94 1.5l D15B7 Civic

So I just changed my o2 in hopes of passing emissions testing.

Since the change the car has been running like crap. Bogging down in lower RPM's until 2500 or so when it takes off.

It's actually acting like the timing is off, but I just checked valve and spark time. It's fine.

Does the ECU need to be reset or is there a learning period after changing the o2?

 

yea pull main ecu fuse and (+) term for 30 sec main fuse is under hood should be back left corner 15a

 

yes reset the ecu for atleast ten seconds.

 

If you bought a Bosch O2 sensor then that is your problem (they're crap).
The OEM for Honda's O2 sensors is NTK (NGK) and they are usually under $60 shipped

 

Will try resetting the ecu and will report back.

Is pulling the fuse sufficient, or does the battery really need to be disconnected to reset the ecu (and my head unit :D )

TheKGB3,
Nope I go to lengths to stay away from Bosch products. (Been burnt by faulty o2, plugs, and fuel pumps)

 

I thought Denso made the OE 02 sensors?


.

 

Nope, NTK is the O2 sensor division for NGK, and they are the OEM supplier to Honda for O2 sensors.

 

I have a bosoch o2 and its fine, so i would call them junk unless you have proof.

 

Well just to update..

I've put about 200 miles on it since resetting the ECU.

It does run a little bit better. BUT. My last fillup I only got 25mpg. Mostly highway.

Could a new o2 be that bad, but still not throw a code?

 

^^Thats about whay i get, although i got 28 last tank and 25 this one.

 

FWIW, I was getting 32-38 before the new o2. (Threads are ruined on the old one so no I can't put it back in.) :/

 

Hmm well maybe thats your issue, the only thing that changed with mine was the octain #.
93 on the 28 and 87 for 25, both were from shell.