[Gregski]

Just wanted to clarify something that had me tripped up for a while and may help you. The objective is to get us thinking, in a non biased way as realists.

Do you need a Wideband Oxygen Sensor AFR Gauge to tune?

The short answer is no. The better answer is, it depends.

I bring this up for two reasons:

1. We need to understand what is controlling what as the vehicle goes through it's operational phases in order to determine for ourselves which tuning method to use and why.

2. There are many articles written on how to tune and especially many YouTube videos out there as well that do not clearly state in their title / subject which method they are using, and a beginner can spend a lot of time pulling their hair out trying to figure out why the methods differ.

Let me preface what I am about to say and tell you that I am not anti Wideband gauges I use them I run them in my vehicles, however there are Pros and Cons to using both methods.

Tuning Using the Stock Narrow Band Oxygen Sensors

PROS

• no additional costs, you already own these sensors
• in the end the PCM relies on and uses these sensors to operate, not the Wideband (think about that for a minute) this argument gets lost quite often in the debate

CONS

• can't tune Open Loop state with them such as WOT
• can't see actual ratio values in quantitative terms, ie 12.5 AFR or 15.9 AFR

You can tune 90% of your naturally aspirated engine using the narrow band method. The only thing you can't tune using the Narrow Band O2s is Wide Open Throttle aka WOT. Why did I say 90% because when it comes to street cars, our daily drivers think about it, how much time do you spend flooring it? Be honest with yourself, you probably rarely gun it with the pedal to the floor, right?

Think of the engine operation as an Oreo Cookie, the black parts being something called Open Loop and the white middle being Closed Loop. When you first start your car it is running in Open Loop, then once it warms up it enters Closed Loop (idle & cruise), then when you floor the gas pedal aka WOT you are once again in Open Loop (the other side of the cookie). In Open Loop the PCM is not relying on the stock narrow band O2 sensors, it is simply not listening to them. That is why you can not tune WOT with narrow band oxygen sensors.

Tuning Using Wideband Oxygen Sensor(s) AFR Gauge

PROS

• able to tune entire operation spectrum (idle, cruising, WOT, etc.)
• read actual ratio values in quantitative terms, ie 12.5 AFR or 15.9 AFR

CONS

• additional costs (parts and installation, bung welding, etc.)
• vehicle does not operate using Wideband sensors for input, calibration differences could impact final results
• often times Wideband is a temporary install and not permanent
• Wideband placement during tuning
• technically you are always tuning in Open Loop

It is no secret that the placement of the oxygen sensor can yeild different readings. Put it too close to the collector you get one value, put it too far past the collector you may get a different value, hewk just shove it in the tailpipe you can get yet a different reading. A lot of tuners will remove a narrow band sensor and screw in a wideband in it's place, the problem with that is, it is temporary and only tells you what you got while you are on the dyno during that hour session.

I used to play Water Polo, and our team was pretty darn good. Most of our time was spent in the pool playing [ahem] Water Polo. Folks would often times wonder what made our team so good or what was the secret that our coach had, and it was that we did not do drills, we did not lift weights, we did not run laps or stairs, we just played Water Polo. We played a lot of gosh darn Water Polo, ha ha.

I like to street tune my vehicles, because I drive them on the street and not on the dyno, ha ha. When I log my data I like to log it while driving to work or log it while driving back from work, more than taking the vehicle for a random test run down roads I will seldom or never take. In other words tune for the conditions you will face not well you get the idea...

Don't get me wrong there are good dyno tuners out there, but I hope I am getting the concept through. Getting your vehicle tuned for two hours on a sunny day on Saturday morning in a guys shop with a huge fan blowing on the front grill to keep it cool with a Wideband AFR gauge shoved into the tailpipe on a two foot long stick may not exactly precisely represent the driving conditions you face on a daily basis (cold mornings, scorching hot afternoons, rain/humidity), are there any hill climbs, how about descents, etc. How about bumper to bumper rush hour traffic?

... and please don't get me started on Mail Order PCM tunes!!! hee hee

RECOMMENDATION: In the end I like to use both methods, aka the belt and suspenders solution, that way you can cross check your results and perhaps account for any discrepencies.