: Can ECU "adapt" to certain mods like exhaust?

07-02-09, 08:27 AM
As I have stated in an earlier post been having problem with check engine light and header application. Code p0420. With WFM hanheld though I was able to delete code on Mon night but it came back Tues along with CEL. This morning though I woke up and.... no CEL! Usually stays on until cleared.

Could the car adapt to the headers?- running WFM max perf tune originally set for WFM 3-inch exhaust

Thx for responses in advance

07-02-09, 09:23 AM
Is the outside temp hotter where you are today when you started the car vs the other days?

07-02-09, 10:00 AM
MB- car was in garage overnight- CEL has come on generally after car has been running a while BUT AFTER I HAD TO MANUALLY DELETE CODE

AR Headers informed me that some people/cars have no CEL even without a tune

Even someone with WFM exhaust is throwing a p0420/CEL per my other thread

07-02-09, 03:02 PM
o2 sensors from my knowledge are controlled by the temp of the exhaust gas and how fast or slow it reaches the expected temp. The cats affect this temp and the speed to which it gets there and through algorithms in the ECM determines if the cats are working efficiently or not. With high flow cats, this "speed of temp" is affected and a code gets thrown. Every o2 sensor is different, so I'm sure some are more sensitive than others, etc. Thus one car throwing a code and one not. I'm really confused as to why Jesse won't turn off the rear o2 sensors (Not doubting his knowledge because it is vast for sure). Every car I've ever had tuned with ODBII, the tuner would turn them off. They're useless. Tuners turn them off so peeps can avoid this type of issue and not have to look at the "little yellow engine" on the dash.


07-09-09, 08:38 AM
I was wondering with hearing all the suggestions of turning the rear sensors off for tuning of how the vehicle will behave down the road when it is time for it to go through state emissions inspection. Someone please educate me on this.