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Old 08-11-2022, 09:46 AM   #1
PaulBorsan
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Default O2 sensor delete

Hey!

I bought a 940 b230fb. It came without catalytic converter because it got stolen. The problem is that the O2 sensor its missing too because it was connected right to the cat.

The question is: is there a way to run without the O2 sensor, the lambda sond light is on and the car runs really bad.

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Old 08-11-2022, 09:49 AM   #2
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it is possible with a NLA ostrich or a disabling the lambda feedback with a custom chip but it would be cheaper/easier to have an exhaust shop just weld in a bung with a generic 3 wire sensor into the exhaust. It'll never run well over time/be adaptive to conditions otherwise.
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Old 08-11-2022, 10:40 AM   #3
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Yeah it seems like it'd be more work than just either getting a bung added, or just putting in a cat that has the bung already in place
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Old 08-11-2022, 11:16 AM   #4
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Quote:
Originally Posted by PaulBorsan View Post
is there a way to run without the O2 sensor, the lambda sond light is on and the car runs really bad.

really bad is pretty much the only way it will run with no O2
your going to have to replace that stuff
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Old 08-11-2022, 11:39 AM   #5
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You kinda need that
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Old 08-11-2022, 08:53 PM   #6
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Short answer: yes
Long answer: no
Or
Short answer: no
Long answer: yes
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Old 08-11-2022, 09:01 PM   #7
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Is this a European OBD2 car?
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Old 08-12-2022, 07:46 AM   #8
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I'm with the crowd; get a new cat with a bung and the sensor to go with it. Much less work for far better results.

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Is this a European OBD2 car?
Volvo 940 only got the OBD2 connector in 1996, beneath the surface it's still OBD1.
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Old 08-12-2022, 10:05 AM   #9
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I am not sure what that means. All cars got OBD2 connectors in '96. I am just wondering if the sensor inside the Cat is only for Car monitoring which is the main feature of the OBD2 system or is it for CO mixture adjustments.
Is there no O2 Sensor in the exhaust manifold?
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Old 08-12-2022, 12:54 PM   #10
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Location of the O2 sensor moved on later B230 engines from the manifold/downpipe area to the cat. As far as I know they never had dual O2 unless someone put a wideband gauge on later.
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Old 08-12-2022, 01:04 PM   #11
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OK, that explains it better. Thanks! OBD2 had to have dual O2's but we never got 96-later 940's in the US so we do not see that.
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Old 08-12-2022, 01:12 PM   #12
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Usually, you can buy a universal fit cat and have the bung for the O2 sensor added to it. Then have a competent exhaust shop install it. That can be a lot cheaper than buying a direct fit one. If you want the cheapest cat possible. I'd shop over in the US at places like Jegs or Summit Racing.
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Old 08-12-2022, 04:30 PM   #13
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Originally Posted by PCH View Post
I am not sure what that means. All cars got OBD2 connectors in '96. I am just wondering if the sensor inside the Cat is only for Car monitoring which is the main feature of the OBD2 system or is it for CO mixture adjustments.
Is there no O2 Sensor in the exhaust manifold?
OBD2 became mandatory in Europe in 1998. There were no 940s with OBD2 monitoring; the OBD2 connector seen in 96-98 euro models was simply wired to OBD1 circuitry. Here's a code reader I made for my 1997/1998 945:



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Old 08-13-2022, 09:38 AM   #14
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You’re in the…UK? RHD model?
The car’s likely to be crusty from salt air/roads in The drippy (or scorching hot at the moment?) UK?

I confess I’d just swap in an ‘84.5 (has the tapped bosses for the preheat manifold / alt heat shield in the case or a 240 or PS return hose heat shield in the case of a 7/9 ~’84.5+) to 1988 LH2.2 n/a manifold w/the O2 sensor threaded boss many times?

The ‘84.5-‘88 pre heat manifold is different from ‘89+, but they swap/same bolt pattern to the iron manifold, &, apart from a little rattle cold sometimes, ‘89+ style shields other stuff in the engine bay a little better as well as manifold from spray etc?

There’s definitely some inherent risk to doing this swap; the head studs are prone snap on removal with age & likely to be crusty, temp cycled snd brittle & definitely it’s more bolts than just having an exhaust shop weld in a pipe with an O2 bung or cat with an O2 bung? Or getting out your wire feed welder & step drill bit & DiY for your own re-introduction or the 02 sensor & home ‘test pipe’ where the kitty used to be?

