DTC - TWC system low efficiency .... ?

[MidLifeSpeed]

Within the last two days I keep getting this code. The acronym is "three-way catalyst" system low efficiency. I'm guessing this means that the converter is not very efficient at removing all of the "pollutants" from the exhaust.

What are the conditions that set this code? High O2's on the after-cat sensor ?

Can the converter (which has been on less than 1 year) be damaged by an excessively rich exhaust ?

Last week I was driving home from work (50+ miles) and the car lurched, then started missing real bad. I figured I had a wire or coilpak problem. Got it home and sure enough, had no fire from the rear-most coilpak. Bought an OEM replacement for the Accel (temporary), but it didn't fix the problem. Wound up having to replace the electronic ignition control module ($175 at O'Reilly's, $275 at dealer). That fixed my problem but in the meantime I had driven probably 100+ miles on 4 cylinders (runs like crap ... believe me).

Could the excessively rich exhaust during those 100+ miles have killed my converter ?

[DominusEtDeusNatus]

I got the low efficiency code and then started getting misfire codes. I should get to the bottom of my problems this week.

[wolf]

I know this is off-subject but <blockquote>quote:</font><hr>coilpak problem.... . Bought an OEM replacement for the Accel (temporary), but it didn't fix the problem. <hr></blockquote>- I have heard nothing but complaints about the accel coilpacks.....
<blockquote>quote:</font><hr> I had driven probably 100+ miles on 4 cylinders (runs like crap ... believe me). <hr></blockquote>- try to drive a v8 only runnin on four cyl{thats what happened to me in my nova)

[Magnus]

3" hi-flow cat won't filter as much as a stock cat would. The PCM sees this and sets a DTC.

I corrected the problem by putting an O2 Simm after the cat. I got my 1 o2 sim from caspers electronics here in IL.

[MidLifeSpeed]

Thanks Keith,

The only caveat is that the converter has been running since last Feb without setting a code.

Do you think my last week's "fun" with 100+ miles on 4 cylinders could have "contaminated" the hi-flow cat while running so rich ?

The only other recent change is different exhaust tips on the car. I removed the "redneck" tips (9" long, 3" diameter round flare tips) and replaced them with Z-28 style tips.

[strange_trp]

super rich can damage converter... i'd really have to see post-cat O2 response on scan tool to really be able to tell.

[MidLifeSpeed]

What operating conditions do you want to see for the logged O2 data from the after-cat sensor ? Idle? WOT ?

I will be able to log the data, as soon as my laptop battery recovers :rolleyes:

[strange_trp]

pre and post cat O2 would be fine, make sure you're in closed loop. other stuff like long term and short term trim and other sensor stuff would be good too. not jsut a snapshot, but changes over time would be most helpful. pre-cat o2 response should vary rapidly in closed-loop between .1v and .9v. short term trim should mimic these oscillations, going from negative to positive regularly. the post-cat sensor should remain much closer to .450v and should not fluctuate nearly as widely or as frequently...

didnt get the attachment with the email... resend???

[MidLifeSpeed]

Thanks for the info strange ....

I cleared the code last nite, and took it through 4 drive cycles without the code reappearing.

Sorry about the attachment not coming thru ... has something to do with Microsoft Outlook 98 and the rich text formatting ... happens to me with attachments all the time. Turns out I didn't have all the data I wanted to send anyway. :rolleyes: