How to tell if cats are bad?
Thread Starter
Staging Lane
Joined: Nov 2002
Posts: 88
Likes: 0
From: Odessa, TX
How to tell if cats are bad? What is an easy way to tell if the cats are messed up? My friend has slp lt headers and cats. His car is running like complete crap and we have tried changing the o2 sensors, we later put o2 simms in the back and it still is running like crap. Autotap said the 02 sensors were messed up, but we can't figure it out what else could be wrong. My only guess is maybe the cats. Any help would be appreciated.
Re: How to tell if cats are bad? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Roarin_8:
<strong> Well one way to tell would be if you smell a rotten egg smell. That would indicate a bad cat. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That is a hot overloaded (with fuel) catalytic converter. It is normal for them to smell when you beat on your car. What exact codes is it setting? Are the o2 harness extentions ok ,not melted? The pcm determains the catalist's efficency by looking at pre-cat o2 voltage (sensor1) & then looks at post cat. o2 voltage(sensor2) If the sensors #1&2 do exactly the same thing (go rich/lean in unison) it assumes the catalyst is not operating. A good cat. produces oxygen & co2 so sensor #2 tend to be on the leaner side than pre-cat sensors.
<strong> Well one way to tell would be if you smell a rotten egg smell. That would indicate a bad cat. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That is a hot overloaded (with fuel) catalytic converter. It is normal for them to smell when you beat on your car. What exact codes is it setting? Are the o2 harness extentions ok ,not melted? The pcm determains the catalist's efficency by looking at pre-cat o2 voltage (sensor1) & then looks at post cat. o2 voltage(sensor2) If the sensors #1&2 do exactly the same thing (go rich/lean in unison) it assumes the catalyst is not operating. A good cat. produces oxygen & co2 so sensor #2 tend to be on the leaner side than pre-cat sensors.
Thread Starter
Staging Lane
Joined: Nov 2002
Posts: 88
Likes: 0
From: Odessa, TX
Re: How to tell if cats are bad? The codes it was getting before the new simms and new oxygen sensors were put on are as follows: P0140, P0160, P0153. I will check for any melting of wires I didn't even think to do that, I'll autotap tomorrow and see what the codes are too.
