Hi, I have a 1991 240 automatic with about 180k, and it is dying while at idle or at lower speeds - but only when the weather is particularly warm (over 80 degrees).

What typically happens is this: I will be idling at a stoplight, and the RPMs will begin to drop until the engine dies, leaving all of my dash lights on. After this, I can always start the car again immediately, and can usually arrest the dying process altogether by applying a slight bit of force to the gas pedal while at a stop. Occasionally, the engine will also die at low speeds - under 25 mph, though again only when it is a hot day.

Interestingly, the engine sometimes will momentarily die about a second after starting from a stop, but it will mostly spring back to life if I push very quickly and firmly on the gas pedal. This feels like a hiccup - a momentary loss of power followed by a surging engine.

This might be noteworthy or not, but it is also giving me codes 2-4-1 and 2-1-4: EGR system faulty, and speed sender faulty or signal missing, respectively. I should note that this problem has existed for years, while these codes have not. The Haynes manual says that an EGR code will be given every 15,000 miles, and my car just rounded 180k fairly recently, so these might coincide. Also, I believe that my overdrive solenoid is bad (no 4th gear, and the solenoid failed the diagnostic tests I gave it), which could maybe(?) have given me the speed sender code. It is also noteworthy that my car is accelerating poorly, and is experiencing poor fuel economy.

Has anyone had experience solving a similar problem? Any advice would be very greatly appreciated!

 

the 'speed sender' is likely the crank shaft position sensor, has nothing to do with OD, and everything to do with engine operation. its wiring insulation can go flakey, leading to random stalls, hesitations, etc.