2002 S60 Rough idle but smooth at higher RPM

[draser]

Looking good, fuel trims in single digits show that everything up to the cat works as it should. I'd try to graph o2 sensors with scanner, see if you get waveforms like attached.

[quietcoolone]

Here are the O2 Sensor graphs while driving at hwy speed

[draser]

Not sure why you're getting the CL fault, it's as if ECU does not receive O2 info and reverts to map, so I'd check the coolant sensor and O2 sensors circuit to make sure connectors are clean and tight.

[quietcoolone]

Not sure why you're getting the CL fault, it's as if ECU does not receive O2 info and reverts to map, so I'd check the coolant sensor and O2 sensors circuit to make sure connectors are clean and tight.

I disconnected each individual O2 sensor and immediately got sensor codes.. and during that time there was no activity from the O2 sensors. The coolant sensor is working fine and the coolant is up to level.
I'm beginning to get a bit frustrated with this engine because it is doing unusual stuff.
at idle:
STFT 24.2
LTFT 1.6
LOAD 20.0
in Drive or Reverse
STFT -3.1
LTFT 3.9
LOAD 24.7
back in Park
STFT 17.2
LTFT 4.7
LOAD 27.1
while driving on the hwy, the engine runs strong and the fuel trims stay under 10% but ECM-4201 TWC efficiency Power deterioration code remains while Fuel System runs in CL-FAULT (close loop-fault) mode

I have run out of ideas here.. and really appreciate some directly related input.

[draser]

Just took a few readings on my car at idle, 2300 and 3000 rpm. Engine load stayed low at12-13%. My car's a turbo but I don't believe it'd be much diff than N/A. You may have a clogged cat based on your load readings. I attached the screen shots.

[quietcoolone]

Thanks draser.. you seem to be the only one willing to help and that is much appreciated.
If the cat is clogged, do you know of any remedies other than replacement?

[draser]

Not sure if cat is on flanges and easily to remove to confirm.

[quietcoolone]

Not sure if cat is on flanges and easily to remove to confirm.

An observation then a quick follow up question:
With a clogged CAT, my guess is that the engine would perform poorly at all times.
If i did not own a scanner or VIDA i would not be able to tell the High FT after initial startup (idle) because the engine runs normal and sounds normal (no hesitation, rough idle or hunting for idle). The only thing i notice is thin white smoke and water on the floor.
On the scanner engine starts in OL, then CL, then quickly to CL-Fault. (the only fault code is ECM-4201)
As stated before fuel trims at idle are high and remain that way until i either drive the car or rev the engine at which point fuel trims slowly creep down to normal and remain that way while idling (or driving)
So it appears that after initial start if i OT for a few seconds and release, FT normalize, if i just let it idle, FT go positive (especially STFT) and remain that way no matter how long it idles.
as if it needs an initial blow out or increase in air pressure somewhere in order for the computer to stop adding fuel, but even after FT normalize the engine does not switch from CL-FAULT to CL (no fault).
Any logical explanation to this dilemma?
I probable won't have time to remove cat until tomorrow.

Thanks again.

[mrscullini]

when i had a cat fail (on a suby), it didn't like higher revs, it bogged and sputtered. kinda opposite of your situation.

briefly scanning the thread, i didn't see any compression numbers. forgive me if i overlooked it. have you done a compression check? when i lost a valve on my '00 v70xc, it ran rough at idle but i didn't notice it at higher revs. you mention "thin white smoke and water on the floor", have you consider a shot head gasket?

[quietcoolone]

when i had a cat fail (on a suby), it didn't like higher revs, it bogged and sputtered. kinda opposite of your situation.

briefly scanning the thread, i didn't see any compression numbers. forgive me if i overlooked it. have you done a compression check? when i lost a valve on my '00 v70xc, it ran rough at idle but i didn't notice it at higher revs. you mention "thin white smoke and water on the floor", have you consider a shot head gasket?

Thanks for chiming in:
I was contemplating a compression test yesterday but then realize my gauge only reaches 100psi. I have a 300 psi gauge on order and will test as soon as it comes in.
When i first bought this car it had a idle rough,misfire and hunt for idle. I've since installed new plugs and cleaned the PCV, and replaced the ETM and those things took care of those issues. I no longer get misfire codes or hunt for idle, but positive fuel trims on startup and normal fuel trims after OT or under load.
There is thin white smoke from exahust (not sure if this is due to cold weather) but it subsides as the car warms up. The water drips on the floor are not substantial but may not be enough evidence for head gasket condition