Catalyst test in AutoTap?
05-21-2004, 04:42 PM
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Catalyst test in AutoTap? Can someone please give me some info on the catalyst test that can be performed in AuotTap. What I need to know is what it tests and why.
To give you a brief history on my situation and why I am asking the question read on. I went for a sniffer emissions test last month and failed miserably. I ahd the opportunity to get some logging on AutoTap last night and everything looked good. My LTFT and STFT's were good, )2's read okay, I had no KR and I was running about 40 degrees of advance.
When the tests were performed everthing came back passed except for the catalyst test, it said it could not be performed. So know what I need to know is how to proceed in diagnosing what my problem might be.
My car is relatively stock, but I do have Mac headers w catted y-pipe a MagnaFlow cat-back and a DirectFlo lid for engine mods.
At this point I suspect that my Mac cats are no good even though they are less than a year old but any suggestions at this point are greatly appreciated.
Thanks for reading,
Brett
To give you a brief history on my situation and why I am asking the question read on. I went for a sniffer emissions test last month and failed miserably. I ahd the opportunity to get some logging on AutoTap last night and everything looked good. My LTFT and STFT's were good, )2's read okay, I had no KR and I was running about 40 degrees of advance.
When the tests were performed everthing came back passed except for the catalyst test, it said it could not be performed. So know what I need to know is how to proceed in diagnosing what my problem might be.
My car is relatively stock, but I do have Mac headers w catted y-pipe a MagnaFlow cat-back and a DirectFlo lid for engine mods.
At this point I suspect that my Mac cats are no good even though they are less than a year old but any suggestions at this point are greatly appreciated.
Thanks for reading,
Brett
05-21-2004, 05:42 PM
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what exactly failed? co hc nox?
probably just a bad tune. you can tweak out the most miserable cats to perform well.
ie too much timing can easily raise your noX way beyond reasonable amounts.
probably just a bad tune. you can tweak out the most miserable cats to perform well.
ie too much timing can easily raise your noX way beyond reasonable amounts.
05-21-2004, 08:03 PM
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I failed all 3 of the gases on the cruise test but passed everything on the curb idle.
Where I'm from there are 2 emissions tests performed as well as a visual, a gas cap pressure test and a few others I'm not sure of. The 2 emissions test consist of a test that measures gases at idle and one that is conducted at 40km/h. It was the 40km/h test I failed all the gases on.
Where I'm from there are 2 emissions tests performed as well as a visual, a gas cap pressure test and a few others I'm not sure of. The 2 emissions test consist of a test that measures gases at idle and one that is conducted at 40km/h. It was the 40km/h test I failed all the gases on.
05-21-2004, 09:38 PM
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hmm if the o2's are fine , then it sounds like bad cat(s) or not good cats. High HC is a good sign of a dead cat. High CO is tuning usually, and high NOX is a dying cat or running excessively lean/high timing.
You did warm up the cats a good bit before the test? yeah i'll assume that.
Normally i find when i back off timing, the noX drops, the other 3 remain similar.
sounds odd indeed. maybe the cats are dead or were not sufficiently heated. Your o2's are cycling in closed loop right? If you set a 14.7:1 open loop, the 3 way catalyst would do not much work as it requires the rich/lean sweeps to catalyst the bad stuff away.
You did warm up the cats a good bit before the test? yeah i'll assume that.
Normally i find when i back off timing, the noX drops, the other 3 remain similar.
sounds odd indeed. maybe the cats are dead or were not sufficiently heated. Your o2's are cycling in closed loop right? If you set a 14.7:1 open loop, the 3 way catalyst would do not much work as it requires the rich/lean sweeps to catalyst the bad stuff away.