1991 740 auto sedan with 157,000 miles on it. For past couple of weeks I have checked, cleaned, and replaced everything I and Brickboard could think of in an attempt to improve my bad gas mileage(16 around town 22 highway). However no improvement. At this point I think I give up and am resigned to poorer mileage then I had been expecting. Previous Volvo's I have had did about 18 around town and about 27 highway. Then again they had Bosch fuel system whereas this car has Regina system which I have never had before. Maybe Regina system just doesn't deliver as good a mileage as Bosch system ??? What if any are positives about Regina system versus Bosch ???
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' 91 740 sedan nearly 157,000 and ' 87 240DL auto nearly 135,000

Hi there. Interesting setup. I would do a compression test. I had mileage that slowly dropped for years, despite my best attempts to improve tuning. It had a crack in the block, which had been repaired, but always consumer coolant. Long story short, the head gasket finally gave way.

I'd check that, clean up your electrical connectors. I would also get a spark plug tester and see that each plug has a good, solid spark.
Something I didn't see mentioned was wheel bearings. Both bricks I've had wound up with failed bearings after 200K miles.

It's hard to test an O2 sensor because part of the job of the sensor is to respond quickly to changing O2 levels. An old sensor can still sweep through the whole voltage, but may not sweep quickly enough to do its job correctly.


Happy Bricking and here's to improved mileage.

PS Not to be insulting, but don't forget things like tire pressure.
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1990 740 Turbo, on its way to stock specs, maybe beyond

This post inspired me to check my own mileage ( '92 Regina wagon ) 18 mpg combined. Thats with 22 miles total to and from work a week plus a 1 or 2 40 mile weekend trip half on the expressway at 60 to 70 mph. Enough waiting at stoplights etc. When I commuted with mostly expressway miles I got 20-21 mpg. I have a Saab 9000 5 speed that the trip computer shows 24.5 mpg on the same routes. I hear the trip computers can be a bit optimistic with the mpg estimates though, and the saab does 500 rpm less at 60 mph than the 740.

I'm tempted to replace the o2 sensor and see what if anything happens.

I too am tempted to replace O2 sensor. However it is not throwing off a bad code to my OBD. Actually my OBD shows all being fine/no problems. I tested my O2 sensor as per procedure found here within Brickboard and it tested out to be okay. You may want to check your OBD codes and also you may want to test your O2 sensor. Not a cheep sensor. Nearly $100.
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' 91 740 sedan nearly 157,000 and ' 87 240DL auto nearly 135,000

In addition I suspect my o2 sensor may be an aftermarket and/or incorrect replacement. The only time I had an o2 code set is when I accidently created an exhaust leak at the converter to header flange. Last time I checked for codes there were none but the normal 111. This weekend I will be cleaning out my oil separator to try to alleviate the oil being drawn into the small vacuum line. Flame trap and all other crankcase vent items checked and ok. If I can fix this I'll see about the $110 o2 sensor from Eeuroparts. btw...the Bosch sensor for bosch systems is $150 from them...I do have 220k miles and I don't think my car was babied for at least 100k prior to my purchase..

The correct NGK/NTK sensor is about $88 at AMAZON.COM
>
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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

I'm sure this sensor from amazon is the direct fit. But when I check the "Make Sure It Fits" it says it fits bosch front with turbo. Obviously an error. I get nervous when ordering parts so this little thing scared me away. There is a review saying it fit a 940 Regina so it must be the one. I spent over $1000 at Eeuroparts so maybe they can do a price match and I can save the tax also. I'm going to check the wire colors on mine tonight and see if they are correct. My wires have either been cut and spliced back for the newer cat. Or a replacement, possibly incorrect is installed.

...

The "See all vehicles this product fits." link gives a more accurate listing of Regina cars
(but is still wrong in listing 740 and 940 turbos).


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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Hi Bruce
Why is my 1990 740 b230f w/regina not listed for this product? I see 89-90 for the b234f(dual overhead cam) but not the b230f...different cat?
Matt

Guess that list is incorrecter than I realized.

My guess is that the people who make those listings are too removed from the real world to be accurate. The 16 valve shouldn't be on there either.

Basically the Regina FI is on any 740/940 8-valve Non-Turbo from '89 to '93, and possibly some '94 940s (not sure on the '94).

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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

I was getting roughly your mileage or a bit lower with a 1991 740 Regina 8-valve. FWIW, I changed the plugs, cap, rotor, and spark plug wires - but not all at once. No difference until I changed the wires (Bougicord) - which I did last. Mileage is now 20-21 around town and 24-26 highway depending on speed, AC on/AC off, etc.

