Code Confusion - Need Advice

[Fly N Drive]

Hello All-

I have been throwing a CEL for about the last 9 months. Its the dreaded EA and E9 'Catalyst Efficiency' codes. I usually reset it and it takes about 3 months go come back on but its now coming on more quickly. It only comes on when I'm going over 60mph on a longer haul trip. I've heard some people think it could be an after cat O2 sensor, some say a before cat O2 sensor...I say its the cats.

My only confusion is that I started getting both banks thrown at the same time. What are the chances of both sides going out at the same time?

Anyway, I think its time for me to change my cats. I've done a search and don't see many suggestions for an OBD II car. I'm a big stock setup guy but would go with an aftermarket converter if it would give me better flow and save me some money.

If you have suggestions of links to other sites that would help. I'm pretty handy with a wrench but not so sure about a welder.

I run 91 fuel for anyone who cares. I've heard that that can sometimes give an excessivly rich mixture. Not sure what to think about that.

Thanks guys

[amancuso]

I was getting similar codes, my problem turned out to be a bad/intermittant MAF sensor as well as a torn boot from said sensor to throttle body. I suppose the values that pass thru there show up as a fault near the cats.

-Al.

[Fly N Drive]

So you were getting both those codes and when you changed the MAF sensor they stopped coming back? I'll have to check that out, I bet its a lot cheaper.

[Fly N Drive]

BUMP - Because I'm still confused

[Zaks]

BUMP - Because I'm still confused

i think it's either your sensors (post cat) or your cat, or both. i got a check engine light, replaced my cats, got another one like 6 months later, it was one of the o2 sensors, so i replaced both, and now everything is fine.
installation of o2 sensors is very simple if you can lift the car up (i suggest lifting it on the pass. side but others may have other opinions. you just disconnect the old sensors ( you will see a black cover that protects the wires and leads towards the engine to the connectores. after you disconnect them, unbolt it (17mm or 19 mm or somethign else in that area, sorry i forgot). bolt in new ones and connect and you're done.
when i changed my cats though, i needed an extension with a "swiveling" head because a couple of the bolts that connect the cats to the headers could not be reached with a straigh extension.
it would be ideal of course, to replace everything, put the sensors in while the new mid section is off the car, then just bolt in the mid section.
hope this helps

[stuvx]

If you have access to a scope (digital or analog), you can compare the waveforms for the pre- and post-cat O2 sensors. The post-cat sensor should be pretty stable in the upper end of the voltage range (~700-800mV).

Find a mechanic with a 4-gas analyzer and you can test the cats. There is test procedure taught to all California smog techs. I can scan a copy of the procedure to give your tech if you want.

If you just want to get rid of the CEL without fixing the problem, you can always use O2 simulators for the post-cat sensors.

[Fly N Drive]

That sort of helps, thanks a lot for your reply. I'm also kind of trying to get a feel for what my options are as far as new cats go. I know with OBD I cars you can get the highflow and weld them in, I've heard otherwise with the OBD II. Any suggestions on what to do if I have to get new cats?

[Zaks]

That sort of helps, thanks a lot for your reply. I'm also kind of trying to get a feel for what my options are as far as new cats go. I know with OBD I cars you can get the highflow and weld them in, I've heard otherwise with the OBD II. Any suggestions on what to do if I have to get new cats?

well like i said, i replaced mine with non OE ones.. they don't have the silencers (i think that's what it is) after the cats but they have worked fine and i didn't notice them being louder. i don't know what you can do as far as aftermarket performace cats go though.

[Fly N Drive]

If you have access to a scope (digital or analog), you can compare the waveforms for the pre- and post-cat O2 sensors. The post-cat sensor should be pretty stable in the upper end of the voltage range (~700-800mV).

Find a mechanic with a 4-gas analyzer and you can test the cats. There is test procedure taught to all California smog techs. I can scan a copy of the procedure to give your tech if you want.

If you just want to get rid of the CEL without fixing the problem, you can always use O2 simulators for the post-cat sensors.

Hey Stuvx-

I'll take a copy of that procedure if you can. I wouldn't mind having them tested because it may save some mula. It looks like you can attach other files on the forum?

[stuvx]

Fly N Drive, check your PM.

[Zaks]

Fly N Drive, check your PM.

would you mind PMing me that also?