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Some of us are still looking for a definative statement that the Regina system uses a fundamentally different kind of Oxygen sensor from the Bosch systems. Does anyone have a green book for Regina, or other authoritative source that says something like "Regina uses a Titania sensor" or anything else like that that might convince us that we cannot use the generic (zirconia) sensor.
Any help is (as always) very much appreciated.
--
Andy in St. Paul, '91 745 Regina 188K mi, '89 244 136K, '87 245 RIP
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I have a "definite" answer from looking at the voltage levels. There's no voltage coming from the sensor when I unplug the ECU side (green wire) of the spade connector, nevertheless there *is* a voltage on the ECU side of it. It can only indicate a resistive sensor. An ECU input for a voltage output O2 sensor will have a tiny leakage current and there'll be practically no voltage present on the input.
Cheers, Kuba
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posted by
someone claiming to be lost
on
Fri Apr 30 16:27 CST 2004 [ RELATED]
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I just bought a NGK (NTK) O2 sensor (25002) this morning that is for the Regina system on my 91 740. I got it from NGK.com and was actually able to get $10 off too with a coupon code. so its under 120 with the shipping. I had emailed back and forth with the NGK people and he reccomended this one too me.
I was the one getting 16 mpg because someone had cut the O2 lines and rigged up a bosch sensor before I owned the car. I'll let you know once I have installed it, what the difference is.
tomtbone
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It will be good the hear what your experience is. Thanks Tom.
--
Andy in St. Paul, '91 745 Regina 188K mi, '89 244 137K, '87 245 RIP
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from the lh 2.4 wsm dated 3/93
code 212-o2 sensor signal absent or faulty.
testing-engine is warm, use meter on o2 connector and look for 0.1-0.9v.
to check voltage supply to o2, disconnect 02 connector, check for .5v on lead from ecu.
from the regina/rex wsm dated 9/91
code 221-os sensor signal absent or faulty.
testing-engine is warm, use meter on o2 connector and look for 0.1-1.2v.
disconnect o2 connector, check for 1.2v on lead from ecu, after a while.
to check voltage supply to o2, uplug heater connector and look for 12v on pin 2.
so the lh gets it's voltage from the ecu at .5v and the bendix get it's voltage from the heater circuit and it's 12v. good enough for ya? and so it goes, chuck.
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It IS good; finally.
Thanks, Chuck, and all.
So it continues to be true that Regina might be a nice ride, but she isn't a cheap date.
--
Andy '91 745 186K, '89 244 135K, '87 245 lost the rust battle at 225K mi
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Well... I don't know if this is the "smoking gun" you are looking for, but here
http://www.autoelectric.ru/auto/volvo/740/1989/740-89.htm is a series of electrical schematics for the various ( bosch and regina) systems. Look at item # 187 (O2 sensor) for the various Bosch injection systems, and then look at the Regina. The Bosch sensors have a separate circuit for the signal feed, and one for the heater. The Regina's are connected ( signal and heater) internaly to provide the base signal voltage for the ECM.
When I first went to test the O2 sensor on the 94 940 by allowing the car to come to running temp then unplugging it, my first reaction was WTF! No volts, dead. &*%$! But then I remembered the 88 Jeep with a Titania type I had worked on a while ago, and for giggles put the DMM on continuity. It lives! I was getting correct ( for a Titania) resistance swings. Then I hooked it back up and then back probed the connection. Correct voltage! This one is original with 135000 miles on it,
and after changing the plugs today (that had been in 30k that were nice and clean with just a small amount of light tan residue) is still doing a resonable job. The Regina sensors may be a PIA to locate, but they seem to be long lived.
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The Bendix/Siemens fuel sytem models use a different type sensor and it is not interchangeable with the Bosch units. This sensor does not work with a .5 V reference out of the ECM as does the Bosch versions. This type uses the heater power supply to feed a sensor circuit responds to O2 level variations. The Bosch type employs an electrochemical reaction and the heater is for stability of the temp (and therefore the signal) and not for the supply of current to be modified and used as output signal.
http://216.239.41.104/search?q=cache:4t_ja5f8dCIJ:www.volvoclub.org.uk/faq/EngineSensors.html+volvo+bendix+regina&hl=en-----this is the link
i found the above statement in the faqs. the reference voltage is what bosch uses to determine return voltage to the ecu. will keep looking. no, i don't speak french. the bendix system was introduced on the 74o gl-cheap car, manual windows, no sunroof, etc-in 88. the bendix sytem is cheaper to buy than the bosch. and so it goes, chuck.
