04 TJ - Could it be my oxygen sensor???

[crusty]

Hi all.
My 2004 TJ 4 litre has an issue which appears on colder days, winter, spring and fall. No problem in the summer. What happens is that when shifting from 1 to 2 and 2 to 3 the engine is slow to drop rpm's. Sometimes the rpm's even increase upon depressing the clutch when shifting. After a few minutes of driving it's OK.
Here's what I've done so far:
- checked circuitry on the TPS
- checked for vacuum leaks
- cleaned the IAC motor
- checked throttle linkage, springs, gas pedal cable
Here's some codes I've gotten:
P0455 and P0442 - EVAP emission control leaks large and small. I think this was from my aftermarket locking gas cap which I was over tightening.
P0135 - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1) I've had this code on 3 separate occasions.
I'm thinking of putting in the new 02 sensor but is there anything else that anyone can think of that may solve this rpm problem when the engine is cold? Is there some way to check the 02 sensor or circuitry?
Any advice would be appreciated. Thanks to all.
Cheers, Crusty

[specialk]

Sounds familiar.  I had a similar issue.... was throwning evap codes, increase in revs...   ended up changing the TPS and it solved my issues

[birdo]

Could be O2.........any smells especially a sulphur or rich mixture? Does it hesitate and buck at all? Good some days and terrible the next?
Is your fuel economy in the toilet? You could try disconnecting the electrics to the O2 sensors and see if there is any difference. If you are up to
80,000 kms or more, they are probably due for a change anyway. Easy DIY...just soak them good with DW-40 the night before, 22 or 24mm wrench if I remember.
Get OEMs for replacement.....maybe avoid the aftermarket ones....especially the El Cheapo brands.

Changing out the O2 in my rig made a huge difference.

[vantagetes]

22mm for the oxygen sensors however I would lean towards TPS or IAC.

[TJ 127]

Any luck solving this? I hav same type of issues with my  01 Tj
-Cheers