93 Crown - runs rough until warmed up - HELP!!!

[ojo7997]

I've got a 93 4.6L Crown that runs rough/sputters when first started in cold weather (45-50 degrees and colder). If driven without being warmed up, it doesn't accelrate well and is very sluggish until it is warm, and then it drives fine. Puts out a LOT of exhaust at first, then it tapers off to a normal level. I've already changed out the spark plugs, fuel filter, air filter. Now I'm looking at the EGR, o2 sensors, etc, but don't want to waste money on swapping out stuff that's not broken. BTW, the check engine light is on.

What could possibly be wrong with this vehicle? What should I be looking for?

[TENGRAM]

Originally Posted by ojo7997

I've got a 93 4.6L Crown that runs rough/sputters when first started in cold weather (45-50 degrees and colder). If driven without being warmed up, it doesn't accelrate well and is very sluggish until it is warm, and then it drives fine. Puts out a LOT of exhaust at first, then it tapers off to a normal level. I've already changed out the spark plugs, fuel filter, air filter. Now I'm looking at the EGR, o2 sensors, etc, but don't want to waste money on swapping out stuff that's not broken. BTW, the check engine light is on.

What could possibly be wrong with this vehicle? What should I be looking for?

you need to pull the codes. its very simple. similar to THIS PROCEDURE but of course it would be best to find the procedure specific to crown vics...maybe someone on here knows.

here is the self-test connector location:



once you get the codes post them up here and we can help you diagnose them.

sorry i couldn't be more help. i have much more experience with mustangs then with CVs




edit: here is the procedure i found posted on this site, it looks to be identical to the procedure i posted earlier (although not quite as easy to follow): http://www.troublecodes.net/Ford/

[mike avery]

sounds like bad o2 sensor i had the same problem and thats what it ended up being. take the car to a auto store like advance auto or auto zone and get the code read for free. post your codes because they dont do a good job of determining the codes. good luck

[reekor]

The PCM does not use o2 sensor readings until the engine is warmed up. The PCM runs off of preprogrammed values when the engine is cold, this is called a open loop.

OPEN LOOP

Definition: A mode of operation in a computerized engine management system that occurs after a cold start. During open loop, the computer provides a fixed air/fuel ratio that is richer than normal to improve cold derivability until the engine warms up.

CLOSED LOOP

Definition: The basic principle of electronic engine management in which input from an oxygen sensor allows the engine control computer to determine and maintain a nearly perfect air-fuel ratio. To enter closed loop operation, the oxygen sensor must be producing a voltage signal and the engine must have reached a certain operating temperature.

Originally Posted by mike avery

sounds like bad o2 sensor i had the same problem and thats what it ended up being. take the car to a auto store like advance auto or auto zone and get the code read for free. post your codes because they dont do a good job of determining the codes. good luck

My bet would be on the PCM temperature Sensor

[TENGRAM]

this is exactly why you need to check for codes. guessing can get very expensive very quickly...even "educated guessing"