jonpauls

Recently did some work which involved removing plugs, wires, headers, and o2 sensors on my C5 and now the car idles and runs fine for ~60 seconds before going off-scale rich (and un-drivable) according to my wideband. What would cause a delayed affect like this? I already double checked each connection.

pantera_efi

iTrader: (1)

Hi, one common EGO/UEGO problem, for the sensor, IS this item is constructed with the same material as a Spark Plug.

Thus it can be "fowled"

The output, when Rich a high Voltage, when Lean a LOW voltage output.
When "dead" or Fowled the same, no voltage.

This can cause the EMS to provide EXTRA Fuel.

Your question is not clear, could this be your case ?

Lance

jonpauls

Lance, the UEGO is solely hooked up for monitoring and I'm confident that it's correct. The end game is where to look to get the car running again given the symptoms. Symptoms being that the car runs fine for about a minute but then loses all power and is pretty much undrivable. I realize a bad O2 could cause a rich AFR, but could a bad O2 sensor have a delayed effect like this?

LeftySS

iTrader: (17)

On start up the car runs in open loop (no o2 feedback) which is why it runs ok, then after a certain amoung of time depending on engine temp, will switch to closed loop (feed back from o2 sensors) which if bad could be causing your issue. When the o2s were removed they couldve been damaged i guess. If you have double checked all the connections and made sure a wire hasnt been burned or cut, try some new o2s and see if it fixs the problem. What kind of work was done? Any other wiring tampered with?

jonpauls

I was thinking that was the case, that makes perfect sense. I'll take a closer look at the o2s. As far as what was done, I was pulling the drivetrain on my C5, so the only electrical components that could be affected are plugs, wires, the o2s, and possibly the map sensor if I bumped it. Thanks!

HappySalesman

iTrader: (3)

When I had an exhaust leak in my camaro a few years ago, it ran like crap after I got it back from the welding shop. Turns out they didn't remove the o2 sensor when they did the welding and fried it.

car would run great for about 2 minutes, then start pissing fuel down the tailpipe. Swapped o2 and it ran fine.

RevGTO

iTrader: (12)

Answers are on the right track here. An O2 harness lying on a header and shorting will cause the car to run fine in open loop and then go haywire once closed loop kicks in. Ask me how I know.