Very interesting. My wires "look" good but not sure how old they are. Did not know this was a wear as they get old they loose function type item. Always thought that they either work or don't work. I thought spark plugs were more of an important functional item. Is there a way to test wires to determine if they are working 100 % ??
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' 91 740 sedan nearly 157,000 and ' 87 240DL auto nearly 135,000

Use a VOM (volt/ohm meter), or better a DVOM (digital meter), to measure resistance between one end and the other. Induction, by the way, doesn't amount to much in a straight wire (instead of a coil). Look up the specs for what the resistance in the wires should be. I think that the wires are usually specified as having some resistance, simply to lessen spark interference on the radio, but if you don't use the AM band (or can tolerate clicks if you do) you can switch to solid core wire that has negligible resistance.

My motivation for changing the wires was the front plug wire would drop off on occasion, probably due to engine torque/vibration. Annoying, so I finally changed them out. Went from 240 mi/~13 gal fillup to 325-335/~13 gal with my combined city/hwy driving. Pleasant surprise.

I suppose it would be difficult to measure or test - older wires are most likely passing less voltage/amperage to the plugs due to induction loss or whatever. But since the plugs still fire, the wires are effectively working - just less efficiently. As I recall, they were not expensive.

I had that square coil pack replaced later on. After that there was a small improvement in mileage (to 335-355/~13 gal) for a couple years, although it's dropped back off now. It did raise and smooth the idle a bit - also to my surprise since I'd been looking at the fuel delivery system for improvements there.

Yeah, I get a consistent 27 - 28 on the highway. You may want to check/replace your map sensor, also check the vacuum lines that attach to it, there is an elbow line underneath it that can crack and leak. The MAP sensor is identical to on used on a GM car, can't recall which at the moment, if you get the model, NAPA can supply.

Mike

My 1990 745 w/Regina got 28-30mpg on the highway.

I'll argue that Regina is probably superior than Bosch in every way.... it just needs to be working right.

Test all of the sensors. Make sure the brakes aren't dragging, and the fuel tank isn't leaking anywhere.

How old is the O2 sensor?

-Ryan

Thanks for reply Ryan. Didn't mean to knock Regina system . It's just that it is new to me and I was just thinking it was not as efficient. So I guess seems it is not problem with my low gas mileage. All sensors tested and are fine. Replaced engine temp sensor weeks ago as it was bad and causing car to idle way too high. Brakes are not dragging. After a twenty minute high speed run hubs and calipers not unusually hot. No fuel tank leaks that I can smell or see. O2 sensor tested out OK. Not sure how old it is as I just got this car late July. No records from previous owner. Could be pretty old based on lack of replacement of other items such as fuel filter(I have since replaced it), exhaust system(since all replaced from header pipe back), etc. Although it tested ok do you think it might help to replace it ?? Not cheap - a little over $100 but if it might help I would replace it. Thanks.
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' 91 740 sedan nearly 157,000 and ' 87 240DL auto nearly 135,000

Might be worth replacing the O2 sensor. For cars that have adaptable EFI and a single O2 sensor, that sensor becomes really important.

Has the car been smogged at all? That would tell you something. Otherwise, it's hard to say if the O2 sensor is telling the truth.

We don't have emissions testing here in Ohio. I just bought an NGK O2 sensor for our Regina-mobile on Amazon.com. It was 'only' like $80... which is what you'll pay for a direct fit Bosch sensor.

-Ryan

"...which is what you'll pay for a direct fit Bosch sensor."

Ryan,

I'm sure you didn't mean to suggest there is a "direct fit Bosch sensor" for the Regina FI but you know how those casual readers can muddle things up, right?


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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Good catch! :-)

I should have written: "...a direct-fit sensor for the Bosch system".

Thanks again for pointing out the NGK sensor on Amazon.com... Gotta get the 740 back on the road again!

-Ryan

that's about what i get. but then again i driven like a douche and my regina is turbo-ed...

OP back. While I guess I should appreciate the thumbs up I do not understand why it was given. Although I have tried everything I/brickboard could think of I still ended up with what I feel is low gas mileage. Problem unresolved. So I feel thumbs up is unwarranted but thanks anyway whomever.
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' 91 740 sedan nearly 157,000 and ' 87 240DL auto nearly 135,000

Hello,


There are quite a few things that you need to inspect. Don't just change the spark plugs and then call it over!

You should be running synthetic oil. I prefer Mobil 1. It can add 2 - 5% mileage.

Yes, the engine is important. YOU NEED TO HAVE A FIT CHASSIS TO GO ANYWHERE!

