NEED HELP! put headers,cold airand cat back exhaust car does not run good .What do I need to do???????

 

First off, WHAT is not running well and then DEFINE not running well. Noises, hesitations, what? Can't help without the problems.

 

spitting and sputtering in 3rd 4th and 5th gaer at steady rpm

 

did you reset your ecu?

 

Bingo. You hit the nail directly on the head.

Also check for leaks in the connections. A leak in the intake may be sending a bad signal to the sensor. A leak in the exhaust can send the wrong signal to the 02 sensor. Just double check your work and reset your ecu.

 

i would start where they have stated if that doesnt help make sure you did not loosen a vac line as well.

Had one do the sale thing (with out mods) and it was because of a vac line had come loose

 

that's what i was thinking was a vacuum leak. best way i've got to discover a vacuum leak is a can of wd-40. Just run the engine and spray on any surface that should draw in air. if the engine gets worse on one spot, you found your leak. Not sure how well that'll work on something newer though. It worked like a champ on my old jeep.

 

Don't use wd40. Use some soapy water. It will bubble up and you can more accurately see the leak.

 

Try this to reset you ECU https://www.scionlife.com/forums/viewtopic.php?t=33062 then try the soapy water.

 

Question.......Which scion do you drive?