Ahsai

No worries about it. "Fail" actually means "Not ready" which means the conditions of which to run the O2 sensors have not been met yet. Once met and tested, it should say "Pass" if the sensors are good. Don't ask me what if the sensors indeed fail since I don't know

So just drive your car more and recheck later.

sandersd

The sensors fail or are not ready after startup and after driving for 20 minutes. I'm curious what conditions must be met and tested, if their status is the result of disconnecting the battery, and if the rough feel of the engine is somehow related and will clear up once I've driven enough for the relearning process to finish.

I'm reading another thread: changed-cats-but-still-getting-po430.html that has a wealth of info on cats and o2 sensors but I haven't finished going through it yet.

Perhaps these questions are answered there.

sandersd

I just had a thought: the gas in my tank is over a year old. Tonight I'll add a dose of injector cleaner and refill with fresh gas and see if that makes a difference. I suppose I should drain the old but what would I do with it?

sandersd

Attached is a small portion of the readings from the Durametric. The full file has 450 separate samples - I've selected 33 that show the range of values for the pre and post cat O2 sensor voltages. Each individual line shown actually repeated for 10 to 20 samples - it varies - but that can be seen in the full file available in a post above.


Notice how in the last half of the readings the voltage of the pre cat sensor varied wildly.

Ahsai

O2 sensor tests should not be too difficult to set (e.g., compare with Evap test). Normally, O2 test will complete in a 20 min drive for me. Maybe you can drive the car for another 20min or so with some local and highway speeds. Regardless, if the DME really thinks your O2 sensor(s) have failed, it WILL trip the CEL and give you those O2 sensor related codes.

Some generic OBDII reader can retrieve exactly which test(s) failed using mode 5 or mode 6 (there are multiple tests to test the voltage swing, response time, voltage range, etc.).

Battery disconnect and DTC reset will clear all readiness codes, which will become ready one by one as you drive the car more.

One year old gas is definitely stale!

Ahsai

The swing is normal and expected. You have a problem if the precat sensor voltage does not swing.

Everything after 35:25.691s looks fine (precat swings about once per second) and post-cat is close to 0.6v steady. I don't understand those "128" and smiilar values though since O2 sensor voltage should be between 0.0v and 1.0v. BTW, at cold start before the O2 sensors get up to their operating temp, the reading should be 0.45v, which is a biased voltage supplied by the DME.

sandersd

Ahsai, thanks for the read! I'll fill up and drive it more this evening,

alpine003

Does this mean you've been repairing this for a year?

sandersd

No, it means it's been sitting for a year. The clutch went out in Dec of '12 so I parked it till I could afford the parts (2 kids in college). Removed transmission in April or May for inspection and found my IMS was leaking oil, RMS was dry. Ordered parts and tools in August and started working on it weekends as parts came in but, as this is my first foray into Porsche maintenance, it seems I was always finding some other part or tool I needed to perform some task that I didn't have, so I'd have to order it and wait. Then there were many weekends I couldn't do anything either due to weather, travel, or illness, plus I did everything by myself.

Speaking of illness I was driving my other vehicle, a 2000 F150 4x4, to work one morning and kept hearing a squeaking noise from the engine. As I exited the tollway I heard it again and it sounded like a kitten. When I arrived at the parking garage I popped the hood and found a five week old calico kitten behind the fusebox. As I pulled it out it scratched my pinky, not bad, but it did break the skin and bleed a little. I took it back home to drop it off and washed my hand but apparently it was too late - three weeks later I came down with cat scratch fever which is a real disease caused by a bacteria. Let me tell you the flu is a cakewalk compared to this. I would go to bed with a fever, shivering so hard I could barely breathe and wake up soaking wet from sweat for three days. One week later it happened again and I went to the doc for antibiotics after the lymph node in my elbow swelled up like a walnut, red and burning. It came back one more time a week later but much less debilitating.

Anyway, then my son graduated from college so I had to go to that, Thanksgiving, Christmas, etc. Now that I've done it and have all the requisite tools I could probably do it by myself in a three day weekend without breaking a sweat, not that I'd want to.

So, no I haven't been repairing it for a year but it's taken me this long to put it back in service.

KrazyK

Holy S#$%! Man you have had a really tough year. Hope this year is much better for you.

What works for me is, whenever I start thinking "wow, this day,week, month, etc, couldnt get any worse, I remember our fallen and maimed, brave service men and women, then realize I dont have it so bad after all!

sandersd

Thanks, I appreciate that.

sandersd

Drove to the gas station with the Durametric hooked up and took a bunch of readings on the way there and different readings on the way back. When I returned I checked the ready status and all were pass except now the cat fails. I checked the after cat temps and they were around 500 C so I think that's OK.

Ideas? Observations? Comments?

sandersd

BTW here are some of the values after warm up:

RPM = 700
Mass air flow (HFM) = 16
Supply voltage 13.48
Hot film MAF = 1.25
Oxygen sensing bank 1 = .99

Have no idea what their significance is yet or what is the acceptable range, except for RPM of course...

Ahsai

Good news on the O2 sensors that they passed. Regarding the cats, add techron on a fresh tank of gas, run through the whole tank and then retest. There is a good chance this failure is due to the stake gas and engine inactivity in the past yr. It may go away once you drive the car more.

If not, 200 cell sport cats is always a great option for folks outside of CA and NY.

Ahsai

Btw, the warm up numbers look fine. For cat diagnostic, you need to log all 4 precat and postcat readings. Too early to look anyway...