Cat replacement nightmare. Need advice on next steps

[sjmorrow]

My wife has a 2011 V6. The cats went bad right around 80,000 miles, so we bought a set of high-flow cats that were manufactured specifically for the LLT from Solo Performance. The CEL kept coming back on saying one of the cats was bad (P0420 code), so we took it to a local performance shop to have them tune the ECU to make the car pass inspection. The shop tried every combination of emissions tune they had and every single one prevented the OBD state from being "Ready", which means the vehicle will not pass inspection. They are telling me my only option is to buy a set of OEM cats and replace the high-flows. This is going to more than double the cost of the high flow cats.

Has anyone ever successfully put aftermarket cats on their LLT? If so, was there any trick to get it to work? Am I really going to have to pay for OEM cats for $1300 just to get the ECU to allow me to pass inspection? We are 2 months past our inspection date now and have been trying to get the car to pass for 3 months. Im desperate...

[Dizzy82]

http://www.camaro5.com/forums/showthread.php?t=298867

[sjmorrow]

Originally Posted by Dizzy82

http://www.camaro5.com/forums/showthread.php?t=298867

That's a pretty informative thread, however Solo Performance guarantees that the cats will not throw a CEL. Others have installed them with no CEL. It seems we are the first after speaking to the owner of Solo.

Has anyone ever seen a tune that failed to allow the ECU to pass the internal catalyst test? An OBD scan shows the Catalyst and Evap test as incomplete, but all other tests have passed. No matter how far we drive, the test will not mark as complete in the computer

[Eddiefuzz]

Did you replace the stock cats with the SOLOs because of that code? Maybe it's the Oxygen sensors. I've had SOLOs for years on my LLT, although I didn't replace them because of codes. I have a HYPERTECH tuner that can clear any codes. I don't know if that would help your situation.

[sjmorrow]

Originally Posted by Eddiefuzz

Did you replace the stock cats with the SOLOs because of that code? Maybe it's the Oxygen sensors. I've had SOLOs for years on my LLT, although I didn't replace them because of codes. I have a HYPERTECH tuner that can clear any codes. I don't know if that would help your situation.

Yes I did. I had multiple shops tell me the stock cats were shot and needed to be replaced. Buying high flow cats was cheaper than buying OEM, which is what led me to the Solo Performance cats. We have cleared the code about 4-5 times already and it keeps coming back without a tune. With the tune, the ECU just never enters the Ready state because its still attempting to run the Catalyst and Evap tests

[spyder]

Not sure if this would be helpful but sharing it anyway.
I got CEL when I switched to high flow cats, but I also have full length headers so the rear O2 sensors would provide inaccurate information to trigger the CEL etc.

I was able to take care of it with Trifecta Tune. I never got a CEL again for having the headers and high flow cats. Since then I have passed New York State inspection twice without any problems. Therefore, I think you just need the proper tune to take care of the CEL. Good luck!

Edit: If you were local I could have sold you my original cats for a decent price. ~30K miles on them. So if you can't get the right tune for whatever reason then your other option is to check Craiglist/Ebay to see if you can find used OEM cats in good shape.

[sjmorrow]

Originally Posted by spyder

Not sure if this would be helpful but sharing it anyway.
I got CEL when I switched to high flow cats, but I also have full length headers so the rear O2 sensors would provide inaccurate information to trigger the CEL etc.

I was able to take care of it with Trifecta Tune. I never got a CEL again for having the headers and high flow cats. Since then I have passed New York State inspection twice without any problems. Therefore, I think you just need the proper tune to take care of the CEL. Good luck!

Edit: If you were local I could have sold you my original cats for a decent price. ~30K miles on them. So if you can't get the right tune for whatever reason then your other option is to check Craiglist/Ebay to see if you can find used OEM cats in good shape.

That's great news. Thanks for sharing your success story lol. Ill look into the Trifecta thing. At this point Im thinking we just need to drive the car a little farther than normal for the computer to be "ready". I've seen other people having problems with the readiness test and they had to drive it for a week or more and up to 300 miles for it to be ready.

[1Coopgt]

Rock auto has the CC's for 263.xx ea side .

[Lil' Nasty]

Originally Posted by 1Coopgt

Rock auto has the CC's for 263.xx ea side .

This, just searched and found this too.

http://www.rockauto.com/en/catalog/c...converter,5808

[VTSummit]

readiness after a whole reset can take a while. Some states allow up to two "not ready" states in the ECU as long as no codes are present. Tuning out the CEL doesn't fool inspections, it just makes you feel better about your car not running properly.
Some drive cycles have very specific and bizarre criteria- google "gm readiness drive cycle" and you'll see several examples.
Seems as if someone would just look at your live data they could determine if you have a lazy or bad downstream o2 sensor. That's the ONLY way the ecu would get the idea you have a cat efficiency problem.