Turning off PE...wideband accuracy???

[hquick]

What do you all think of this posted on another forum by a well respected 'Pro' tuner?

Dont waste your time. Use fuel trims.

If you insist on using your wide band for part throttle and idle (you will be very lucky if your fuel trims agree with your wide band) at least turn off the air/fuel ratio toggling the PCM does most all the time.

To shut that off, set the P.E. minimum temps and RPM to zero, P.E. enable throttle angle to all zeros, and the P.E. vs RPM Air/Fuel multiplier table to all "1"s and the P.E. vs temp table to all zeros. Otherwise your wide band is likely going to be showing you junk numbers, which may or may not be even close to correct. Even then, many of the popular (on internet message boards, at least) wide bands vary widely. Several require calibration, which from the ones that have come through my place on customer's vehicles give numbers that are all over the place. The wide band on m dyno, several of my customer-shops dynos, a stand-alone Dynojet unit I used to use in my race car with the factory PCM, my first stand-alone from Austrailia (forget the brand name) and the one used by the FAST ECU now in my race car all are together, the ones many customers have in their cars hardly ever agree. Some indicate much richer, many leaner. Personally, if I were going to buy one it would have to be from Dynojet or FAST.

You would be better off using fuel trims. Wide bands (Accurate ones that is) are only for WOT tuning.

If you set the P.E. like I listed you may very well find it is not lean where it now shows it to be lean. All the wide band mfgrs make claims about their product's accuracy (lab grade, etc.), they are also in sales after all. There is more to it than resistors, there is the temp control and monitoring unit, also the software. I've never heard of your brand, but it may be great. Bosch makes a good sensor. That is what Dynojet uses.

Are you going to leave your vehicle in open loop all the time? If not, as I said before, your wasting your time. The PCM is still going to try to correct it. I'm betting you will eventually find your not lean where you now think you are. Rich will make one "bog down" the same as lean. Bogus lean numbers is what you will see at idle and part throttle, never bogus rich. Less than half the vehicles I have tested over the years will show 14.7-1 air/fuel at idle and part throttle with a wide band. That is unless you set the P.E. parameters as I outlined earlier. That is due to the wide band trying deal with the rich/lean toggling I have tried (evidently with very little success) to explain several times before. See if you have some black on your spark plugs. The PCM won't toggle the fuel rich, lean, rich, lean in P.E. mode. It does that pretty much all the time otherwise. It does that to store oxygen in the cats. Even if you turn C.O.T. protection off, it still does that. If you want your wide band to be correct (assuming it is), put it in full time P.E. mode while you are trying to do your V.E. tables. When you re finished, and put it back into closed loop, you may very well find (as many others have) that your fuel trims are again whacked. Many guys are trying to tune these like you would a FAST, Bigstuff3, DFI, etc. Those don't toggle the air fuel up and down like a factory PCM. They aren't as complex as factory computers, and aren't intended for vehicles with cats.

If your vehicle won't run correctly with the fuel trims corrected, your just adding fuel to try to cover up another problem. Very common mistake.

[macca_779]

I reckon this guy has never seen COS 5. He's making stuff very complicated that really isn't.

[hquick]

I'm kinda in limbo Macca.
I see alot of info on here from guys that have never tuned the 'trucks'...and the trucks seem to be somewhat of a paradox for many who haven't 'played' with them.
Now...today...after finally getting my RR running properly, it seems it may have been the cause of my screwy AFR #'s.
Feel like I'm back to scratch...again.
Now just trying to workout which road to take....again!!!

[Delco]

I reckon this guy has never seen COS 5. He's making stuff very complicated that really isn't.

And why would you trust a narrow band O2 that can be out quite a bit at closed loop.

like any tool a wideband needs to be calibrated , and checked against a proper high quality unit.

All too often I see guys using a cheap wideband , then pluging it into a cig loghter socket and then expect to get reliable consistant results. 9 cog loghter would have to be ne of the worst power sources for earth drop of any system around )

A direct wired wideband to the battery for power and earth , calibrated pid to reflect the drift your wideband may have and then tune to what the car wants not a number and you will never have a problem.

Too many people tune to a number and never get the car on a proper dyno to learn that the engine wants different AFR's at different RPM and load to maintain complete combustion effectively and they can be very sensitive to a couple of degrees timing change - all things that are very hard to do on the road.

