1989 300E Starting problem

May 07, 2004 3 Replies

I have a 300E w/217,000 miles. The only issue I have with the car is starting it. Unless it has sat over night, the car will not hold idle upon starting. I have to hold the idle @ 1000rpm for 10 seconds, then the idle settles down to a noce smooth 600-700rpm. Sometimes this goes away, but the problem has returned. Any Idea's?



Thanks, Thom


Cold start system isn't working. Temperature sensor, time relay and cold start (injector) valve, This is the chain; you need to find which is defective or unplugged.

He said it starts and runs okay when it has sat overnight. It's the rest of the time that he's having a problem. Doesn't sound like the cold start system to me, unless it's firing when it shouldn't.

I think we need more info., like does it run okay after it's warmed up regardless of starting conditions? What if it's running fine and you shut it down and start it again immediately--does it still go into a bad idle? When you say it won't "hold idle", does it stall? Hunt? What does it do exactly?

Bill Balmer

1986 190E 2.3-16

Once it is running, it never dies, nor does the idle drop below

600rpm. If I try to start it immediately after shutting it down, it takes about 4-6 seconds of cranking before it fires up, but it will still try to die if I let it. Once it is running, it never dies, nor does the idle drop below 600rpm.

I'm getting ready to give it a tune-up, hoping sme new plugs and other items might help. I got the car from my father, he told me he was running regular unleaded in it. I am running only Shell or Marathon premium in it (the manual says minimum 91 octane), plus I am trying to stay away from methanol/ethanol.

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