Had poor idle on my 1988 300 E with 100,700 mi. Took it to shop for $1,400 repairs. While 60% better, still idles rough in neutral. The work they did:

New plugs, rotor, distributor cap, replaced intake manifold gasket, replaced all hoses for idle air system, replaced air sensor plate belows, replaced fuel injectors and seals, performed engine decarb.

Most of the improvement came with the new plugs and dist. cap and rotor. Is it unreasonable to expect the car to idle smoothly?
Any recommendations?

Also, anything that can be done to improve ignition static and reception on stock MB radio?

Thanks,
Bill

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Bill W

On the radio, I would check that the antenna has good contact with the body where it mounts.

The car should idle well, espcially with all the work you had done.

The remaining suspects are the mixture, the fuel distributor, the EHA , the O2 sensor, and the lambda control in closed loop.

There are a lot of posts on this subject and a really good one is "My last EHA question" by Cap'n Courageous.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Did the radio static begin after this recent work? If so, I'd ask about the type of spark plug(s) used. Some types of plugs are known to cause this problem.

Check out this URL and look further down into it for Radio Frequency Interference:

http://www.centuryperformance.com/spark.htm

Ignition static is almost always lack of proper resistance in the ignition wiring and plugs -- one reason to stick with OEM plug wires.

Engine vibration at idle after a good tune up is almost certainly out of range idle mixture, a bad OVP relay, or a bad EHA. If it leaks, it's shot on the latter.

Also, check the engine mounts -- they are a spring mount, enclosed in rubber with a limited area annular orifice, and filled with glycol. When the rubber wears out and the glycol leaks out, the spring is free to allow the engine to vibrate, and it does, quite a bit!

You can tell by looking if they are shot -- there is a tapered steel insert on the bottom of the mount. If you cannot see this tapered portion because it has collapsed into the mount, it's shot. Ditto if you can see the oily glycol on the mount or frame.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter, good response on the engine vibration issue. My '92 300e has a vibration when in Park. The engine runs very smooth... no engine miss, but a vibration can be felt in the car. I suspect either bad exhaust hangers or motor mounts and now I know what to look for.

Thanks,
John