Where to go from here?

[blowby]

Reoccuring CEL 172/173 HEGO RH Lean/Rich...

The Engine ran terribly a while ago and I was getting these codes as well, so i replaced the front O2 (bosch unit) and cleared the codes and the noticeable problems went away.

However soon after I did this the CEL comes on, only after the egine is good and warm. It will go on and off periodically, but the car seems to run fine.
Mileage seems to be a bit down from where it was before all this started (1 yr ago).

Any ideas what to check from here?


thx.

Bryan

 

[Off Road SHO]

So what are your codes now that the CEL has come on after the first clearing?

Tom

 

[blowby]

The same....172/173.

Bryan

 

[Off Road SHO]

What are the definitions of those codes?

Tom

 

[blowby]

172 HEGO sensor indicates system lean (RH).

173 HEGO sensor indicates system rich (RH).

 

[Off Road SHO]

Sounds like you have a vacuum leak.

Tom

 

[blowby]

I considered that, and I sprayed down all the vacume lines etc that I could find with ether, no change in RPM.

Also, why would this only affect the front bank?
Wouldn't a vacume leak affect the entire intake system?
Also, why does this only show up once the engine is fully warmed?

Bryan

 

[ohfosho]

the ecu only uses data transmitted to it from the O2 sensors once the engine is at operating temp... it has basic settings stored in memory to use until that time.


guess what, you seem to have replaced the wrong sensor. the codes are for the right or rear according to sho pheonix project. normally you should replace both as a set anyway while you are there...
http://www.shophoenixproject.com/eec/code3.htm

 

[blowby]

Uh,0h....
my bad....
that is the side I replaced....

Anyone ever hear of this issue happening due to a plugged up CAT?

Bryan

 

[e_clouser]

In my experience, a plugged cat would **** performance. I could be wrong

 

[blowby]

I don't push it too hard anymore, I've got 200k on her and at that age it just doesn't make sense to try to get max performance until I can afford some potentially serious replacement parts....lol.

But that being said, the performance has not noticeable decreased over the last year or two....I may put a pressure guage on the O2 port and check my back pressure anyway.

I'll keep you all posted.

Bryan