3800Pro Forums banner
1 - 20 of 24 Posts

·
Registered
Joined
·
346 Posts
Discussion Starter · #1 · (Edited)
With much of the talk going on lately regarding wideband O2 sensors, I thought I'd put a little post out pointing out why wideband sensors make good sense.

The O2 sensor that came stock on our cars is referred to as a narrowband sensor. People should understand that they were designed to provide a feedback mechanism so that the PCM could properly adjust the air/fuel content in order to provide good emissions (clean) performance. In other words a stoich AFR of 14.7. The designers of these sensors (or the car manufacturers for that matter) were less concerned with providing an accurate AFR for good performance. Because of this, the O2 narrowband sensor is extremely accurate at an AFR of 14.7, but horribly innacurate at any other AFR. Here's a pic showing what I mean. I forget the source.



If you look in the "rich" region (lambda<1), you can see that the biggest problem that these sensors have is that they have a bigger dependency on exhaust gas temps than they do to AFR. This pretty much renders the unit useless for any type of accurate AFR monitoring. If you are to assume that the exhaust gas temps stay constant, you could draw the conclusion that these sensors can be used fairly accurately. Unfortunately, this assumption cannot hold true, as we all know that the AFR will have a direct effect on exhaust gas temps, and as the temps increase, the O2 levels will appear to drop.

In contrast, a wideband O2 sensor is much more stable relative to exhaust gas temps and is a much better solution. Unfortunately, they are a little pricey. Some of the more popular wideband O2 controller/sensor kits out there today are Innovative, FJO, AEM, PLX systems, Zeitronix.... They typically range anywhere from around $350 to $700+ depending not only on features but also what sensor they use. Probably the most expensive sensor is the one from NTK, also known by people as the Honda O2 sensor since they were OEM on some models. The NTK sensor by itself usually goes for $200 if not more. The advantage of this particular sensor is that it is more accurate over a wider AFR range, and also responds to changes quicker, giving you a more accurate representation of what's happening in your combustion chambers. It is also claimed to be more tolerant of lead or other heavy metals used in racing fuels. Then there are the Bosch units that most people know about. The Bosch LSU4.2 is the inexpensive one found in most of the cheaper kits. That sensor typically goes for $50 to $100. It's probably fine for most people but it's not the Cadillac of sensors. Then there is the Bosch LSU4.7 that is closer in price and performance to the NTK units.

I hope this helps somebody.

John
 

·
Registered
Joined
·
1,224 Posts
John are these simple replacements of the stock O2 sensor just like we would change out a stock sensor? Or is there more involved in going to a wideband sensor?
 

·
Registered
Joined
·
346 Posts
Discussion Starter · #3 ·
Chris,

Not typically. A narrowband sensor typically produces a 0 - 1V signal, whereas a wideband is usually 0 - 5V so it can't be used as a direct replacement. They do fit the same bung though. :D

Wideband kits require two parts. The sensor connects to a controller of some sort that generates the analog (and sometimes a digital output) used to interface to scanners, gauges, etc.

One of the units I mentioned above, the PLX, has a unique feature though. The controller that comes with the kit has both a 0 - 5V output to be used as a wideband output, but it also has a narrowband emulation output port that simulates the operation of a narrowband sensor for the benefit of the car's stock engine management electronics. It soulds pretty cool in theory, but I would steer clear of that. It seems to me that if you're making enough power to be overly concerned about AFR, head gasket, and piston integrity, the last thing you need is an extra piece of electronics between the O2 sensor and the PCM to fail.

I think the best solution is to have both narrowband and wideband sensors installed. The narrowband to work with the car's stock engine management, and the latter to be used for tuning and checking.

John
 

·
Registered
Joined
·
346 Posts
Discussion Starter · #5 ·
They're "supposed" to work better before the cat, but I don't know how much of a difference that makes. I realize that the probes that dyno operators put in tailpipes are after the cat, but I think those are a different technology.

John
 

·
Registered
Joined
·
1,224 Posts
Interesting John. So you are basicly saying if one is to go to a wideband O2 sensor, its best to leave the stock narrow band sensor in place for the cars everyday operations and basicly wield in a new bung for a wideband O2 sensor. So you will have 2 O2 sensors before the cat.

Have you gone to this or done something similar yet John?
 

·
Registered
Joined
·
565 Posts
Merc, yes, that's what he is saying. Your PCM still operates thru the narrow band O2 sensor, that's why it needs to stay in place. I think a good option as mentioned above is to include the wide band in place of the 2nd O2, especially if you have removed your cat. That way, you wouldn't need to include a 3rd bung in the exhaust.
 