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Andy,
I was on the Walker Products site about 3 weeks ago, following up on Kaz's info on the 250-23811 and 23881 sensors. In the PDF Applications list, I SAW those sensors identified as Titania (and the others as Zirconia), and both of those numbers x-ref OK to Volvo 3517394 in the Walker Applications listing.
Foolishly, I didn't copy or save anything, assuming that I could always go back. Well I tried it today—and something's changed. The list looks like I remember it—same format, all caps, etc., but no more T or Z notations!
A minor point is that the Universal Sensor list PDF graphic shows the 250-23881 with the RED signal wire—which means Titania, as I think we learned from that Polish site.
As said elsewhere, the signal "swings" on each type of sensor may look similar on a meter, and thus the Regina may run on the Zirconia—but not properly. (Someone recently mentioned getting 16mpg running a Bosch sensor.)
P.S. FWIW, nobody typically identifies the Bosch as Zirconia either. We just go by the different part numbers. The trouble began when the Bosch was offered as a "universal". I'll be making an FCP order tomorrow and will talk to them about it.
--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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Thanks very much for all of this, Bruce. You too Art. I know we had discussed this a while back and my original post here was just a hope to flush out someone with that elusive document that Art would agree ought to exist somewhere. Maybe it's published only in French or Flemish and no one has ever translated it.
Good luck with FCP Groton. I use them too and they are excellent. When I spoke to them about this they were clear that they sell the universal for Regina and haven't had complaints, but were not adamant that it was right. In fact, they told me that I could return it if I tried it and it wasn't.
Fortunately for me (unfortunately for answering the question), I don't need to replace mine at this time. Maybe Porkface is right and I never will! Do you speak French, Chuck ?
--
Andy '91 745 186K, '89 244 135K, '87 245 lost the rust battle at 225K mi
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If indeed it does use such a sensor, here is an explanatory note from NGK:
Titania Sensors: The Titania element in these sensors does not produce a voltage like the Zirconia element. The property of the Titania element which allows for the detection of oxygen in the exhaust gas is its electrical resistance. The electrical resistance of the Titania element changes according to the concentration of oxygen in the exhaust gas. There is a big change in the resistance of the element when the fuel-ratio is 14.7. When a voltage is applied to the element in a voltage divider circuit, the output voltage changes with the resistance thus forming the voltage signal required to be processed by the ECU. As with the Zirconia sensor a low output voltage indicates a lean mixture and a high output voltage indicates a rich mixture. These voltages are used by the ECU for closed loop control.
As Titania sensors do not need air on one side of the element, they can be made smaller and are completely submersible. Due to their different properties Titania and Zirconia sensors should not be interchanged under any circumstance.
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Titania can be easily interchanged with zirconia, but you must make a small interface circuit that will essentially apply a gain of 5 to the voltage coming from a zirconia sensor (with roughly 0-1V output) to produce the 0-5V output typically expected by the titania-input ECU. The ECU is providing some small bias current (most probably way less than 10mA) to the titania input pin, but the amplifier circuit should have no problems with that. It actually works (I haven't permanently installed it yet -- have to make a nice wiring harness first) but is not very cost effective if you don't have the parts.
You need a small breadboard, some miscellaneous parts and relevant experience. As I believe a titania sensor could be had for about 95$, and a "universal" zirconia from FCP Groton goes for about $45, you'd need to fit your electronics in 50$ assuming you don't count your time.
Unless you're an electrical engineer or an electronician-hobbyist with most parts and experience at hand, it may be hard to squeeze the electronics in those $50. A decent enclosure (ABS at least) will cost around $10 itself, the breadboard goes for probably another $10, I doubt you can get a spool of decent (at least 120C/250F rated) hookup wire for less than $15 - that's 35 for the very basic stuff. The screw header blocks, the op-amp chip (needs to be rail-to-rail IO), the voltage regulator (even if just a zener diode), some overvoltage/overcurrent protection and other passives plus the shipping (around $7 for a small ground package from DigiKey) will easily add up to about $45. That's still assuming that you have a nice soldering iron and a decent flux-cored solder. You will also need small diameter solid conductor wirewrap-style wire to wire the breadboard itself. OTOH if you're into electronics, you'll probably have everything at hand maybe short of the enclosure.
