Allpar Forums banner
1 - 15 of 15 Posts

·
Registered
Joined
·
159 Posts
Discussion Starter · #1 ·
RockAuto had this article which I immediately thought might apply to our PT Cruiser's ?? If not it may be educational to us DIY guys.

----------------------------------
Why does the original equipment (OE) oxygen sensor made by NTK for my wife's 1993 Ford Tempo cost almost $200 less than the OE oxygen sensor made by NTK for a 1993 Honda Civic VX? It is because the Tempo has a conventional oxygen (O2) sensor and the Civic VX has a wideband air fuel ratio (A/F) sensor, a more complex version of the oxygen sensor. The price difference for this example is extreme (I like to brag about our frugal Tempo), but wideband sensors typically cost twice as much as conventional O2 sensors.

One or both types of sensors are found on the newest cars. Often a wideband O2 sensor is upstream of the catalytic converter and a conventional O2 sensor is downstream. A conventional oxygen sensor can only tell the engine computer that the fuel/air mixture is rich or lean. A low voltage signal typically indicates the mixture is lean and a higher voltage indicates rich. This means with an O2 sensor the mixture is constantly being adjusted from slightly too rich to slightly too lean. When the gas pedal is floored, the computer just throws up its hands and ignores input from the O2 sensor until the excitement is over.

A wideband A/F sensor generates a variable electrical current. The direction the current is flowing tells the computer whether the mixture is rich or lean. The number of amps tells the computer precisely how much oxygen is in the exhaust. The computer can keep the fuel/air mixture closer to the ideal setting. Fuel economy increases and emissions decrease. Sometimes the higher cost of the wideband sensor is further offset by the ability to use a less expensive catalytic converter to control emissions.

Both sensors thread into holes in the exhaust pipe and are removed/installed using an O2 socket with a special slot for the wiring pigtail. Their appearance is also very similar. The tip of the conventional O2 sensor usually has more air holes or slits than a wideband sensor does. Wideband sensor electrical connectors have more wires, typically four or five. Both sensors cause similar symptoms when they fail: stalling, erratic idle, failed emissions tests, etc. Neglecting to replace a high mileage, sluggish or dead oxygen sensor could also damage your catalytic converter, costing you an extra $500 -$1,000 in repairs, if not more.
 

·
Registered
Joined
·
3,120 Posts
Why does the original equipment (OE) oxygen sensor made by NTK for my wife's 1993 Ford Tempo cost almost $200 less than the OE oxygen sensor made by NTK for a 1993 Honda Civic VX?
- pricing politics, neither is especially expensive to make.
 
  • Like
Reactions: floridaman2013

·
Registered
Joined
·
1,113 Posts
Why does the original equipment (OE) oxygen sensor made by NTK for my wife's 1993 Ford Tempo cost almost $200 less than the OE oxygen sensor made by NTK for a 1993 Honda Civic VX?
- pricing politics, neither is especially expensive to make.
Agreed. These things have been around for years yet the prices are rip offs from some vendors.
 

·
Registered
Joined
·
3,120 Posts
I keep thinking about setting up some sort of O2 sensor readout; I have a sensor and it would be nice for tuning my Valiant.
All you need is the sensor, bung and a multimeter.
Text Font Blue Green Yellow


The switching point is almost ideal to be in for the engine and a tad more rich at wot.
The diagram is for the std sensor, a wideband set up can show more data.
 

·
Registered
Joined
·
159 Posts
Discussion Starter · #6 ·
The testing of my 88 Mr2 SC is nothing like what I think I see in your graph AC (?What ever that may be?). The Toyota Manual saz to look for 8 or more voltmeter fluctuations in a 10 second period.
 

·
Super Moderator
1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
Joined
·
22,492 Posts
The image shows a single fluctuation from high-to-low. There is no time scale indicated on the image.
On a car that is warmed up and in closed loop, the O2 (or A/F) sensor should be rapidly switching back and forth from about 0.2v to about 0.8v.
If it stands still at center or pegs high or low, there is a problem.
 
  • Like
Reactions: Bob Lincoln

·
Registered
Joined
·
3,120 Posts
Which is difficult to produce with a carb, remember early smog era engines...
 

·
Registered
Joined
·
1,291 Posts
I keep thinking about setting up some sort of O2 sensor readout; I have a sensor and it would be nice for tuning my Valiant.
Dave; there are many companies that sell wide band o2 setups. 'Innovative' is one with an accurate product. They come with the sensor, A/F ratio meter, and wiring. You need to install a threaded plug in your exhaust/header pipe by welding or using a special clamp. About $400.00 list. Probably cheaper now.
 

·
Administrator
1974 Plymouth Valiant - 2013 Dodge Dart - 2013 Chrysler 300C
Joined
·
37,457 Posts
I don't think I need wideband. I like the Ehrenberg solution of using an old junkyard sensor. I'm just doing a standard idle tune of a single barrel carb. I'm putting it off till the fall, I haven't even done an old fashioned tach/vacuum tune yet.
 

·
Super Moderator
Joined
·
32,662 Posts
I don't think I need wideband. I like the Ehrenberg solution of using an old junkyard sensor. I'm just doing a standard idle tune of a single barrel carb. I'm putting it off till the fall, I haven't even done an old fashioned tach/vacuum tune yet.
That will get you as close as you can to ideal.
 

·
Administrator
1974 Plymouth Valiant - 2013 Dodge Dart - 2013 Chrysler 300C
Joined
·
37,457 Posts
I just remember having my Camaro tuned years back by a guy who put it on the meter and it NEVER felt anywhere near that good... I think he got another 2 mpg out of it and it was more responsive too.
 

·
Registered
Joined
·
3,120 Posts
Setting idle mixture by ear is as good as anything.
I turn the idle mixture screw to highest possible idle and then lean it about an eight of a turn or so.
Good idle, co below 1% and i dont get tears in my eyes of the exhaust fumes.
the lambda comes in handy when you whant tune the engine under load ie driving.
 

·
Super Moderator
Joined
·
32,662 Posts
Setting idle mixture by ear is as good as anything.
I turn the idle mixture screw to highest possible idle and then lean it about an eight of a turn or so.
Good idle, co below 1% and i dont get tears in my eyes of the exhaust fumes.
the lambda comes in handy when you whant tune the engine under load ie driving.
This is still a crude method. The proper way is to use a vacuum gauge. Start off near proper curb idle, with mixture screw(s) backed out two full turns, then very slowly turn in until idle just begins to stumble and vacuum begins to drop slightly or be unstable. Then back off in tiny, slow increments, just enough to stabilize the idle. Then set curb idle speed. It's important with this method to go slowly and give the engine time to settle in with each adjustment - 20 seconds or so. Usually less than 1/16 turn at a time.
I brought a 72 Dart with slant-6 from 18 mpg to 24 mpg (at 55 mph, the limit back then) with careful tuning, and the addition of a capacitive discharge ignition, and lighter advance springs in the distributor.
 
  • Like
Reactions: valiant67
1 - 15 of 15 Posts
Top