Can my car be throwing codes without a ses light on

[MustangLife]

My cars driveability is just not smooth anymore since I set it back to stock. flows and k&n are the only hp mods right now. I had a off-road x-pipe, cold air intake, diablo chip, 4.10 gear, pulleys, and a 160 thermostat.

Now the cars idle is not very smooth anymore, not a fluctuating idle, just a rough type idle that not really effects the rpms. Also when the air is on, the idle fluctuates.

When driving it seems to have a hesistation or bucking type feeling. My car is not throwing any codes. But about 5 weeks ago it though a code for about 1,200 miles and than went off one day. I have ngk tr-55 plugs with about 3,500 miles on them.

Anybody have any thoughts
Josh

 

[03gtmustang]

Could this be another case of a bad MAF sensor???

 

[bdcardinal]

seems like the theme of the day. it can very well throw codes and not show a light. generally they are 2 trip codes, meaning that it has to happen twice before lighting the CEL. did your problems happen after reoiling the k&n? overoiling it can gunk up the maf and cause bad things to happen

 

[MustangLife]

My k&n has never been re-oiled