Skip the auto shop - Our mechanics make house calls

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?

A: Hello. There could be a problem with the co...

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?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: When accelerating from standing stop engine hesitates

I would recommend checking the mass air flow sensor as this is a commonly known part that can cause this kind of loss of power. This regulates the air intake into the fuel injection and ensures a proper air/fuel mixture....

Q: Electrical issues, power steering shuts off & car stalls.

It is most likely a coincidence that these problems began happening after the turbo was replaced. However, it is possible something that occurred during the diagnosis or repair of the turbo may have created all these problems. Regardless, with the...

Q: How do I view the range in the multi-information display?

The range setting shows you approximately how many miles you can travel on your current tank of gas. The distance is estimated based on the fuel remaining in your fuel tank, as well as your average fuel economy. To view...

Related articles

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...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.