Codes 176 & 177 AFTER 02 replacement?

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Huntervf

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I've had a CE for awhile now on the 93 ATX; light would usually come on after a couple WOT events and once it came on it would go on / off for the duration of the trip regardless of driving habits. Finally checked codes a couple weeks ago, 176 & 177... front 02 lean or not switching, front 02 rich or not switching. Sounds like a cut & dry problem.

Replaced the 02 sensor last week. Hit full throttle several times on the follow up test drive, no light. Problem solved.

Two days later, there's the damn light again after a stab of the gas to merge with traffic. And now it seems to come on without the need for a hard accel, only moderate gas is required to light it up. Once it lights it's the same behavior as before; sporatic on/off for the duration. A check of the codes today gave me the SAME 176 & 177, that's all.

Car seems to be running fine. Fuel mileage is approximately 26 highway which is spot on this car.

Anyone have thoughts on where this problem lies? Perhaps my front bank really is running both rich & lean :shrug:
 

SHOtimer

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I would be suspect of a vacuum leak, throwing the mixture off. Did you use Bosch or Motorcraft o2 sensors?

Doug
 

Huntervf

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Off Road SHO said:
Chris,

It actually told you the front bank, or did it say bank 2?

Tom

From the offsite link at SHOtimes:

176: M Oxygen sensor not switching - system is or was lean left or front HO2S
177: M Oxygen sensor not switching - system is or was rich left or front HO2S

I thought about a vaccum leak, but from where and why only the front bank? The only thing I can think of would be the intake manifold isn't seated properly on the front side. Admittedly I did have all kinds of **** getting that intake back down on the engine, but everything seemed well and tight, and the 02 code didn't come for a couple months after all the 60k work was done.

I'm using a Borg Warner 4 wire 02 sensor; basic brand from Parts Plus.
 

SHOtimer

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I know there have been several guys on the board that have had bad experiences with the Borq Warner ones (new ones), I would try the Bosch ones....

Doug
 

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