Alright, so I installed my DC header, and 40 miles later i get a CEL. So I do the ol' non-fouler trick and all was well for a while. Then after 450 miles it came back. Since it took so long to come back I took my car the the auto store and scanned it to make sure the O2 reading was the real problem. Sure enough it was and I deleted to code so that i could have another 40-400 miles without having to look at that annoying light . So I was wondering if anyone had any thoughs as to why it came back. Also I want to know: if the CEL is lit and i drive for a while with it untill I can deal with it, am I hurting anything?

Im not sure if any of the following facts are relevent but consider:
-Its an 08
-Its cold out
-I didnt use HELP! brand but rather some other brand that the store happened to carry
-The rest of my exhaust is stock
Toyota just put on a new tire for me because one of mine popped (I dunno, maybe while it was up they noticed the non-foulders and took them off, I'll check tomarrow)

I know my toyota theory is pretty unlikely, bu you never know.

Also I thought a possible solution might be to actually plug the hole of the undrilled non-fouler with a small screw and a nut.
When I was talking to people at the auto store and I mention my possible solution they said it would confuse the engien sinse it wouldnt sense any thing and I'd run lean. Is this true? I though the upstream 02 sensor handled air/fuel ratio monitoring and the downstream one only sensed for 02 but correct me if I'm wrong.

Sorry for such a long post but any help would be great, thanks.

 

just reset the ecu again.

 

You think it was just a fluke that it sensed anything?

 

my CEL came back on once, i reset it and hasn't came back yet.

 

cool I hope it stays off this time

 

Plugging the hole of the anti-fouler would probably throw a CEL almost immediately (with a different fault code) because the electrical output of the O2 sensor would never change and so the ECU would consider it "faulty".

You would not run lean (and if you ever do there's another fault code for that too) because, as you said, the first O2 sensor on the header is utilized as the air/fuel ratio sensor. The sensor in the s-pipe has only one purpose, to monitor the efficiency of the catalytic converter in the (now removed) stock exhaust manifold. You didn't mention the fault code they read for you at the parts store but I assume it's P0420, which = low cat efficiency. If so then no, you're not hurting anything if that's the only code you're throwing.

 

i got an 08 as well, with a dc and the light comes on and off at radom times, a friend of mine pulls his batt cable to reset his ecu on his srt4 every friday to never see a light, but i have noticed that the light will stay off for about a week, then come on for maybe a full day, and back off, so i dont even mess with it. its gong to happen, until either the ecu reconizes the change, or you install some sort of piggyback to go in there and adjust stuff, you're going to see a light, only difference is its not on all the time like it was before the fouler trick

 

Thanks for the info

 

I see... Well my CEL did just come back after 95.7 miles. I just took off the neg cable to reset the ECU again, i'll see what happens and update. If it does come back, I wont reset it to see if it goes away and comes back like yours does.

 

how to do exactly reset your ecu btw?

 

just remove the ECU fuse from the fuse box. its a lot less trouble than disconnecting the cable.

 

i got the DC header on my 07 tC and did the anti fouler trick and it worked for a hunderd miles or so, and then the check engine light came on for the rest of the day driving. i was like great! the anti fouler trick didn't work. so i'll just clear it tomorrow at work then..............well............when i woke up then next morning, i noticed the check engine light was gone.......wtf? i got to work and hooked up the techstream (AKA skan tool) and noting the check engine light was not lit on my cluster, there was infact still an active "current" code for a catalist system defficiency...........

i don't know how that happened but it remains an active code to this day yet my check engine light is not on......

 

wow thats weird^^

 

Wow i thought this thread was long dead. Well anyway I finally found a solution that works for me. If anyone else's CEL is as stubborn as mine was, check out my DIY: https://www.scionlife.com/forums/vie...682f13065aeb9c

 

how many foolers u guys using? because the cel came back for me with the two foulers.. i installed the third one and the cel never came back since!!!! so if u have problem then its really EZ: install a third fuler on it!!!!


sensor | non modified fouler | another non modified fouler | modified fouler | s pipe

 

lol i think you mean
sensor | modified fouler | non modified fouler | another modified fouler | s pipe

this works for a lot of people, didnt work for me though

 

pfff.. both is wrong!!!!

this is the good list :

sensor | modified fouler | non modified fouler | another non modified fouler


you DONT need two modified fouler!!! you need only ONE!

try this. should work... if not.. try that L shape fouler...

 

lol yeah thats what I meant, hah neither of us can type

 

so u did it with 3 fouler and it wasnt good???

 

no it didn't but look at the thread I linked to above. Its a DIY explaining a solution I thought if that did work for me