I really doubt that the alignment is perfect. Even if you had it aligned somewhere, you need to see the numbers. I like to have my car aligned at the dealer and watch the computer. Every car I have had aligned had damaged parts. It takes very little to tweak the arms out of true. The damage is cumulative, like a bike rim. Given that the curb jamming and wheel slamming history is unknown for this vehicle because you bought it used, you need to start here. Replace ALL damaged parts and have it aligned again if you are at all serious about fuel efficiency. Get the numbers too!

Are the brakes dragging, are the hubs hot? Go on a highway drive and don't use the brakes for a few miles. Use engine braking. Get out and feel the rotors, hubs, and tires. Any abnormal heat indicates friction and energy loss.

The chassis is the most important part of the car. The engine is more complex, but the chassis carries the engine!



Good Luck!

OP back. Thanks for replies. My O2(oxygen) sensor is indeed the correct one. I checked. Also I checked/tested it(per Brickboard) and it is performing correctly. I was thinking of replacing it prior to checking it. Even if it were bad(which I do not think it is)could if lower gas MPG by that much(in my case aprox. 25%)?? Seems there are conflicting opinions on just what mileage this car should get. My opinion is that it should equal or better my deceased 1988 740 wagon or my other car which is 1987 240 sedan(both auto, both non turbo, both Bosch system). Maybe I am wrong. Maybe what I am getting is normal ?
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' 91 740 sedan nearly 157,000 and ' 87 240DL auto nearly 135,000

You say, "My O2(oxygen) sensor is indeed the correct one."

How was that determined? Are the 3 wires RED, WHITE, and BLACK? If not, it's the wrong sensor, which will definitely result in poor performance and poor mileage.

I've never checked, but the wrong (Bosch type) sensor signal may look OK on quick voltage check at idle. They both work in about the same voltage range.

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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Your driving style makes a huge difference as well. I drive very aggressively and regularly do a 80mph 20 mile run back and forth to work and I just calculated my MPG this am at 21.25mpg. This of course was with the A/C on virtually all the time as well. I would imagine if I mellowed out a bit and just did 65mph I could achieve 25-26mpg...but what fun would that be:)

"Seems there are conflicting opinions on just what mileage this car should get."

I don't know of any conflicting opinions on Regina mileage. Not in this thread anyway, at least so far.

The B230F operating specs (HP, Torque, Fuel pressure, etc.) are the same for Bosch and Regina, so its reasonable to expect comparable mileage for the two systems.

My 940 doesn't see enough "city" driving to calculate MPG, but my usual semi-rural average is in the 24-26 range, with 26-28 highway. The highway mileage improves to 28+ if I make the effort to keep speed at 70 or lower.

I don't have any experience with poor Regina performance (yet), nor is there much history on it to be found here on the BB. So I'm sorry to say that I don't have any new tips to offer.

Have you tried a search here on Regina mileage?
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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

We have been getting between 24 and 28 mpg on every tankful for the last few months on our Regina 940 after replacing the O2 sensor and doing a major tune up. I think having the kickdown cable disconnected helps the mileage (have been intending to fix this but never got around to it), but you have to drive it like a standard for passing etc. Most of our mileage is on single lane and rural roads. Our 940 gets at least 10% better mileage than our 240.

Ron

93 245
93 944

I guess with your poor mileage I would confirm that your ECT sensor and your O2 sensor are the correct ones for your car.
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Post Back. That's whats makes this forum work.

yes, the O2 sensor is unique to the Rex/Regina system and costs MUCHO DINERO!! I just replaced the incorrectly installed Bosch on my daughter's car and while I have not checked the gas milage, it seems to not be excessive.
good luck,
el raidman

hello
i believe you can get the sensors for around 100 bucks. i found a few in the yards that werent removed with the cat.
the older regina/rex had the 02 sensor just in front of the cat and when they cut out the cat sometimes the 02 sensor is still there. like 4 bucks if you get lucky and find one.
your gas mileage is poor and regina should be a little better or equal than bosch.
maybe your engine is tired.
good luck
mike

I wonder what lucid gets, he has the most detailed coverage of the Regina system.
Others with that system have claimed as much as 32 mpg highway, which I found beyond belief, but they were convinced it was so. Many have claimed in the high 20s also.

I just checked my 93 940T, which is Bosch, again, combined city/highway, 19.2.

http://www.fueleconomy.gov/feg/noframes/10100.shtml

Fuel Type
Regular

MPG (city)
17

MPG (highway)
22

MPG (combined)
19

hello
i believe bruce gets 27-28 hwy. i know this because we have same car as him and have talked about this.
my 94 940 turbo would get 24-25 strictly hwy. 21-22 in town. that is before i put in a m-47 and changed the rear end.
we had a bosch 94 940 non turbo that would get 27 easy on the highway.
good luck
Mike