hquick
August 16th, 2008, 11:01 PM
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.
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.