i had to put on a good 4 or 5 inches of wire on them so that it could go back to the other spot. but like i said before the lights been on since i got the header. and that was a good 2 months before i got the high flow cat and cat back put on.

 

Yeah, you'll probably have to replace the O2 sensor. Make sure to pull the CEL codes, clear the ECU (remove 7.5A BACKUP fuse under hood), drive car, and then pull codes again when CEL returns. Post repeated codes for more feedback.

 

actually you CAN extend o2 sensor wires, but it's very tricky to do. I did it when i installed my header on my DX and i didn't get a faulty o2 sensor CEL once everything was installed, i just got an efficient cat CEL since there wasn't a cat at all.

But your problem definitely isn't a "tune". How do you have the o2 sensors hooked up? Do you have the one that was right in the top of your old manifold plugged right into the front of your new header? And do you have your secondary one extended and plugged back in? Thats how they need to be, but just pull the CEL and i imagine it probably has somethign to do with the extnesion of the wires.

 

well i just used the stock one and didnt use any extensions on the o2 sensor in the header, its the second one that i used extensions for. the cat i bought had two places to install the o2 sensor, and i had to move the sensor because the part that was sticking out was right against the shifting fork and i had trouble getting into 4th, 5th and reverse. so i put the extensions on and moved it to the other side so it wasnt against the shifting fork.

 

ok so i actually just fixed the idle problem i think. i found the control screw and messed with that and now its idling at about a grand

 

maybe you messed it up doing the install of your other parts or when yu were tinkering around in there ^

 

In my experience, you can adjust the idle screw of 6th generation Civics (96-00) to a wide range of settings and the engine still idles properly because the ECU and IACV are able to compensate for enormous variations in air intake. This may indicate that your IACV is a little dirty and needs to be cleaned.