On n/a models with good penetrating oil, temp cycling & lots of Wire brushing the studs with a good brush in the drill/flex shaft, nuts will usually come off the studs & go back on ok for me (old & crusty as these cars are now?)? Turbo cup washers can be nice to extend stud life used on N/A Volvos…

That said, I have good used ‘84.5-‘88 iron manifolds from cars ive cut up as well as cherry picked OE downpipes to fix LH2.4 models that seem to be the last gasp for RWD Volvos here & ‘what’s for dinner’ of RWD Volvos, anymore…?

That said, with good flat smooth surfaces & radial knurl nuts between manifold & downpipe on the 3 M10x1.5 studs getting a good OE downpipe to manifold gasket to seal up is often a lot easier and if there are any leaks in a cracked / flexed around fatigued late model downpipe & the O2 sensor is in the front of the catD the O2 will read lean and computer will make the car run way rich.

With the earlier setup,
a tiny pinhole is no big deal & O2 will read accurately as long as the exhaust gaskets between the cylinder head & iron manifold are any good (never seen an n/a manifold crack in the n/a SOHC unless hit by a lot of cold water) & downpipe to iron manifold gasket isn’t leaking too badly in my experience.

But, presence of cat is irrelevant (cats are for pussies & if you aren’t required to pass an emissions test, why have one under the car as low hanging fruit to be nicked in the first place in the wretched times we live in?)

The n/a manifold has the O2 sensor machined threaded spot on USA 4-cylinder SOHC K-lambda & LH-jet models ‘78-‘88.

I suspect they installed the heated O2 in the front of the cat for more precise pre cat trim & consistent temp control on (more) modern heated O2 sensors? &, to keep the sensor from running as hot as it did in the iron manifold and maybe increase O2 sensor lifespan slightly?

O2 installed in the iron manifold is partly a relic from pre ‘84.5 N/a Volvos & 240Turbos with 1-wire non-heated 02 sensors to warm up faster & stay at temp idling &/or cruising I suspect?

That said, it works in the manifold retrofitted to 2.4 models, lasts fine, & then it doesn’t matter what style downpipe or cat you run (or lack thereof?) / what’s downstream of the iron manifold?

I also like it being in the engine bay/not under the car should I need to inspect, clean (white gas & alcohol dip & scrub with appropriate brush & air gun with box fan blowing behind me, usually) &/or replace the O2 with another random decent condition junkyard heated Bosch O2?

I might not think this if I had to work around the steering shaft, brake booster servo, clutch master cylinder disaster for service of the exhaust side or the engine on a RHD SOHC Volvo…never had the ‘pleasure’ of dealing w/one of those…caveat emptor?

The OE ‘82-‘84.5 ‘double step’ down pipes seem to fatigue the least on 2 series & have the thickest best metal in them/I hoard those along with the brackets/hardware with the spring bracket tho they can rust out on the salt cars (usually you don’t have much of a car left / that isn’t also rusted out by that point? ), eventually…

They’re not as quiet as the late model ‘84.5-‘85+ downpipes with the asbestos? Blanket and spot welded stainless? Crimped around them quite but not bad/tolerable/certainly way better the. The aftermarket & thin metal aftermarket downpipes…

Clear as mud?
Good luck?

I certainly wouldn’t delete the O2…unless you want worse fuel economy, stinkier exhaust to kill brain cells & worse engine longevity?
Or something?
Not with an LH model, anyway…k-lambda to K-basic B21F——>B23E &/or B21FT——B21ET has a certain logic?

Even the higher performance B230ET motronic no-cat unleaded gas models have an O2 sensor tho?

I don’t think the guys in white lab coats at a Volvo & Bosch’s extensive millions & billions of dollars & capacity to ramp up to produce millions of cars at their R&D, testing facilities &/or factories & accountants/bean counters would go to the trouble or expense of O2s on even later no-cat models if it weren’t of *some* benefit for longevity, warranty claims, &/or ease of operation for the driver as long as they don’t have to run leaded gas, no?
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Last edited by Kjets On a Plane; 08-13-2022 at 10:12 AM..
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Old 08-13-2022, 04:14 PM   #15
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If you can find a leaded gas ECU for a B230G (last three digits 900) car it will run fine with no oxygen sensor.

Don't do that, though.
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