1985 318I bmw idle is high what do I need to do

Your engine is controlled by the PCM. The idle can be adjusted by entering the computer system using INPA with a K+DCan cable, or the BMW diagnostic system. If by chance it's too high, look for a vacuum leak. Generally speaking if you are careful, you can use a can of carb cleaner (carefully) by spraying a small amount at a time near the vacuum hoses and the intake manifold of a vehicle to find the leak. As the carb cleaner is drawn into the engine the car will change idle speed to help you zero in on any leaks. Too low then there must be a fuel/air issue and you should have a code present. Good luck:)

There is no cold start relay. Cold start mode ( open loop, rich, high idle) is controlled by the ECU. A coolant temp. sensor signals warm up to shift the ECU to closed loop mode(warm, lean, normal idle). Check the coolant sensor and correct coolant level. The thermostat controls warm up time.

Where is it throwing sparks from, under the hood, under the transmission, from the alternator, etc.? Since the idle speed could be related to some load that is generating the sparks, I wouldn't treat them as separate issues yet. But you need to do some troubleshooting and provide more information for anyone to give you a decent answer.

take it for a run on high way
high speed, low gear to clear the emmision

I think the IAT ( inlet air temperature) sensor is at fault, check whit with a code reader or scanner

I would check the idle air control valve. The computer controls idle speed by regulating the amount of air entering the throttle body by using the valve. It could be sticking or failing.
I am assuming you have a 93 Monte Carlo.

Usually it is a sticking throttle plate, vac leak, or a problem with the idle control valve.

Hi, all you need to do is replace the engine breather valve on the intake manifold and the problem should be sorted.

it's not old carbureted chevy, it's not idling high because there's too much tension on the gas pedal cable.

look at replacing/cleaning: idle control valve, maf(mass air flow sensor) vacuum leaks: intake manifold or air intake system.

If is for a 3 series compact (318ti most common) then
P2799 is the intake air tem sensor 2
Which would explain the high idleing. Probably a sensor problem (bmw will charge) a competant mechanic should do it easily.