So when I purchased my 07 Civic Si there was a Cel. The PO had it checked out and it was running lean. The flange on the downpipe below the shitfter had disconnected/broken off. I took it to a muffler shop and they fixed it. The cel was still on when I picked it up. After i parked it for a while and drove again the cel was gone. 2 days later it returns. So I took it to honda for them to see what was wrong. They said its the o2 sensor or the o2 sensor harness. So they're suggestion was to replace the 02 and harness. Which I know that was possibly the issue but I wanted them to have more of an idea. Which put me out of $107. So they cleared the code. 3 days after taking it to them the code has returned again. Even when the code wasn't there the car died while turning a corner and had idle surges here and there. Could a bad o2 all of sudden work with no issues then resetting the code fix the issue temporarily? When the honda tech said replacing the 02 sensor and harness did he mean just the wire that connects to the o2 sensor? Only mods on car is a cold air intake and exhaust. Would I be ok with just a oreilly o2 sensor with 1 year warranty?

 

Alright so the CEL went away on its own. I'm really confused now. Anyone else ever run into this issue?

 

Ttt

 

do you have any pics of the re-welded downpipe? A cold air intake can make the CEL come on. You should get the flashpro and get all the performance goodies together before throwing in the car.

 

I took it to firestone. Then they referred me to a exhaust shop because the type of material needed to be welded. I guess why would you need a pic? I purchasedon't the car with cold air intake. Doubt I'd do more to it. Cel hasn't came on for a while.

 

Just to see the welding job they did. But most definitely the CEL is because of the CAI. I had a INJEN CAI in my Si and I never got a CEL but the car would not run right at higher RPM's when pushed. It would stumble a bit. I removed it and installed stock airbox back on and modified the resonator part of it (basically opened it up) so it would work like a CAI. Threw in a K&N filter and the car ran great.

 

O ok. Well if i ever get it jacked up I will take pics. I guess it was the flange or something that snapped off? Was only $45 to repair. Yeah the rubber fitting of the cai attaches to throttle > Tube Rubber fitting with MAF in middle > Tube > Rubber fitting > Filter. The Filter leads to the front behind the bumper. Not sure if its a good place though.

 

Thats the usual CAI. Just be careful when driving over deep puddles, you can hydro-lock the engine. Another reason that I removed mine was because is a pain to get to the filter for cleaning.

 

Ok. Yeah rain season almost here. I'm also wondering about these hoses from the block to the intake. Both hoses are connected to this medal connector then another connector on top that both ends don't connected to. Hope video helps...

https://youtu.be/VmFvSBptB0U

 

That metal pipe is used with the stock airbox, the hoses that are still attached to it are coolant hoses. Honda uses it to cool/warm the gases from the valve cover evap hose, which is that top red hose thats connected from the valve cover to the CAI pipe. I never really understood the purpose of it though.

 

so basically i can remove that metal tube and directly connect the hose from the intake to the block? Because that top medal tube has both ends nothing connected to both ends but the bottom has hoses connect to it.

 

Yup... If you get a hose make sure its coolant resistant.