rsilver

I have seen this issue brought up in other threads but have never read an explanation. I also touched on this in my thread "why use winald if you have a WB02."

Anyway, in tuning for my new 90# injectors I am getting BLM's in the 108 to 120 range when my WB02 says i am running an AFR of 16+. This is at part throttle cruise. Almost all the cells in winaldl are below 120 yet my LM-1 data logger shows I am in the 16 to 17 AFR range for like map and rpm's .If I take out fuel, per the BLM's in WINALDL, then my AFR gets even leaner.

I reduced my BPW to get rid of rich condition at idle because I could not take out enough fuel in table one (8746 ECM) to get rid of rich condition. So my idle is ok with BLM's around 123 and AFR in the low 14 range.

I had to add a lot of fuel to table one for WOT given the reduction in BPW but I am getting in the 12.5 afr range. WOT performance is very impressive SOP.(Wish I had gone to bigger injectors a long time ago) This car has the opportunity to be respectible now.

My narrow band o2 sensor seems to be working at least it is switching back and forth from .1 to .9 VOlTS, although not very fast.
Calibration of WB02 is per instructions

Should I Ignore the BLM's?

Why is there a descrepency?

Could there be something wrong with my narrow band o2 sensor?

Hope this makes sense and that you guys will take a look at this and give me your thoughts.

thanks very much............bob

HaulnA$$

Did you disable highway mode? Are you using a heated NB O2 sensor? Where is it located in the exhaust? Both of these factors affect how the sensor behaves. The further away from the engine the sensor is, the greater the need for a heated unit. You may have to play with your rich lean O2 voltage thresholds. HTH

rsilver

Yes I disabeled it for cruise. I am not using a heated sensor but it has never given me a problem in the stock location in the slp headers which put it very close to the block.

I am thinking that the 02 switch is bad.

any other ideas??

Thanks..............bob

rsilver

I replaced the nbo2 sensor, recalabrated my lm-1 and I still get blm's in the 110 range while wbo2 says I am anywhere from 15 to 16 afr. I don't get it.
I even got out my old scan tool and checked blms there and it says the same thing. Does changing PW change ECM data output??

right now, the only thing I can do is log afr vs rpm vs map and do the best I can.

Any one else got and Idea? Hope grumpy or rbob can comment..........thanks...........bob

novass

iTrader: (1)

I was running into the EXACT same problem. The NB was causing the car to run lean 15-16 shown on the WB. I went to total OL and never looked back.

I messed with trying to change the O2 swing points, however, the problem I had with that was in the lower RPM's at a given MAP reading it was right on 128 at about 3000-4500 it went lean at the same MAP area, so changing the swing points would then cause a problem down low if it improved it up high. So... I went OL and have been very happy.

I tuned the VE tables using the WB to 14.7'ish and the car ran better than it ever did. In PE I shot for 12.7-13.1 range and what I believe are good results (I used Traxons VE tuner, made things easy for PE tuning)

I still have a bit more work to do on light cruse to lean it out a bit to get the MPH up a bit more, but not a biggie. I was getting 23-24 with the previous tuning on the HWY using HWY mode. With OL and WB tuning I am now at 20, however, Like I said above my light load is set at 14.7, I haven't had a chance to lean it out yet.

If you do come up with a magic way to get the NB to act nice and agree with the WB please let me know. I have nothing against CL, just that with the WB tuning and OL the car likes it.

Here is my post on the topic my link

Low C1500

Are you running 747? or 746?

There are tables that have O2 toggle points. Usually there in the 430mv range. Increase these tables, and you decrease your AFR.

Its been said many times before, that GM made some calibrations a little lean to meat emissions.

Also a BLM of 115 doesn't mean a rich condition, it just means that a VE cell is out, and the ECM is corrrecting for to maintain stioch.

rsilver

thanks guys. I am reluctant to go OL only right now. I tried it once and didn't notice much improvement. My mileage has been 24 to 26 on long trips @80mph and i would like to hang on to that if possible and am not good enough at tuning to get it with OL only yet.

I read a comment made by rbob or grumpy I think that said there were tables in the various ECM's for BPW in additon to the main constants section so I changed my BPW CONSTANT VS VACUUM( EGR ON) table to be consistent with the change I made in the main BPW constant and the computer likes it a lot better. Where I was at 108/110 BLM I am now showing 124 to 126 with out any other changes.
Still, my WB shows lean even though these revised BLM's indicate slightly rich, but that could be due to slow 8746 ECM OR?

In the end I still wonder if aldl data logging fuel for purposes of tuning fuel table is meaningful. Maybe for stock bins, I don't know.
If I am wrong on this, let me know what else I have to change to make my BLM's more meaningful for purposes of part throttle tuning.
Hey, when I started this, the store bought WBO2 was just a gleam in someones eye!!!

Of course I would love other comments and help understanding what bpw vs vaccum table really does but I know everyone is busy..

Additional comments appreciated if you can.........thanks......bob