Greetings,
Someone in this forum had said "Welcome to Mercedes, fix one thing, another breaks", boy he was right........

As you all know I had huge problems with my idle control system and finally the idle control unit fixed all of them, then the car started to overheat so I am pulling the radiator and taking getting it fixed.

Now I took the car to the mecahnic to do the fuel/air ratio adjustment as I messed with it while I was diagnosing the idle problem and he said the ratio was stuck at 50%.... Meaning that o2 sensor or Engine Control Module or Frequency valve wasn't working. And told me to check it...... My stupid $120 manual gives no information about how to check any of those things, but it does tell you what they do and where they are at (except I can't figure out where the engine control unit is at).

please help again

The engine control unit I assume you mean the computer or Electrinic Control Unit ECU as it is often refered to is under a plastic cover, which is under the forward portion of the pasenger side carpet.

And I disagree, when these cares are fixed right they are bullet proof.

Good Luck
John Roncallo

Do you have any testing instructions?

If I ever get it fixed I'll let you know.

...or they coould be referring to the Ignition Control Unit which is bolted behind the driver headlight on the wheel well. These are routinely available on eBay for a decent price. As with any used electronic part there is risk in buying one off eBay, but I've had pretty good luck with the spare parts I've purchased.

__________________
Don
'85 500SL (Euro) - 186,000 w/a complete restoration and engine rebuild at 154,000
'95 C280 - 174,000

No, I was talking about the ecu.

Try this link

http://www.landiss.com/mixture.htm