Quote:
Originally Posted by Aquaticedge
it dosnt... only thing i can think of that is cause for high idle is a Electronic failure or sticky linkages.
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First of all, bypassing the thermo fuel heater is generally OK unless in a really cold climate or you plan on being there someday. Out here we don't get freezing on the coast so I bypassed mine, even a new one started leaking a few years after I replaced it - more than a nuisance if coolant gets into the fuel!
I haven't seen sticky linkages on the 190D but on the 603 engine they do tend to break because MB went to plastic ends. Solution in that case is use metal 617 ends (still available relatively cheap or wrecking yard freebies).
I am assuming the 190D is similar to the 300D on the following:
First thing I'd check on the 603 when the idle is unstable is the connection where the pugs fits the control module. Moisture in the pins on the ECU (electronic control unit) will definitely cause the ELR feedback to act unreliably.
Remove the plug (lift it from one end) and if you see any moisture in there blow it out then use a hair dryer on the pins and reconnect it. A thin smear of silicone grease into the area around the outside edges of the connector will help keep moisture out.
Also unplug and replug the idle speed selector knob by raising then lowering it, not turning it to a new position. This will wipe the contacts in case they are dirty or wet and has been known to fix an idling problem.
The ELR is a sensitive system that works fine most of the time but a little crud can make it unstable.
DDH