PeachParts Mercedes-Benz Forum - View Single Post

mctwin2kman · #33 10-07-2004, 11:05 AM

If you have the car with you and a Volt Ohm Meter you can check the sensor yourself.

The Chart of temps follows!

-20 15.7KOhm
-10 9.2KOhm
0 5.9KOhm
10 3.7KOhm
20 2.5KOhm
30 1.7KOhm
40 1.18KOhm
50 840Ohm
60 600Ohm
70 435Ohm
80 325Ohm
90 247Ohm

Now mine was reading lower resistances than it should of at said temps, causing the engine to be too lean at cold start and the Cold Start Injector to not fire. So I would have to try starting the engine twice basically and sometimes pump the gas to get it to run and warm up engough to stay running. Also had some issues with a warm start when shut off and then started less than an hour later. The temp sensor would read higher thus causing too lean a mixture. Also had ****ty gas mileage until fixed. I have also broken 2 of these sensor due to slip of the wrench type activities under the hood. Right now one post is broke off and a wire soldered to it to keep it connected, so I need to replace mine again as well. It is a fairly easy test. You just take the leads off and test the sensor. Then warm the car up to 80 degrees and turn off and test again. If your mixture is right you should be able to do this while the engine is running but may get a little bit of a stumble when you unplug it. If that is ok then I would say maybe the EHA is bad! But a 5-10 minute test of this sensor answers a lot of questions. Also have you tested your Cold Start Injector to make sure it works! Another easy one, you just remove it and put 12 V accross the connector momentarily and see if it clicks and fire. You can even re-attach the fuel line and check its spray pattern this way. Just don't light a match while doing it. And on a side note, if you are mechanically inclined, you should get the MB Maint CD as they are very helpfull in trouble shooting and testing everything. It has saved me from taking it to any shop. I have done all the work myself using info from this forum and 190Rev and that CD. Save a ton on labor costs and order all my parts online and save a ton there as well. I was quoted at $730 in labor to do my heater core from an MB Indy guy. Did it myself for free and an afternoon off. Took 5.5 hours and now I have heat again. So I saved myself $730 just because I am a cheap bastard. Good Luck and hopefully you get this resolved soon.