02 Sensor? Fuel Filter? (vida dice data included)

carboncow · Post by **carboncow** » 06 Oct 2011, 21:08

2001 V70 T5 about 160K miles. No history known on fuel filter or O2 sensors from previous owners.

Wife said this week the car just died while driving about 45MPH down the road. Restarted again w/o any more issues. I witnessed this same issue about a year ago and never could reproduce.

Newer volvo plugs. Newer MAF

Ran the Vida Dice and came up with the following new error codes (see attachments)

ECM-261A Long-term fuel trim, bank 1 - Upper Limit
ECM-4801 Three-way catalytic Converter (TWC) efficiency, bank 1 -

(ignore other items listed in screenshot)

I've also included the Vida discussion on posible causes, as you can see they run the gamut. From my experience I'm think the 02 sensor and/or fuel filter could be to blame with most likely the 02. We feel the car idles a bit rough and has sluggish moments.

The only other thought I have is an air leak as I had the intercooler pipe off at the turbo about 3 weeks ago trying to clean up a posible oil leak in the area.

What do you think?

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EDIT: I added in the snapshot values showing the upper value for bank 1. Maybe you can explain what these are telling me.

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Post by **jimmy57** » 06 Oct 2011, 21:53

Let's not guess, let's test.
First, the coolant temp is low. Was the car driven a short distance when this happened?

Oxygen sensors can be tested easily. Drive car 10 minutes to assure fully warm engine and fully operational temps sensors.
Load bank 1 front and rear sensors and click on "Enlarge" to show the loaded values so you can easily see them.
there is a vac hose on that car on driver's end of intake facing the head. With engine idling pull that hose off and watch the sensor values. THe front sensor should go to 1.25 or higher in 3 seconds while the rear should drop to .1 V or lower in the same time. Leave hose off for 3 minutes so the ECM adjusts fuel trim to comp for the leak. Now plug the hose on and watch the values again. Front should drop below 1.00, probably to .85 +/- within 3 seconds while the rear should go up to .75V or a little more.
The hose being removed causes lean and once the fuel trim has compensated then plugging the hose back on nipple will make it rich. Good sensors will have quick response to the right values. If it passes this then MAF becomes suspect but intercooler hose and tubing leaks need to be ruled out as well as MAF to turbo hose cracks.

carboncow · Post by **carboncow** » 06 Oct 2011, 22:00

Thanks Jimmy.

Will test out tomorrow.

What is bank 1 vs. bank 2, I was curious to this reference?

EDIT: OK, I"m going to guess bank "2" would be a V6 or V8 in the XC90?

Note, I put in an aftermarket MAF (got cheap) about two months ago (kept the old one). So if the 02 check out maybe my suspect cheapo MAF.

When I check the air intakes is there a good test if nothing is glaring? I know I've read old timers spraying different things in the area to see if the car revs to find intake leaks. Does anything apply if I don't find/see a definite leak?

draser · Post by **draser** » 08 Oct 2011, 09:45

The O2 signal should rapidly fluctuate up/down (at least once per second), between 0.1-0.9 V, with the DC component centered around 0.45VDC. Vida should show that. Engine at operating temp, idle. If fluctuates slower, or it's stuck low/high the sensor is bad.
You already have the mass air flow, you need the map to see if correct for corresponding rpm. You can test intake vaccum using one of those small vaccum pumps, or a gage, T-ed into intake. That should give you a pretty good idea of what's going on.

carboncow · Post by **carboncow** » 08 Oct 2011, 10:26

Very helpful on the 02 sensor. Will be checking out in detail this evening and reporting back. Just priced the 02 for the car, rather impressive cost compared to other euro vehicles I've owned. Anyone ever point in a generic Bosch at a fraction of the cost and just wire in the old connection? (done this on many Vw)

Are you stating to check for intake leaks with a vacuum gauge while running? Any idea what values one would even be looking for?

Post by **JDS60R** » 08 Oct 2011, 10:54

Purchasing the 02 sensor through Matt's link to Amazon yields prices so low on direct fit Bosch that it rules out (at least for me)the generics and the problems many have had with them. See the Gold bar under "Volvo Formus" (above) for the link.

carboncow · Post by **carboncow** » 08 Oct 2011, 11:00

Thanks, I'm on the amazon page but 10,001 02 sensors come up and the Volvo number doesn't seem to apply here. I only seem to find the universal types.

Are you referring to the Amazon link then?
If so do you have a clue what Bosch number applies?
So you have seen disscussion on the boards about universals being problematic at times?

draser · Post by **draser** » 08 Oct 2011, 13:13

Intake vaccum leaks - A steady reading in the range 17-21 in-Hg is considered correct, anything steady around 5 is air leaks. Engine at temperature and idling.

carboncow · Post by **carboncow** » 09 Oct 2011, 19:07

OK, guys I need more input.

I can tell you I don't feel good about any of the testing I did based on your comments as I didn't see the expected values.

1. Jimmy: I pulled off to intake hoses (together and seperate) and got no change in values, idle or behavior of the car. See the screenshot I included of the only hoses I could determine where on the intake facing the head. I know these hoses well as I had the intake out cleaning that PTC valve last month. Am I in the wrong area?

Values for 02 Front Bank 1 stayed right around .99-1.00 the entire time the car was idling (at temp). Even knowing the AC was kicking on changing load and the car idle would change and stuggle at times these values didn't seem to change.

Values for 02 Rear Bank 1 between .60-.66v no matter what too.

2. Draser: I'm not really sure where to get these values you mentioned as they are different then what Jimmy was talking about. Which 02 are you stating should flux (front or rear) between .1-.9v front or rear? Am I reading the wrong datapoint? What is the unit of value for 02 front as there is no "v" or anything. If you are stating DC component of .45v for the rear then I'm obviously high at .64-.66v

There is a MAF value is this of use in this diagnosis or is the value a funtion of RPM as Draser mentioned. At this time I have no gauge to test for air intake leaks. I checked all the intake and intercooler clamps and hoses and see or heard no leak. At the same time since I pulled off those two hoses it makes me think there in fact could be a leak as pulling the hoses has no effect.

Do the values for Air mass correction factor mean anything?

MAF values were between 13-17 kg/h how do I convert these to in/Hg mentioned by draser or did you mean kg/h. I have a few conversion calculators but they do not mention "inches".

What does all this data tell you guys?
or am I no where near getting to the bottom of this?

EDIT: I'm half tempted to put the old MAF back in to see if anything improves. The car is a bit of a idle'ing mess as the AC comes in and out. It does far better w/o the load of the compressor. I cleared all codes drove again today and still got the error pertaining to Long-term fuel trim upper.

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draser · Post by **draser** » 10 Oct 2011, 08:54

Sure looks like it's open loop on O2 values. The sensors are not hot enough, rev up several time after full warm up. Pre-cat sensor will fluctuate 0.1-0.9V, post-cat will stay pretty steady at around 0.5V.