·
Registered
Joined
·
346 Posts
Discussion Starter · #8 ·
Chris,

I'm in the process of pulling it all together now. The new HP Tuners interface for WB is already on order. I just need to decide on which WB system to go with. I like the FJO since it will also interface with my N2O controller seamlessly, but it's a little steep. Another plus is that HP Tuners has native support for the FJO unit (also Dynojet and Innovate) so I don't have to worry about custom cals. The extra bung will find it's way into the big dog headers that followed me home the other day. ;) If you thought my car was already loud going down the track....

BTW I know this is off topic, but I'm looking forward to the auxiliary outputs from the new HPT cable. I think one will go to a shift light, and the other to a "lift off the throttle now or melt the motor" light.

John
 

·
Registered
Joined
·
1,224 Posts
That sounds like a good plan there john. Im excited to see and hear the new headers. The extra bung sounds like a good use for it.

Sounds like HPTuners is really working out well.

i do like the let off the gas or melt the motor light! :D
 

·
Registered
Joined
·
346 Posts
Discussion Starter · #11 ·
Arlee, yes it will but I meant that I already have the FJO nitrous controller. For me it would just be a matter of connecting matching connectors.
 

·
Registered
Joined
·
104 Posts
I have a dynojet wideband commander coming to my door next week, and I am curious as to what the HP tuners will be supporting wideband wise? I won't be fully ready to use this yet as I have to finish my fueling project yet, but I am curious as to what the pcm wideband support will allow us to do, will this allow the pcm to rely on the wideband sensor? Or will this just give us the scanning capability?
 

·
Registered
Joined
·
7 Posts
It will allow you to log the AFR from the wideband and directly match it to your VE table. So you will be able to pick the exact cells that need editing..
 

·
Registered
Joined
·
104 Posts
ataylors said:
It will allow you to log the AFR from the wideband and directly match it to your VE table. So you will be able to pick the exact cells that need editing..

With that in mind, I have noticed that with the pcm when I "tend to run leaner" (keeping in mind going off the general rule of the stock 02 sensor, what people feel is correct) I have noticed that I loose timing. I am able to run consistant 870 and lower o2 readings and recieve no knock but timing seems to dissapear no matter what I try to dial in via my happy knob (so I have dialed in my car richer now and I see the timing I am looking for). Now what I have been told is that in the pcm there is a "bad" and a "good" fueling table that the pcm goes off of and when it see's a "bad" fueling table it will pull timing. I am curious as to which if my stock 02 sensor tends to read lean but is actually in a rich condition is theyre a way to use the programmer to edit these tables so I do not have timing pulled if in reality I am running rich (which will be figured out via the wideband sensor once installed)?

I currently do not have a editor but may invest in the future into one, just trying to figure all of this out.
 

·
Registered
Joined
·
30 Posts
mcshocks said:
I have a dynojet wideband commander coming to my door next week, and I am curious as to what the HP tuners will be supporting wideband wise?
Right now, a lot of guys run the Bosch sensor from the LM2 and put the output signal into their AC pressure sensor. HPTuners already logs this pressure, you just have to convert it with an excel spreadsheet. If HP Tuners is putting it directly into their program, then that will even better.

-Geoff
 

·
Registered
Joined
·
30 Posts
mcshocks said:
Now what I have been told is that in the pcm there is a "bad" and a "good" fueling table that the pcm goes off of and when it see's a "bad" fueling table it will pull timing.
There is only one fueling table. There are two timing tables, and when your car gets a lot of knock, the PCM will interpolate between the two tables. There is also a third table (in the 04's at least) called "Max Torque Timing", and I still haven't figured out when that comes into play. Does anyone know?

-Geoff
 

·
Registered
Joined
·
346 Posts
Discussion Starter · #19 ·
I have a dynojet wideband commander coming to my door next week, and I am curious as to what the HP tuners will be supporting wideband wise?
I asked this same question a couple of weeks ago. V1.5 has native support for Innovate (LM1), Dynojet, and FJO. In other words you can just pick one of those from a list in the tool and it automatically uses the appropriate curve to translate the 0-5V analog input to an AFR. If you have a different WB, the tool also allows you to customize the tool to read whatever curve your particular WB controller puts out.

John
 

·
Registered
Joined
·
30 Posts
I just got 1.5 today. It has pretty much doubled the amount of tables, plus there is a huge section for PCM controls. A bunch of new idle stuff for all the cam guys too. I still haven't found the part with the wideband though. What is it under? Thanks.

-Geoff
 
1 - 20 of 24 Posts
Top