Date registered: Feb 2010
Vehicle: 1986 420 SEL MERCEDES-BENZ
Location: Greensboro, NC
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Idling and Stalling on 420 SEL
Just bought a used 1986 420 SEL. When I bought the car, there was very noticeable stalling when I tried to accelerate during test driving. The dealer said the car had been sitting for at least 10 months.... so it may need a few cycles of high octane gas to clean the fuel system. So I added a full tank of 93 octane gas and drove the car about 120 miles back to my home. During the drive back, there was definite improvement with acceleration on the highway drive over the test drive. However, during the highway drive back home, on several occassions, the car would not respond as I had my foot on the gas pedal. It seemed like something turned off temporarily, then within 5-10 seconds the car would respond to my foot on the accelerator and drive like nothing was wrong. The car has been great on gas! after the 120 mile drive back home, I was able to drive for 5 more days after the initial fill up.
Now, during day-to-day driving, the car stalls occassionally and sometimes the engine completely shuts off. I would have to put the gear in neutral (while coasting), restart the ignition (engine starts up right away), and quickly put the gear back in drive. Sometimes this same event occurs when I am stopped at a light too. I was told by a Mercedes dealership to put a bottle of fuel injection/system cleaner in the tank and fill with high octane gas. In the last 2 days, the stalling issue has improved, but it does still exist. The engine still shuts off occasionally (where I have to put the gear in neutral and recycle the ignition), but engine starts right back up.
So I'm wondering is there any known reason why the car has this issue?? How long should I expect this to happen?? Confused, but ready to troubleshoot. I bought the workshop Manual, but I don't see a reference to this issue.
thanks for any help in advance,