94 400E strange issue after sitting for a while.
 

I have one for you! If my 400E sits for a couple weeks, it runs great for the first 10 minutes or so, then starts missing, backfiring, stumbling. After you run it this way for a bit and shut it off, let it sit for hours to cool off, it is fine from that point on. Start it the next day and run it, it is fine. Only after sitting for a couple weeks will it do it again. I thought maybe the gas cap wasn't venting right causing it to build up a vacuum in the tank, but that wasn't it. Anyone have any ideas, or experienced this?

400e sitting a while
 

I had the same problem over the last few years with my wifes 400e, did everything , plugs , injector cleaner etc , it was the distributor caps and rotors, pull them off and examine them , probably trashed about $170.00 on ebay , $200 on ******** for both sets

Thanks! I'll check that.

I second what jollygreen said. It is probably the caps and rotors. Classic symptoms. What I have found is that moisture will make its way up into the caps and corrode them if the car is not driven regularly, especially if you are in a humid climate. Driving the car a lot may clear up the problem, but it's best just to replace them. Cost is pretty high, but if you shop around, you can get the Bosch part (exactly the same as the MB part but without the 3-point star) for a lot less. The good news is that they are very easy to replace. It takes me a very leisurely 2 hours to do both sets. Might as well replace the plugs while you are in there too, since the plugs should be done every 30K miles also.

The caps and rotors are about the only semi-weak spot on these cars. Most frequent cause of driveability problems I've found. I say semi because all that's really needed is to replace the caps and rotors every 30K miles and you are good to go. Slightly higher maintenance and expense than the later coil pack E420's, but not bad at all. These are still awesome motors. Driving the car regularly helps too.

That makes sense. What is absolutely weird about it though is that after sitting for a couple weeks, it runs fine for the first 10 to 15 minutes, then acts up. What I'm going to do is let it sit for a bit, then pull the caps and see what they look like like. Maybe it does build up corrosion or something. I'll then replace them and see how it does also. I'll update the thread in a couple weeks!

Just as an update... Replacing the distributor caps and rotors resolved the issue. They did look horrible inside!

Great! Now just be sure to drive that 400E often and you should be good to go another 30K. :)

Wow, I'm amazed. I've heard others say 30K replacement intervals for these, even on the 104 engines.

All I can say is that my (104.980) originals did around 200K miles with regular cleaning. Even when I replaced them I noticed no difference until the cheap rotor I bought failed.

Now I'm on MB parts and expecting another 200K!!

Best to all.

RayH

You can stretch them a lot longer than 30K by 1) regular driving, and/or 2) periodic removal and cleaning of the contacts. If you don't do enough of either, the MB recommended 30K replacement interval works wonders. :)

My car is doing the exact same thing lately even sent out the throttle body for rebuilding, and they said it was fine!!! I've had it towed 3 times, ordered caps and rotors today!!!