Check me on something - rough idle, code 26 (1 Viewer)

[41magsnub]

94 80 series, total battery failure and it sat with battery installed for several weeks while I was out of town. Changed out the battery, it idled rough as hell for a few starts while the ECU figured things out again, then settled down and ran normally. By rough I mean it was killing itself on the RPM drops initially.

Later in the day driving around town the CEL comes on for a few minutes then goes off. Then it came on again and stayed on. I pulled the code which was 26 for rich fuel mixture. Researched it and one of the causes of that is rough idle. Poked around the O2 sensors anyway, but didn't take anything apart. The only thing I fixed was I noticed one of the shrouds around the CAT intake by that O2 sensor had a broken clamp and was rattling like crazy. Replaced it with a hose clamp.

Disconnected the battery again to reset the ECU, hook it back up but this time did not let it idle low and rough. I kept a little gas the entire time for 5 stop and start cycles. Commuted in it for a week and so far no CEL.

Think the loose clamp/shroud were messing with the 02 sensor, or maybe the really crappy idle and engine killing caused the code 26 when nothing was wrong after the ECU finished learning?

 

[baldilocks]

I think the dead battery and resulting poor idle you experienced for a bit set the code. As you stated, all has been well for a week. You can't fix what ain't broke but over thinking this machine can surely break what was not broke yesterday. Ask me how I know!

 

[LS1FJ40]

I've heard it can take 4-5, 15 minute drives for the ECU to figure things out. This likely caused the rich fuel syndrome and set off your CEL. If no more CEL, quick thinking and drive it. I doubt the Cat guard caused a CEL. I could be wrong but mine had been loose for a year or so without setting a CEL.