Hey Guys,

Last month after help from this board, I replaced the Fuel System Relay on my wife's 420SEL which was stalling about once a day. It would restart fine, but I was worried it would stall in front of a big truck. The new Relay seemed to work for about a month, and today the 420 started stalling again, this time twice today so I'm worried again.

This time is kinda different too. It stalls as she is slowing down or hitting the brakes. The fuel gauge is at 3/4 tank, so theres lots of gas in the tank.

The 420 has 153,000 miles on it and other wise is in perfect condition.

Any suggestions would be a big help.

Thanks,

Rod

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1998 Land Rover Range Rover 66K Miles
1988 300SE Totaled in 1998, hit by drunk driver, but we walked away OK
1989 420SEL 140,000, just warming up. Total by 18 wheel gas truck rear ended, but refused to lose another MB. Had it repaired cost $10,000+ Great Car again SOLD it for a 2003 C320 to save on gas
1991 2500 Suburban 454, 130,000, Best truck in the world. SOLD it out right.
1952 8N Tractor 1,000,000-/+

A sticking Idle Control Valve caused a similar stalling problem with my 1987 300e.

If your 420 engine has the same K-Jetronic fuel injection system, that's the first place I'd look. Plenty of info here if you do a search.

If cleaning the ICV doesn't help, check it has good electrical connections. If the wiring seems OK, check the soldered connections in the engine management module. They deteriorate over time and a bad connection there can cause all sorts of on again/off again problems.

good luck

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1987 300e manual 250,000 km (sold)

I would like to add, that simply spraying a little "carb cleaner" won't do the trick. You need to really get in there, and clean the daylights out of it.

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

absolutely agree. you need to take the unit off, block up one tube, fill it with carb cleaner and leave it to sit overnight. you'll be amazed by how much black gunk comes off the internals.

here's some info on different shutter positions depending on voltage

http://www.peachparts.com/shopforum/showthread.php?t=96842&highlight=icv

when you take the unit off, check both hoses for cracking. leaks here can be a major cause of fluctuating idle and stalling woes.

if it's any help, I finally traced all my idle nightmares to bad connections at the ECU. Fortunate enough to be able to fix by resoldering the connections instead of buying a new one.

Of course, along the long and winding road to discovery I checked or replaced pretty much everything else: coil, plug wires, ICV, dist cap and rotor, airflow pot, OVPR, FPR, fuel accumulator, pressure regulator, filter, hoses, connectors, yada yada yada

i think this is some kind of MB initiation ritual

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1987 300e manual 250,000 km (sold)