It is a smooth idle most of the time. It will do more of a sputtering on acceleration around 30 or 40 or 50MPH. It will not do it all the time. Now the codes do not render anything clear. I get codes for 2 oxygen sensors.(No problem). I get one now for a ATC code but the car is not running extra hot and warms up on time from a cold start. I do get one for a bad Catalytic Converter. If it is the catalytic converter do you replace both or just one. If one which do you pick? I had it tuned up just 20,000 ago new plugs. There is no codes showing for a misfire on any cylinder. I am getting ready to run some Sea Foam on about 8 gallons to hopefully see if that works. I appreciate your feedback.

 

What year, what engine, what codes ?
I believe the ATC code is related to the heater and AC system.(Automatic temp control)
Need all the codes to possibly offer any useful suggestions.

 

Here is what I have and please revisit the question. Codes P0430, P0153, P0125 these are the ones that were provided. It is a 4.6L V-8 2000 Crown Victoria. It is not running hot according to the temp gage. Idles smooth problem is noticed during normal city driving accleration. Upon reaching cruising speed no sputter. When cold no sputter at all when doing city driving - typically happens after car warms up. thanks for the feedback

 

170,000 uses no oil I meant to add this earlier

 

If the code P0125 is fresh it could mean the engine thermostat is stuck open.
Suggest you confirm that and check the thermostat or replace it and go from there. It should be a 195 degree thermostat.
Because the possible thermostat problem could cause the other problems, suggest you take the codes one at a time and clear the computer after taking care of the thermostat and take it for a test run.

 

Hanky it is not running hot and it heats up as expected. Am I missing something here. What about the coils? It only happens after it has warmed up.

 

Bear with me a minute.
If the engine thermostat were stuck CLOSED it would overheat.
If stuck open, it could have trouble reaching the correct operating temp that is required to permit the system to go into closed loop and allow the computer to control fuel and emissions. The codes indicated these problems were present. Many V8 engines will get warm even with the thermostat stock open, but not hot enough for the computer to control the system as designed.

 

Don't know if this will help, but Ford used to run 2 coolant temp sensors on their engines. 1 was for the temperature gauge and 1 was for the emission system. Somebody here may know if they still do run 2 sensors. If that is the case, then you could have a bad sesnor for the emission system while the temp gauge works just fine. I had a problem with my 1983 LTD 5.0 that was running rich. Gauge showed temp OK. That's when I learned about the 2 sensors. The coolant temp needs to be around the 210° for the emission systems to work properly.

 

Hey got it figured out I put What do you coil on it and it runs fine. I totally agree that with you there is still a thermostat issue. Temp is running fine no overheat and it warms up great. There is one weird thing that does happen in the summer and summer time only. After running the car at 65MPH for 30 minutes. Say I need to stop for 5-10 minutes while the car is hot. I crank it up and it immedately goes to a low idle where it appears it is ready to die out. What do you think ?? Is this related to the temp sensor or thermostat? It only happens in hot weather.

 

Hanky - thanks for your help. The sputtering stopped when I replaced the ignition coil on cylinder 4. The P0125 code I have not addressed. It was 25F here today and the engine was cold. It started blowing warm air after it had run for 4-5 minutes. Now typically the electronic temperature readout when fully hot has 4 bars registering on the digital display of my 2000 CV LX model. It has been showing 3 and flickers to 4 now and then but usually reads 3 after 30-40 minutes of interstate running. Look at the post below regarding the other problem I have in extremely hot weather. Most of all THANKS