Replaced Thermostst Now Won't Run Right.

I replaced the thermostat and coolant now the car acts like it's running on 4 cylinders. It's a 1992 3.1. The car ran fine before I just can't figure out what I did. Its real hard starting ,runs extremely rough.and the cooling fans are coming on when cold. Disconnected the battery to to reset the computer. pulled the codes got 45 (rich). Any Ideas?

Without looking over your shoulder for what you may have done or not hard to tell, check for any disconnected sensors, coolant temp in particular.

I replaced the thermostat and coolant now the car acts like it's running on 4 cylinders. It's a 1992 3.1. The car ran fine before I just can't figure out what I did. Its real hard starting ,runs extremely rough.and the cooling fans are coming on when cold. Disconnected the battery to to reset the computer. pulled the codes got 45 (rich). Any Ideas?

the ignition wires should be checked. did you get coolant over the engine ? also look for hoses disconnected as well as any wire connections.

I believe the coolant sensor is on the radiator. make sure connector is on .

fans coming on when first starting point to the coolant sensor circuit.

improper computer engine temp feedback would cause a hard start.

Thanks for the replies..It turned out to be a bad fuel regulator. Had nothing to do with changing the thermostat. Weird, It was running fine until I changed the thermostat and the first start afterwords it was running bad. So I assumed I caused it. What a PITA this one was. Thanks again..

Maybe you accidentally broke the vacuum line to the FPR? That'll make 'em do what you described...so will breaking the ground for the coolant temp reference to the computer...nails them full rich...I was gonna suggest maybe you didn't reconnect it, I seem to remember it grounds at the thermostat housing on the old ones...

I replaced the thermostat and coolant now the car acts like it's running on 4 cylinders. It's a 1992 3.1. The car ran fine before I just can't figure out what I did. Its real hard starting ,runs extremely rough.and the cooling fans are coming on when cold. Disconnected the battery to to reset the computer. pulled the codes got 45 (rich). Any Ideas?

I am about to change the thermostat on my 96 3.1L Lumina . It is in the housing under what I think is the throttle body ?

Was it hard to bleed / burp the air out ?

Wish me luck .

God bless
Wyr

Hey, JeffCo -- Google sent me here when I had the same problem. The vacuum line it was. Thanks!