Brickster's,

You read the subject line. Is it possible the original sensor on this Regina system NA 940 '93 is still operating properly?

The car needs a little maintenance for the upcoming winter. Should I change it out? Where should I buy one?

Oil consumption is roughly 1 qt, per each 3,000 mile oil change. I'm happy with that. Using dino oil because it is way too late to switch.

Idle is choppy. Looking for vacuum leaks but can't seem to find one. Throttle body recently cleaned. Flame trap religiously maintained.

New plug wires last year. Might venture to pull the cap and take a look in side.

Just cleaned the trans screen on the last change and it shifts better than one could expect with so many miles on an original tranny. Also religiously maintained and flushed regularly.

Mark

Your O2 sensor is most assuredly frozen in place. Heat the sensor and the pipe red hot with a butane torch, have a big ice cube immediately available, put the cube on the base of the O2 sensor without touching the red hot pipe. The cube will shrink the O2 sensor and the rusty seal will break.
--
Keith in Maine - 1990 740GL Wagon 245k AW70L B230F Red Block 8 Valve Non-Turbo Rex/Regina Non-EGR R-12 A/C

Hi Mark:

You can measure the function of your O2 sensor so you don't have to guess! It is a three wire system, two of the wires will be the same color, the third will be a different color. The same colored wires are for the heater (probably white) and the different colored wire (probably green) is the one that carries the signal you need to measure. You can access this wire at the firewall-- just trace the harness up from the sensor to there. You can peel back the rubber cover over this connection (a spade connection) but leave it connected.

If you have a volt-ohm meter, set it to volts DC. With the car warmed up completely measure the voltage output of the sensor-- it should swing from about 0.15 to 0.9V at a rate of about once per second. If it is pegged in either direction, or the range is truncated, you need a sensor. Given the miles on your car, I'll bet that the range is somewhat diminished and you will see mileage benefits from a new sensor.

Good luck!
--
Herb Goltz, London, Ontario, Canada '92 245 w/109K mi

". . .measure the voltage output of the sensor-- it should swing from about 0.15 to 0.9V at a rate of about once per second","

Herb,

He has the Regina FI system. The Tinania-based O2 sensor doesn't produce any voltage. The 2 paragraphs below, from web searches, explain it better than I can.

>>Compared to the more common zirconia O2 sensors, titania sensors have three advantages:
(1) they don't need an air reference (there is no internal venting to the outside atmosphere to plug up);
(2) they have a fast warm-up time (about 15 seconds); and
(3) they work at lower exhaust temperatures (they won't cool off at idle and they can be located further downstream from the engine or used with turbochargers).<<

>>This oxide does NOT have the ability to produce a self-voltage. Instead, in automotive oxygen sensor applications, a resistance is measured ranging from a low resistance of 1000 ohms (when the engine air/fuel mixture is too rich) to a high resistance of over 20,000 ohms (when the air/fuel mixture is considered too lean).<<

The Bosch "Universals" will NOT interchange with this type of sensor.

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

I'd add to the good adice so far that you might try cleaning the throttle body. The best way is to remove the throttle body and clean it out thoroughly. I've had good results by removing the large air hose, wrapping a rag soaked in cleaner around my finger, and then reaching in to clean the area around the throttle plate and the edges of the throttle plate. Don't use regular carb cleaner, they sell a throttle body cleaner in a spray can. This made the idle smoother.

I have a '93 940 NA Regina wagon. The camshaft mounted distributor cap was about $30 as I recall. I had trouble getting plug wires which would fit into the cap which was different from the cap used for the LH system. You might try FCP Groton but I'd talk to someone, not just order on-line.

If you do much driving -- and at 240K, it seems you do -- I'd replace the O2 sensor simply as a preventive measure. As Steve pointed out, with gas at $2 plus per gallon, it doesn't take long for it to pay for itself. Even if the sensor is not bad yet, how much more life could possibly be left in it? The sooner you do it, the more return you'll get from your investment. Spook is right on with his advice too (as usual) but I'd expect higher mileage. My friend with the same exact car gets 28-30 mpg at steady highway speeds. If you're not that high, the O2 sensor could be the reason.

Also, go ahead and get a new cap and rotor. A Bosch cap is about $6 from www.fcpgroton.com , the rotor is $3-$4. Well worth the investment. (Especially when you consider the cap & rotor for my '93 945T is over 4 times that!)

Good luck,

Jeff Pierce
--
'93 945 Turbo ( one kickass family car ! ), '92 Mercedes 190E (my daily driver), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece -- sold to a loving home), '85 Jeep CJ-7 w/ Fisher plow

I agree with Spook, although the economics of a new oxygen sensor with $2 per gallon gas are fairly compelling.
And your tranny screen: that should NOT show lots of gunk, unless this is the first cleaning.

Dear Mark,

Good a.m. and may this find you well. You might want to clean the Idle Air Control Valve. It is mounted on a bracket, beside/below the intake manifold.
It has two black rubber hoses and one electrical connector. With the ignition off (and battery negative cable terminal clamp removed), disconnect the electrical connector (press the release, to do so). The hose clamp screws require a 7mm socket. The hoses can then be "wiggled" free. The valve is secured by two hex head bolts.

Clean the valve used carb or choke cleaner. Flush thoroughly. You can use a cotton-tipped swab, but be sure to flush out any cotton fibers. If this does not smooth the idle, the valve may need to be replaced. It might be wise to get one from a salvage yard (from a low-mileage donor, if possible) to check that yours actually needs replacement. Usually cleaning restores smooth idle.

As to the oxygen sensor, how many miles/gallon do you get? If you're getting 20-21+ mpg, then the sensor likely is OK. Has mileage fallen recently, to any noticeable degree? I gather that when oxygen sensors go, mileage falls. If you've had the car since new (or 30K) - and the mileage has been steady - then the sensor likely is OK. If you got the car long after 40K, the sensor could long have failed, and the mileage has always been below normal. I look forward to comments from on-Board experts.

I'm curious about your tranny filter. How long had it been (months or miles) since the last filter change? Was there much on the filter? Could you see any: (a) metal particles or (b) clutch plate fibers? What, if anything, was on the bottom of the pan?

Hope you can improve the idle, and look forward to your comments on the tranny.

Yours faithfully,

spook

Thank you all for your help.

Spook,

I will check the IAC. I bought a can of gumout carb cleaner this morning.

The car gets 24-25 on the highway at 75-80 mph and a combined 21 on average.

I have only had the tranny filter and gasket changed once. Over 100k since last done. But in the meantime I regularly flush the tranny with Mobil Dexron ATF from Costco. $13 per case. I run through 11 quarts or until the fluid is bright red and clear. I do the flush every 20k. This time I took the car to my local trusted tranny shop and had them change the filter. The mechanic was fairly conscientious and could not remove the dip stick tube coupler so he pulled the starter bolts out and the dip stick tube came out with the pan. The screen was perfect. There was the tiniest bit of sludge material in the pan. I would have to say the total mass (after he pulled the drain plug and let about a gallon out) was less than a half teaspoon. Is that okay?

For good measure I am going to change the plugs when I clean the IAC.

Spook...you gonna dress up for Halloween this year?

As always, thanks for your help.

Your friend,

Mark