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Discussion Starter #1
To start off, I have a 1988 300E with 169,000 miles on it.

Basically, my car has a pretty rough idling problem... It bounces back and forth between 650 and 800 RPM while in neutral/park, and whenever it hits its low point it shakes the entire car. It has reasonably new plug wires (changed 25,000 miles ago), the plugs have been replaced, I've run fuel injector cleaner through it every oil change, but it still is plagued with the same problem. It's been in the shop, but they couldn't figure it out. Anyone have any suggestions? This has been going on for the past 45,000 miles with no change whatsoever (since I got it basically).

Also, every 300E I've ever seen makes a hissing sound while running. I know it's normal, but what exactly is it? It used to be pretty constant, but now its pitch oscillates just like the engine speed does at idle. If I can find out what creates that noise, I might be one step closer to diagnosing the problem. Any advice would be appreciated.

One last question is how difficult would it be to swap a 5 or 6 speed into the car? I hate autotragics, and this car is on its second one since I've gotten it (and I have to manually caress it to downshift into 3rd on the highway or it'll just drop into 3rd instantly and jolt the entire car... It feels like it's ripping the drivetrain apart. The replacement is from an '86). Would I have to find an OE 5-speed from someone in Europe? Or would another manufacturer's transmission, such as ZF or Getrag, bolt to the factory I6? I'm going to keep this car as long as possible, and it'd be nice to have a little more fun with it, not to mention the added benefit of better fuel economy. Thanks in advance!
 

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Discussion Starter #3
Well, if it's a vacuum leak, I know exactly what the culprit is. The vacuum lock assembly for the fuel door was cracked when I was rear-ended a few years back, and rather than tracking down a replacement part (when I was told it was a $500 part, when in all reality I found out today it's $20), they just plugged up the hole that went to the trunk locking mechanism. I'm heading to the dealership right now, so I should be able to get that squared away. It works for the most part, but every once in a while I hear this weird moaning sound that started once they did that, so apparently the plug isn't working too well.
 

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I have the exact same problem on my 88CE, its hard to start when warm and shakes when in D and idling to the point that its noticably embarrassing.. no one can figure it out
 

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Discussion Starter #5
snik - 2/22/2005 6:59 PM

I have the exact same problem on my 88CE, its hard to start when warm and shakes when in D and idling to the point that its noticably embarrassing.. no one can figure it out
Yep, that's the problem. It's funny whenever I take a girl out, she always comments on how my car "is about to die".
 
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