88 560sl idle and missing and hard starting

[kennedy]

problems started out as hard starting after sitting for an hour, so I changed the fuel accumulator, did not fix
new problem also when hot, put in neutral will some times rev up to 1400
new problem also when hot, going down road, will start missing and clouds of black smoke out exhaust, then will clear and run normal, this first started as a problem after hard starting, high revs and when pulling out of parking lot, no power and lots of back smoke
help
The only other thing I have done to it is cleaned the air slide valve, Is this also called the idle control valve? thanks

[rocky raccoon]

Sounds like ECU related problems. In the case of my 88 560SL, the culprit was the sensor that inputs engine temperature to the ECU. It was easy to change that accessible and relatively inexpensive sensor. Try to isolate your fault before simply changing every high dollar item in sight.

Yes; idle control valve. Cleaning it was a good thing to do.

[kennedy]

Is the ECU the computer, and which temp sensor, there are several, where is it located? thanks for your help

[rocky raccoon]

Yes. ECU = engine control unit = computer.

The temperature sensor I referred to is at the front of the engine just under the leading edge of the air filter housing. It has a green body and is the one with two wires attached. The other two are for the temperature gauge and the auxiliary fan.

Remove your air filter housing to access it.

Let us all know if this works out.

[kennedy]

Is it in a water passage, if so, do I need to drain coolant to change it?

[rocky raccoon]

The element is in coolant but can simply be unscrewed and replaced using a wrench without losing coolant.

Understand that this may not be your problem. My symptoms were very similar to yours and it worked for me.

[kennedy]

found it, I think, will need to buy a socket to fit, it has two individual wires going to it, each with its own connector.