Q: Rough idling and lacking horse power - 1982 Mercedes Benz 380SL

asked by on

I have a 380SL that sat around for 9 months and has some engine problems. The odometer is broken, so I don’t know the mileage on it. I have quite a few vacuum leaks. I put in all new fuel injectors, gaskets, hoses, spark plugs, leads and a distributor cap. I checked the distributor and a many of the valves. Everything seems to be working OK. My friend helped me hook up the pressure gauges and set the fuel pressure of the warm up regulator and set the timing. It passed the smog check in California. So my car runs the way it’s supposed to when I start it from a cold start. It gets good idle rpms, fuel economy, horsepower, temperature, etc. It’s perfect! But when I start the car after the engine has been warmed up or hot it idles rough with a wave of rpms, awful fuel economy, hardly any horsepower and almost does a complete stall. It does this consistently. I was thinking it might be the ignition control unit, temperature sensor, over voltage relay, O2 sensor or something else. Do you have any ideas on what might be wrong?

Hello. There could be a problem with the coolant temperature sensor. I would also suspect that there could be a problem with the ignition control unit. The fuel pump could also be contributing to the problem you are experiencing. If the fuel pump is weak or not getting the proper voltage, this may cause a problem like the one you describe. Have a certified technician, like one from YourMechanic, diagnose the rough idling in order to make necessary repairs.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Rough idling and lacking horse power - 1982 Mercedes Benz 380SL

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Mercedes 380SL starting up, rough idling, then cutting off and dying

The mileage is not that high but due to the age, before attempting further diagnostics, you should test cylinder compression and intake vacuum (to check for stuck valves). If you determine that the engine is basically mechanically sound, there are...

Q: Q: Stalling at stop lights

Hello there, a few different faults could be causing your 2000 Plymouth Breeze to stall. The most common would be the fuel pump, MAP sensor, fuel filter, battery, alternator, battery cable, or a wiring fault. To have all these items...

Q: Possible fuel injector problem that I need fixed.

Clogged fuel injectors are a possible cause of this condition along with a clogged fuel filter and weak or inoperative fuel pump. My first suggestion would be to have a professional do an inspection. If fuel pressure is low then...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...