Failed Smog

[boyRD03]

Hello Everyone,

My car just failed smog due to high NOx @15 MPH. My HC measured were high but within parameters. Ive done plenty of forum and google searches just want to here what everyones option is. I just finished installing the rebuilt engine. I had the injectors cleaned and all new plugs, wires, and ignition coil and O2 sensor. I'm hoping it's not the CAT but that's the only thing that makes sense to me right now. Any suggestions would be appreciated. Thanks

[reelizmpro]

Did you get the CAT nice and hot before testing? Post the numbers.

[boyRD03]

Yeah drove the car for 30 mins and let it idle for another 15 mins before test was done. HC measured 109, max 114. NOx measured 1050, max 785. CO measured 0.16, max 0.73. This was done @ 15 MPH, Test @ 25 MPH passed. I did notice the temp gauge was a little higher than the 12 o'clock position. I may have some air bubbles that I need to bleed from finishing the rebuild. I also ordered new Idle Control hose because mine looked like it was cracking but all other hoses are new.

[bmwman91]

Original cat? If so, then that is your issue. A Magnaflow weld-in replacement should run you under $300 installed. I have gone straight from having one installed to passing SMOG with near zero numbers a number of times.

[boyRD03]

Its not original the PO had it changed but that was over 15 years ago. I was hoping its not the CAT. I called a couple places and got quoted $485 at both.

[ScottSneed]

Likely the cat, aftermarket cats typically don’t have as much precious materials and don’t last as long especially when poisoned. SWIM, got a friend to receive a high quality federal (48 state) cat (bosal iirc) and then had it shipped to him. He found a smog guy that could careless to run the cats numbers and passed easily..