Lazy cylinders
 

I am new to the Mercedes world. I recently purchased a 1992 MB 310 otherwise known as a T1. It does not have the original motor in it. I’m told the engine in it is from a 1984 190E. It’s a carburated 2.3 L, M 102 motor with unknown milage. I can not get #3 and #4 cylinders to fire. I checked compression and all cylinders are consistently 148-150 PSI. I changed out the spark plugs, then the cap and rotor, then the plug wires, then the coil, then the distributor, all to no affect. Any advice on where I should go next would be greatly appreciated. Thanks

How was that determined?

Hello Frank, Starts fine, idles rough. When idling I can pull both #3 and 4 plug wires simultaneously with no effect on the engine performance. Pull #1 or #2 plug wires individually, the motor chugs and chuffs and will stall.

Do a compression test on all cylinders.

Are 3 and 4 getting fuel? Did this engine sit for an extended period? Possible that it has a blocked intake runner to those cylinders from rodent nests.