I have a '90 240 with the stock SOHC motor, and just recently it started acting up. Its been running bad from almost idle to about 4000rpm. Its bogs, hesitates, and it seems like its mis-firing. I have changed my sparkplugs,distributor cap and rotor, fuel filter, maf sensor, and temp sensor. I also checked and reset my timing to 15 degrees. But it still runs like poop. Does anyone know whats wrong, or how to fix it? I am in a real slump here so any help would be awesome.
i’d check spark plug wires and fuel pump. Now you would be thinking why would it be ok at high rpm but not middle rpm? If the fuel pressure is very low from the pump, it would run OK at high rpm because the injectors are open for longer - however not making near the power it should.
How is the car above 4000rpm? smooth but low power or entirely fine?
Try another set of sparkplug wires if you can get your hands on them.
Once i hit 4000rpm it seems to run perfectly fine, my torque comes back along with the power. Ill see about the sparkplug wires I am going to put a set of accel 8mm wires on. Also i was talking to my shop manager and he said it could be my egr system, it my be sticking cuz of dirt or just faultly from the amount of kms i’ve put on in such a short time. we will see, i’m going to work on it this weekend so ill update as soon as i find something out, just incase this happens to one of you guys.