I believe that the warm up regulator on my 83 280SL (Euro) is faulty. The symptoms are a stumble on acceleration when the engine is cold. It starts and idles fine hot or cold and runs fine when warmed up. The plugs, wires, cap, and rotor are new, and the valves have been adjusted. The car has 76,000 miles on it.

Three questions. First, how can I tell for sure that the warm up regulator is faulty?

Second, can this device be adjusted, cleaned, or repaired, or is it just replaced when faulty? The service manual tells how the unit functions but doesn't tell how to test it or replace it.

Third, is this a DIY job, or should I take it to a local shop? We don't have a MB dealer or MB specialist in town, but there are some shops that specialize in import cars, including one that is an authorized VW/Audi shop. I assume that someone familiar with Bosch fuel injection systems wouldn't find this too much of a challenge.

Thanks for any input you can provide.

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If it starts fine when cold but just won't accel properly, I would think that you have a vacuum line to the warm up regulator off. To test requires the use of a special fuel pressure gauge set up.

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