So I Finally came to my senses. :)
 

Sold the W140, and bought what I really wanted. A 560SEC. It's awesome, but it has some issues (of course!).

Anyway, here are some pictures.

http://img.photobucket.com/albums/v2...1/IMG_5747.jpg

http://img.photobucket.com/albums/v2...1/IMG_5749.jpg

http://img.photobucket.com/albums/v2...1/IMG_5743.jpg

NICE!
How many miles on her? The seats look like they are in excellent shape

Lucky!!!

Haha, thanks! The car has 113k miles on it, but the odometer was swapped so it reads like 189k or something. I have the original odometer in my possession.

The seats definitely look great! The back seats are a bit faded tho. The main problem with this car is that it runs like crap. It will sometimes idle ok and accelerate smoothly, but other times it will act like it's going to stall, and a couple times already I have gotten stuck in an intersection and the car wouldn't move...I put my foot all the way down, and it doesn't respond for a few seconds (engine just shakes and bogs) and then all of the sudden the tires are spinning. It's very strange. It also won't accelerate smoothly, like there is a misfire.

Also, the o2 sensor light comes on on te dash every oncein a while...what does this light mean?

Nice! Despite their age (and ultimately issues that need attention) I would snap one up if the body was in good shape!

And that is a nice interior!

Sounds like one or more ignition-related items are plaguing your car. I'd start with a full-circle tuneup, then replace the spark plug wires (ask me what plagued my W124 ills for the last year)!

Up next, replace all vacuum hoses. Then see what happens.

O2 sensor is probably good for 200K, but probably due for replacement anyway. Other than improved gas mileage, I don't think its the source of your performance issues.

Congrats on your find!

I am not so sure about the O2 sensor. If it is going bad, it could affect the idle and could be causing the car to run way too lean when he steps on the gas. That is what happened on my 528e. I believe the fuel injection system is pretty much the same on the MB as on the BMW.

Try unplugging it. That will send the system into open mode and the fuel injection will work against the pre-programmed maps and not try to fine tune the fuel. I did that and the idle problems went away and it accelerated better. I still have to get around to pulling RnRing the sensor.

Where is the sensor connector located on my car? Under the passenger carpet?

Should be before or after the catalytic converter.

Nice find, too bad you had to sell your W140.

You're not selling your 300D, are you?

The diesel is sort of up in the air right now. I love the mileage it gets, but I don't need three cars lol. Only time will tell.

Any ideas for a name for this beauty? I'm having trouble.

Looks like it has black pearl metallic paint. Our wagon has similar paint, I called it the Black Pearl :D

That's perfect!

Very nice. Love the w126:)

How are the idle control valve, the fuel filter, O2 sensor, fuel distributor, spark plugs, and the catalytic converter?

I replaced the spark plugs and wires, and it seemed to really help the acceleration and hesitation problems. (WOW, this thing is fast!) But it still has a rough idle, and is making a ticking sound, almost like it has an exhaust leak. The sound goes away at higher RPMs and the engine revs very responsively and smoothly. I am thinking this is probably a fuel issue.

My local MB indy shop said that one or two cylinders aren't firing properly (duh). I'm going to drop it off there tomorrow morning and they are going to diagnose it. Hopefully I can get some answers that way. He said they would do a compression test, then check the fuel system.

89' 420SEL has same problem
 

Let me know what your mechanic says.

Mine 89' 420 SEL has same ticking noise (Like exhaust pipe is broken) at idle and goes away after reaching higher RPMs.