SaabCentral Forums banner

1 - 19 of 19 Posts

·
Registered
Joined
·
166 Posts
Discussion Starter #1 (Edited)
1985 900 T16 Oxygen Sensor Test - APPARENTLY WRONG / W.I.P.

**NOTICE**

This appears to be bad procedure.

Work In Progress

** ** **

Compared to most here, I do not have the experience and know-how to perform what are probably considered the most basic procedures.

I asked a while ago about my oxygen sensor - testing it.

In case anyone else feels as daft as I do, here's the basics. I'll edit this post to include specifics re: numbers and temps.

For now, here's the basics:

Grab your multimeter. You are looking for a powered (with a battery in it) analog meter. This is because the needle will be moving faster than many digital meters respond. More later.

Start your engine, let it idle and come up to normal operating temperature.

Have a care for moving & hot parts. In particular, the oxygen sensor itself is stuck inside the exhaust, right next to your battery.

Stick the negative lead to the negative battery terminal. An alligator clip would be helpful.




Peel back the rubber boot that covers the "reference" line connector from your oxygen sensor. Stick (or clip with an alligator) the positive lead into the connector.




After attaining normal operating temperature, either with your hand on the throttle lever or with the assistance of a lovely assistant, bring the engine to 2000RPM. With the multimeter set to 10V range DC, if your sensor is operating properly, you should see the needle wiggle. Since the multimeter is set to 10v range, you are looking (with this multimeter, YMMV) at the bottom row of numbers in the black section in the center of the display (0 2 4 6 8 10). Since the sensor produces a signal that fluctuates from 0.2V to 0.8V, the needle will wiggle between the 0 and half of the way to the 2.



CORRECTIONS & DETAILS SOLICITED / WILL EDIT.
 

·
Registered
Joined
·
166 Posts
Discussion Starter #2
And here's the actual problem:

My test is bad due to operator error,

or,

my O2 is dead, since the needle did not so much as budge,

or,

something else.

I had one particular individual insist that I should have been checking ohms, not volts. So I did. Same nothing.

I also checked (both) with the negative lead to ground instead of the negative battery post. Same nothing.

I also checked a few other random bits (for voltage), and got all sorts of nice readings. The multimeter (and battery) are brand spanking new.
 

·
Registered
Joined
·
166 Posts
Discussion Starter #5
Thank you both for the /very/ informative replies!

Any tips/tricks to getting it out? It is very tightly rust/welded. Liquid wrench (obviously when cool)?
 

·
Registered
Joined
·
8,923 Posts
Thank you both for the /very/ informative replies!

Any tips/tricks to getting it out? It is very tightly rust/welded. Liquid wrench (obviously when cool)?
They remove fairly easily and not normally rusted solid. But you will need a special wrench that is slotted to fit over the cable. This is one example.
 

Attachments

·
Registered
Joined
·
166 Posts
Discussion Starter #7 (Edited)
Thank you.

It turned out with a combination of:

Liquid Wrench (applied with the engine cool)
Time
22mm box wrench
Moments & Newtons

I am especially pleased to have not rapped my knuckles against the turbo assembly or the distributor when it broke loose.

I did notice some nearly white greyish accumilation inside the housing penetrated by the O2 sensor (same as that which coated the old O2). Is there any value to disassembling these rather rusty pieces and cleaning them out?
 

·
Registered
Joined
·
166 Posts
Discussion Starter #8
Clearly I am doing something wrong.

As indicated by the (updated) procedure, I have:

Multimeter black lead clipped to negative post on battery.
Multimeter red lead clipped to disconnected reference wire.
Multimeter set to 10v (lowest available DC range)
Engine at idle temp.
Manually bring RPM up to 2000 RPM.

I am still getting absolutely no wiggle whatsoever with my brand new EIGHTY DOLLAR Bosch O2 sensor.

Resistance across the two heater pegs is 7 ohms. FWIW, the old sensor reads at 6ohms.

- - - may not exactly be related, but this is the gremlin I am chasing - - -

Car still stumbles under the following circumstances:

Hotter engine (past about 1/3 into green on guage); and
Under any significant load, e.g. anything greater than granny acceleration, or dog forbid, a hill.

Before the car gets hotter (these days, these temps), it blasts into speed like a rocket on rails.
 

·
Registered
Joined
·
12,939 Posts
O2 sensors work in a very narrow range. Way too rich or way too lean will yield no reading. Look at a plug to find out.
I can't diagnose your car over the internet but, given your symptoms, I'd suspect a faulty Air Mass Meter or NTC resistor. The resistor can be measured, the meter can't.
 

·
Registered
Joined
·
166 Posts
Discussion Starter #11 (Edited)
Well.

My new Bougicords showed up today.

Problem solved.

Although they are /the/ part number recommended for a 1985 900 t16, they a *terrible* fit.

The spark-end stalks are a full inch too tall, causing them to bend a bit with the spark plug access plate in place.

They also abut the cross rails between the head towers under said plate, giving rise to some concern of rubbing wear over time.

They cables are a bit short too, making for a rather tight fit to the distributor cap. As presently installed, the cap will not be able to be removed (should I need to) without first removing the cables, risking losing track of which goes where.

But the car runs amazingly now. No stumbling anywhere, including at the top end of boost. Pursuant my other thread re: typical boost performance, when the APC guage gets to the top it no longer kicks, it just stops rising and if I keep the pedal pedaled, it does slowly back off.

Happy summer drivings!

And thanks to all for your suggestions, inputs & links - I do feel that I learned a few things & I appreciate the energy and time you all put forward.
 

·
Registered
Joined
·
12,939 Posts
The NTC resistor (Negative Temperature Coefficient) you mention - that is a.k.a. Coolant Temperature sensor?
Yes. I tend to use the old names they taught us in SAAB Service School.
Thus Hall Effect Transmitter instead of hall sensor. Air Mass Meter instead of Mass Air Flow sensor.
Old guys talk funny....
 

·
Registered
Joined
·
2,834 Posts
o2 sensor removal, hit a blue flame to the outer neck til red and remove. Since o2 is being replaced i crack the body off o2 sensor, much easier to deal with nut once wire is outta way.

should add that I take the macaroni flange off and put in vice, to me it's just easier to deal with o2 then and takes only few min. to do so.

In midwest and 20+, I've never had one just "come off" without a fight.
 

·
Registered
Joined
·
166 Posts
Discussion Starter #16
Don't do yourself down Jim. You're young from where I'm standing.
I might add you don't have to be old to talk funny.
A lot of rubbish comes out of young heads.
Guilty as charged. :)

Regarding removal of the O2, an acquaintance recommended dousing it with brake fluid and then heating it with a torch. I didn't have one handy so I just ran the car, that pipe gets terrific hot.

Whether or not it helped I cannot say since I didn't run a control... ;) but it did come loose.

Now I have an OCD-level desire to remove the manifold, elbow, and downpipe and polish them, inside and out.

Another day, another driveway.
 

·
Registered
Joined
·
12,939 Posts
Brake fluid is quite flammable and not a good penetrating fluid.
Driving the snot out of it to get the manifold hot as hell is a common practice.
 
1 - 19 of 19 Posts
Top