So for me it was easy to do it, but it probably may not make too much sense financially for the typical brickboarder.
OTOH, once you do the electronics they will likely outlive the car so after initial cost you just change the cheaper O2 sensor :) So it may make sense if you plan on getting another 100k miles from the car at least.
It's also noteworthy that replacing zirconia with titania (don't know if it would make any sense though) would be even simpler, as all you essentially need is 4 resistors, a zener diode and a capacitor in order to reduce the voltage from the sensor and to provide the bias current. This stuff can be soldered together in-line and then just covered in shrinkwrap, no need for an enclosure nor a breadboard. I wouldn't suggest such assembly approach to the titania-to-zirconia interface which is more complex.
Cheers, Kuba
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Thanks again.
I think that might explain what Art Benstein was telling me on how he thought a zirconia sensor might work fairly well even IF it's the wrong one. If zirconia generates voltage based on oxygen content, it might send out a voltage similar to what a titania sensor passes as it's resistance changes.
That's my interpretation of how that might be possible and I really don't understand this stuff. Art certainly does. What we were really looking for is the source of this "knowledge" that Regina uses titania since we haven't been able to find any real documentation stating that.
--
Andy in St. Paul, '91 745 Regina 188K mi, '89 244 136K, '87 245 RIP
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Andy,
I see your quest (and mine to a lesser degree, since I'm not needing a sensor) is still unfulfilled. As you've heard me say before, it seems as if the knowledge is almost kept like a trade secret. Or, perhaps Bendix built the second-source ECU to Volvo's spec which dealt with pinouts (the Bendix and Bosch computers have identical connectors with almost pin for pin functionality) and not necessarily the same means to attain end result.
So, when Bendix chose the Titania sensor, which I believe they did based on the NTK and Walker cross references cited by Steve and a host of others googling for this answer, Volvo had nothing to say about it - done deal. Might have frosted Bosch, if you believe in stuff like that going on in corporate relationships, but I'm guessing Regina exists because Bosch was not up to supplying Volvo's demand one year.
Wish Fitz with his Michigan industry contacts and knowledge would chime in here.
Earlier I proposed a WAG (not even a SWAG) that Bendix may have applied the voltage to the titania sensor that would result in the same stoich crossing point as the zirconia (we know that is Bosch's) produces, which _could_ account for the vague reports of good news using a Bosch universal. Later, finding the curve to be opposite the way I thought in titania sensors, I envision too much design work in the ECU (at the comparator that determines stoich crossover) would be needed to support both types, so I think it was a pretty lame WAG.
I've one Regina in our collection, but unfortunately it is the MIL's 940, 45 miles distant, which she hates to give up for even regular maintenance. I hear (indirectly) she doesn't care for the looks of the loaner 244 I must leave at her house. But maintenance it must have, so I should have an opportunity soon to pull apart the Bendix box and see if anything becomes obvious.
Still, that feature that requires no reference air sounds like it might really improve the life expectancy of the Titania sensor. I know I've killed one Zirconia with outside contamination. Maybe they last so long no one needs to change them, like Chuck says.
--
Art Benstein near Baltimore
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Per the pocket data booklet, Regina cars through 1993 use a Volvo -394 sensor which is the same as NGK OTA4F-B. Tracing that should give you some info.
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the green book makes no mention of what type the regina o2 is. it just covers it's function. the parts dept has 2 part numbers for 700 o2 sensors. and sp it goes, chuck.
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Thanks, Chuck.
The different part numbers COULD just be because of different connectors rather than a real difference in the sensors. We know that many different connectors go on the same sensors which all work with the Bosch systems.
--
Andy in St. Paul, '91 745 Regina 188K mi, '89 244 136K, '87 245 RIP
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i think the connectors are the same. i've never even changed a regina o2, so i can't be sure. buy the bosch and report what happens. it won't act right. if art benstein sees this, he's done the research, he's better up on it than i. good luck, chuck.
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I've talked with Art on this in the past. He hasn't seen anything definative on this either. He has some ideas on how the "wrong" sensor might work reasonably well more or less by accident, but he told me he thinks it's strange that there is no documentation that it is really different even though everyone seems to think it is.
FCP Groton told me they sell the generic to people with Regina and haven't had any complaints.
--
Andy in St. Paul, '91 745 Regina 188K mi, '89 244 136K, '87 245 RIP
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