've done some road running and it now seems smooth.

But, it is going to 100C and seems that the 2 elec fans are not coming on? Circuit breaker or _________ and its location is where? I can't seem to find anything.

Poundy

The electric fans only work with the A/C on or when the engine exceeds 110c
they are 2 speed and will usually run on and off in cooler weather on low if at all. If the A/C is working very hard in hot conditions it may engage high speed on occasions or if engine temp tops 110 to cool it down. If you feel you are not getting adequate engine cooling it will most likely be the clutch in the viscous fan that needs replacing. When you get back from a run, turn off the ignition and turn the Viscous fan it should be hard to turn, if it is easy get the clutch checked out it most likely needs changing.

SamuelP

Thanks a ton Poundy; I appreciate your taking time to post your valuable information. Glad somebody know. Now: do they operate from the computer via a relay or a sensor? This may avoid me asking again?

Poundy

Just passing on info that's been given to me by some of the clever clogs at benzworld

For the engine temperature there is a coolant temp sensor on the top of the manifold ( attached to a largish black round connector with 4 pins) this is the one that tells the Aux Fans when the car is above 110. The smaller blue one on the right just goes to the dash gauge.

For the A/C the sensors are on the drier behind the LH headlamp, I believe it is the green one that can cause problems. If you take out the light unit I would imagine it would only take a few moments for a A/C tech to test them.

Obviously there may be other scenarios but these are the easy diy fixes to start with.

morganb

Samuel,

Do you have a The Part Number of what you replaced? I may have the same issue.

SamPickens

0085424517MY 1 Mercedes Coolant Temperature Sensor - Meyle 0085424517MY $20.15 $20.15

From: FCP. I've found that to be a valuable site. To get all on track: replace O2 sensor and CPS.

UPDATE: Normal temp for me now is ~83 to 90. Summer @100+mph and it don't excees 100C.

This forum is great and its people are kind and good to help. Sam