[Gelf VXR]

My knowledge is limited however, but I do calibrate my WB before every log.

I fail to understand how WB can only be trusted for WOT and not part throttle. It measures oxygen in the exhaust gas, its function remains the same no matter what the engine state??

If its out at part throttle, its out at WOT

He states

"That is due to the wide band trying deal with the rich/lean toggling"

I'm confused why he says the WB toggles the fuel rich, lean ,rich ,lean unless in PE mode??

What he is describing is closed loop fueling, NB STFT switching is it not??

From my experience on forums, the people in the know usually give short concise responses, people who think they know long BS explanations that don't make any sense, I know what I think of this response



I don't think he has grasped the whole concept of closed and open loop fueling and has them mixed up

[Delco]

My knowledge is limited however, but I do calibrate my WB before every log.

I fail to understand how WB can only be trusted for WOT and not part throttle. It measures oxygen in the exhaust gas, its function remains the same no matter what the engine state??

If its out at part throttle, its out at WOT

He states

"That is due to the wide band trying deal with the rich/lean toggling"

I'm confused why he says the WB toggles the fuel rich, lean ,rich ,lean unless in PE mode??

What he is describing is closed loop fueling, NB STFT switching is it not??

From my experience on forums, the people in the know usually give short concise responses, people who think they know long BS explanations that don't make any sense, I know what I think of this response



I don't think he has grasped the whole concept of closed and open loop fueling and has them mixed up

Gotta agree - self proclaimed po tuner he is not.

When I say calibrate wideband I mean calibrate the pid voltage function against a know high end wideband or a gas chamber so that what the wideband reads in EFILIVE is the actual AFR reading , the sub $1000 widebands are average

[hquick]

Thanks for your opinions guys.
Believe it or not...the guy IS a very well respected professional tuner who has tuned hundreds of cars.
I guess that's the downside of forums and tuning though...some people are set into tuning in a particular way with a particular software...and others do it another way with a different software.
For 'plebs' such as myself....it becomes very difficult to differentiate sometimes.

[hquick]

This was the last reply I got.


Originally Posted by hquick
What do you recommend if staying in OLSD?
I'm going to try what you suggested about enabling the PE full time just to see what you're explaining.
Thanks for the information/lesson.

I *DON'T* recomend staying in OLSD! If your hung up on using your wide band for the VE tables (which I have tried to stress is just flat wrong) that mode would be the closest your wide band will come to being correct at idle or part throttle. That is how you tune a DFI, Big Stuff 3, FAST, etc. Those boxes do not toggle the air/fuel all the time rich/lean the way a factory ECM/PCM does (Except for PE & DFCO modes.). As I have said many times, I would ignore advice from anybody that tries to tell you to tune a GM computer that way. It's just wrong. They need to take some classes. They have a LOT to learn. No "custom OS" I have seen so far (and I have looked at several) stop that function either. This is the last I have to say on this subject.

What can you tell me about what was written above Delco? I believe you have an inside/indepth knowledge of OEM PCM tuning/functions?

[dc_justin]

This was the last reply I got.


Originally Posted by hquick
What do you recommend if staying in OLSD?
I'm going to try what you suggested about enabling the PE full time just to see what you're explaining.
Thanks for the information/lesson.



What can you tell me about what was written above Delco? I believe you have an inside/indepth knowledge of OEM PCM tuning/functions?

Remarkable...

[Delco]

This was the last reply I got.


Originally Posted by hquick
What do you recommend if staying in OLSD?
I'm going to try what you suggested about enabling the PE full time just to see what you're explaining.
Thanks for the information/lesson.



What can you tell me about what was written above Delco? I believe you have an inside/indepth knowledge of OEM PCM tuning/functions?

Sound like the guru is trying to tune while still running closed loop which will never work , turn off closed loop then tune the VE table properly , then if you desire turn closed loop back on and compare your wideband to your narrow band.

he is correct that when in closed loop the pcm adds and subtracts msall amounts of fuel to keep the o2 toggling about the setpoint - this is why you can achieve better emmisons and fuel economy ( takes intense tuning and continual updating as the engine wears and the reason why the OEM use closed loop to maintain the mixtures within a know band ) in open loop if you spend the time.

When tuning OEM we always tune in open loop then activate closed loop once the base tune is done , then we tuned the closed loop system to maintain the control we desired.