Picked up a 1987 MB260E for a song. When the vehicle is warmed up, it experiences a hesitation problem when moving off from a standing start. Once the car is cruising, no problems whatsoever. Funny thing is, when the engine is cold, it doesnt have any hesitation problem. I had a hunch it might be a fuel problem, so I removed the injectors to clean them and visually inspect them, they look okay. I used carb cleaning and compressed air to clean them, and they seem to spray a nice mist. I also changed the fuel filter. But alas it didnt help. I checked the spark plugs, they also look okay. I cleaned all the connectors I could find with contact cleaner. I even cleaned the battery terminals and all the grounding points I could find. But still no luck. This vehicle doesnt use any O2 sensor or CATs. The only sensor I could find was one mounted on the air intake, looks maybe like an IAT sensor. It has the strangest fuel injection system, and strange devices mounted on the intake manifold. Here is a pic:

http://web.singnet.com.sg/~kppjw/MB260E_Engine.jpg

Comments appreciated.

There is a cold start valve which is supposed only to supply gas during cold start up phase. If it leaks it will cause the engine to have rough idle and pick up problems. You will find it on the non-driver side of the block it has a blue or green plug (Your car is English, right?). Just take it out and see whether or not it leaks. It shall not be wet at all. Another cause maybe extra air entering the system. Try to spray the running engine with brake clean fluid on the intake aseembly, the injector seals, and the vacuum hoses. The spraying shall not cause the idle speed to change (unless you spray into the intake direcly). If it changes there may be a point where extra air is allowed to enter the intkae system. Also check if the vacuum line to the power brake container is mounted tight and sealed. Of corse there are many other reasons for the problems you describe, but these few are simple to check.
BTW: this is not looking weird at all, this is how 260E's look like.

Problem solved! It was a leaky cold start valve as you had suspected. I disconnected the electrical harness and plugged up the fuel line to permanantly disable it. Hopefully I wont have any cold start problems. It's always hot here in Singapore, >30C.

Thanks for your expert advice!

Hi Ken4,
I've been in Singapore quite some times, and I guess you're right that you may not have any coldstart problems. The worst I expect is, if you may have temperatures falling below 15C, you may have to cranck 2-3 times to start, but so what??

[QUOTE]Originally posted by bamberger_1
[B] Try to spray the running engine with brake clean fluid on the intake aseembly, the injector seals, and the vacuum hoses.

bamberger,
I have similar problems.

Isn't it harmful for the seal and engine to spay Brake fluid ?

I think he meant brake cleaner. You can also use carb cleaner.