I am installing a cam soon, and am thinking about just picking up HPTuners instead of getting it tuned by someone in the hopes that I can get a better tune going. Problem is I don't have enough money left for both the software and a wideband...is it possible to tune without the wideband for a little, at least to get the tune baselined? Or am I going to have to get it hooked up to a wideband at some point no matter what?

 

https://ls1tech.com/forums/pcm-diagnostics-tuning/680221-tuning-using-ltft.html

 

Yes, you can get pretty close using the narrowbands. Not as
easy or straightforward. I would not use the trims because
they accumulate results from too broad a range of conditions.
But using the NBO2 voltage as your guide and maintaining a
1.000 EQ (target) you can iterate your way to a pretty clean
VE table and true up the MAF somewhat. The only place you
have to worry about is high MAP and you can kind of wing it,
there, if you can get the RPM axis done.

I did it this way before I had a wideband. You do a lot of driving
on a "special" tune with the engine forced open loop and the
spark advance reduced enough to not hurt you. You log the
O2 voltages, RPM and MAP. Do some 1/8, 1/4, 1/2-throttle
acceleration pulls. WOT if you can pull enough spark out.

Then you crunch the data by hand (eye). Follow the RPM and MAP
and where they point on the VE table, you do something like

O2 V < 200mV multiply VE value by 1.1
200mV < O2 V < 300mV multiply by 1.05
300mV < O2 V < 700mV do nothing
700mV < O2 V < 800mV multiply by 0.95
800mV < O2 V multiply by 0.9

Tedious for sure, but you can get there and it will shape
up quick after the first couple of passes. Eventually it
will all be "do nothing". Then you're done (with that).

What this won't do, is determine for you the right WOT
fueling target and whether you hit that as cleanly as you
hit 1.000. But you can get pretty close, and call it good.

Do it this way once and the wideband will look to be worth
every penny....

 

I actually prefer using trims to clean up part throttle. It takes a bit longer because you ahve to wait between relearns but the results are always pretty good. I would be very careful attempting wot tunign with the stock narrow bands. For naturally asperated setups I usually try to shoot for a 900mv if I don't have my wideband. For beginners I would definately try to get one.

 

I have found fairly accurate readings by using the Ltrims, But the method I found to be most usefull is accelerating to wot in say 3rd gear where the rpm ramp up time is slow and sufficient enough to (try) and get a steady reading since the O2's are exactly what they mean a Narrow Band, on A4's I do the same trying not to let the tranny downshift. I have done this and then customers have gone to dynos for pulls with a wideband and the A/F have been very accurate across the board...

 

Applying a little left-foot brake during the pull will help slow down the ramp rate of 3rd gear too.

 

Jimmy:

Have you compared your O2 method to using STRIMs to see if there is that much variation? 2 or 3 iterations on STRIMs gets pretty stable when you allow for +/- 3% variation.

 

thanks for all the information guys!

 

I've never compared methods, but find my trims are
pretty stable. The STFT (+LTFT or LTFT=0) method
still has some of the same granularity problem unless
you can spend a fair time at the same load-point to
"bury" the transitional "tails".

I think you'll get to the right answer either way, and
histogramming it in either case can shave a lot of time
vs manually picking points off a sorted Excel dump.

 

I set the LTRIMs to zero to log. When I'm logging I try to deliberately hit the points that are data points on for the table. So I'll try to hold 1200 rpm and 1600 rpm in various gears and various throtttle loads for a while then try for the 2000 and 2400 rpm and finally 2800 and 3200 rpm. Kinda of POA on the street if it is crowded.

 

I have has sucess in the past tuning part throttle areas by the LTFT's but for a good WOT tune you will want a wideband.

 

A few things to think about:

- you can buy a good wideband for less than $200
- tuning with trims will take more time, VE and MAF tuning with a wideband can be done in one day
- the fuel you will save using a wideband over LTFTs would probably pay for the wideband
- you cannot tune wide open throttle without a wideband, your narrowbands are not accurate enough
- the peace of mind knowing it is exactly what it should be