964 back fire

[Cedric 18]

My car has been acting up last week, here are the symptoms and what I have done so far:

Car doesn't have the power it used to have, feels like the timing is off. Sometime I step on the gas and it's just flat, cars coughs up, then it goes. I have a Hall sensor and oxygen sensor fault when reading the codes. Oxygen sensor is almost new. Car back fires. Looks like it lets unburned gas out of the exhaust, lots of wet spots on my back bumper and back lid. I checked a few things:

unplugged each coil, on one of them it runs fine, on the other it back fires and engine shakes. So I decided to replace both coils and the ICUs, still the same. Check wire from coil to distributor and they are fine. Checked all spark plugs wires, fine, sparks plugs are a year old.
Could a bad hall sensor cause this? could it be my distributor?

DME relay, ECU unit have been checked, new speed sensor on flywheel, new distributor caps.

Thanks for your opinions!!!
Cedric

[Boydyrs]

Make sure you have the correct bosch lambda sensor and not aftermarket

[crg53]

Did you swap the coil leads from primary to secondary distributor to see if the problem follows the coil or distributor ???

[mystert]

Backfiring means your timing is off and the ignition is firing on the exhaust stroke. Check the distributor belt, it could be broke/frayed/slipping causing the ignition to fire out of time. If it runs fine on one coil but not that other I would think that's the issue.

[RedCoupe]

+1 on broken distributor belt. Easy way to check is to pull both distributor caps off and see if both rotors turn when you push the car by hand with the transmission in 4th or 5th gear. If the belt is broken, only one rotor will turn.

[Cedric 18]

thanks, I did switch the coil wires and it follows the coil. I will check the belt in the distributor tonight.

Cedric