1975 Mercedes 450SEL ECU

I have a mint condition 1975 Mercedes 450SEL (body 116033-12-032662, engine 117983-12-032803) with only 95,000 original miles. It has had everything possible done under the hood, short of a new engine, and it continues to idle ruff and perform inconsistently. Engine facts: good compression, no vacuums leaks, all new injectors, all new engine sensors, new plugs and plug lines, new distributor cap, rotor, and points, new coil, all new vacuum lines, new fuel pump and filter, new EGR value and air-injection pump. Timing set to TDC and dwell at 31.5 degrees. The only thing left is the electronic fuel management computer, which seems to be functioning ok. Unfortunately, 1975 was a horrible year for cars because of the newly established emission standards. This is especially true for cars sold in California, USA. Mercedes didn't escape this problem and they created a real Frankenstein smog system for my car, which I presume included the electronic fuel management computer. My questions: (1) is there an after market computer management system that I can install on this car to help it operate better, or, (2) is there a carburetor/manifold replacement that I can use? Any suggestion would be most helpful.

Sounds like you have a great car! Has anyone removed the ignition distributor & replaced the "Trigger points" for the injection system or at least inspected them? The 1975 model was the last year for EFI & the system wasn't all that bad. The only bad thing was the catalytic converters on the exhaust manifolds!!! Keep the car original, have the system checked out by some old guy who was working on M.B.'S when your car was new!

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MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS M.B. TECH

I have seen trigger point problems and the fuel injection control unit faulty cause the problems you are experiencing. I would not use any aftermarket parts!!

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM