I install HKS hi-power exhaust, megan racing header + downpipe. The next day, the engine service soon light came on. What should I do??

 

You got the CEL from the downpipes. You need something to fool the secondary O2 sensors into thinking there is a cat still there. Get an O2 simulator of some kind, or use the non-fouler solution. Do a search on those.

 

Use four nonfoulers for spark plugs 18mm in the second set of o2 sensors in the down pipes/test pipes. Two on each side,drill out the first nonfouler with a 1/2in. drill bit for clearance for the o2. Screw it in the second nonfouler undrilled then in to the down pipe/test pipe. This spaces the o2 away from the exaust gas and trix the ecm/computer to thinking that the the cats are donig there job. You can get the nonfoulers in the help section at the local parts store. Get the ones with the copper gaskets for a flat seat not a tappered ones

 

thx for the advice, I get nervous when at first and forget to do a search for solution. I did a EUC reset today, and the CEL is gone. I am hoping it will stay that way, if not I will go for the fouler or o2 simulator method. Did this CEL happen to you also? I am thinking if it would be better for the fuel thread if I put the stock cat back on.

 

I had the cel light come on after a test pipe install. I did the pedal reset and the light stayed off. it came back on about a month later and after a pedal reset it would come back on within seconds.

i picked up a set of sparkplug nonfoulers (18mm) for 5 dollars at pepboys. im not sure what DoubleT is talking about with drilling but i removed the rusted bolt holding the o2sensors in the test pipes and put the nonfoulers in as spacers. i did the pedal reset and the light has stayed off.

its a neat little trick that costs dollars and takes minutes to diy.

 

the cel come back on this morning, I will go pick up some nunfoulers tomorrow. do you realize the mpg drop after the CEL is on??

 

YES. other than the fact that the car is running like a limp dick with the cel light on i was lucky to get 220 miles to a tank. now i can get 300+ if i take it easy.

if you have a jack and jack stands you should be able to diy. you want to put the spacers in the o2 sensors in your downpipe/testpipe not the ones up top on the headers that are tougher to get to.

 

yes
i did exactly what you said and cel is gone and milage per tank comes back for 330