TangoVTEC

Right, amidst fitting my audio gear I had the battery disconnected for a couple of days.

Upon re-connecting I was treated to one of the lumpiest cold starts in history (I know its very cold out) and a bright shiny CEL light on the dash, along with some rough running for good measure.

I took the car for a short spin around the block and found that whilst it pulls ok under acceleration it is very jerky under light throttle, and cant seem to idle smoothly, sometimes holding at 2000rpm, sometimes dipping and rising around 1000rpm.

I get back, disconnect postive again for about half a minute, and voila; no cel and smooth idling.

Happy with myself I make a brew and bask in my magnificence......

Or so I thought!

I did a hundred mile or so round trip today, and on the motorways the car behaved itself well, however towards the end of the journey (in traffic no less) I got the same jerky throttle and unwillingness to idle smoothly, albeit with no CEL this time. The car was left to cool fully, and when I came to make another journey this evening the jerkiness was worse than ever (when stone cold) and then guess what; CEL returns.

I bridged the service connector thing and retrieved code 6-7; which according to modifry's page means 'Catalyst system efficiency below threshold'.

Does this mean the cat is FUBAR?

More suspicious/worrying however is why this would have happened after the car was sitting dormant for 2 days (with the battery disconnected). It was perfectly fine before.

I am now very worried I may have damaged some wiring in either footwell kick panels when I was working in there running new speaker cable.

Long shot; but would anyone happen to know if the cat sensor wire travels through either of these areas?

Otherwise, I will have to check all the wires in all the plugs one by one....

Could my cat converter have just died?

m1bjr

I would suggest that yes the cable would route that way - ECU is on the passenger footwell under that kick cover.
This of course being the second sensor thats in the cat and the cable appears to go through the tunnel somewhere.

Removing power to the ECU for a long period does in effect reset its trim values etc.
After reconnection it should quickly re-learn to idle smoothly.
It sounds as if yours isnt.
You need to get the engine up to FULL operating temperature for a short while to achieve this.
They do say to wait for at least two radiator cooling fan cyles and it should suffice.
Cat efficiency CEL may be a result of idling long periods with this highly rich mixture and I have had this even with a cat on once, as have others.
So, I think more likely it's a cascade error from not having re learned the idle properly.

Hard to get up to temp by driving in this weather though isn't it!
Unlikely to be a cat itself from experience they break up but still operate (but noisily).
Worst case is probably a damaged secondary O2 sensor at the cat, or as you suggest a connection somewhere.

TangoVTEC

Thanks, very helpful!

As you have said, after I disconnected and reconnected the battery the car idled perfectly.

I think I will try that again, but let it warm up and idle for two fan cycles as suggested, whilst checking for obvious broken wires etc.

Unless anyone else has any suggestions?

Merry christmas all!

m1bjr

Any time... go safe.

Merry Christmas to you too.

Steve.