A narrow band 02's purpose is to simply monitor if the mixture is richer or leaner then 14.7 (think of it as an on/off switch it only has two states but ofcourse since it outputs a linear signal you will get all the noise inbetween while it constantly corrects (as stated earlier). A wideband however will provide you with a specifc value; typically from 9-16AFR (AEM). Some devices offer an even greater range, like 7.9-20.9AFR (Innovate Motorsports). The narrow-band simply does not offer the resolution required to safely tune your vehicle.

 

Yeah, on the dyno both times, I had the wideband hooked up for verification. If that wideband AFR was also wrong, then what can I say? The wideband AFRs were right in line with my o2 voltages. I had a mental correlation in my head before the dyno, and the AFRs on the dyno matched that expectation.

It's hard for me to say exactly what a .94v reading indicates, since my readings are all odd numbers (.91, .93, .95, etc), but I would say that .94 is on the rich side right around 11.0:1. When I had my car tuned on the dyno to 11.5 AFR across the board, I had .91 readings with one .93 at the top above 7000, which coincided with a dip in AFR down to nearly 11.0. This is why I recommend .92-.94 with an emphasis on .92v on 93oct. This puts you in the 11.3-11.5 range, even though 12.0 is still safe on 93oct. I don't push it to 12.0 on pump gas so that I maintain a safe margin in the case of a bad batch of gas or drastic change in weather (temp/humidity).

I don't know what you mean about the whole dynamic range thing. We've been tuning on narrowband for years and years with DSMs. Again, wideband is MUCH PREFERRED, but I don't have one yet.

 

We've been safely tuning on narrowband for years and years. The o2 voltages correlate to known AFR levels, and you can easily tune within those parameters with a logger. Again, watching the timing (knock) allows you to see if your AFR (o2) is off or too lean. EGTs add an additional parameter, just in case...

 

I respect the fact that you are making this work for you and that you are checking it against EGT etc. higher then nominal EGT ofcourse can indicate both an extreme rich or lean condition. They are also extremely slow respnose wise. None the less they are better then nothing. I guess your definition of safe and my definition of safe differ a bit. If the method is working for you keep it up I guess.

 

Here is my experiences on a 2g DSM a few years ago before I had an AEM. I would tune the car with a VPC and pocketlogger. I would see consistent .98v O2 readings on the pocketlogger which corresponded to 12.5-12.6 A/F readings on two different tail pipe sniffers on two different dynos. After that experience, I will never trust a narrowband again.

Take my expereince for what its worth.

 

I'm getting some good info here... right now my voltage goes to .94v across the entire RPM band. My timing is as high as 21 at about 7100 rpm, and I haven't seen a drop in timing at WOT what so ever which means I'm not getting any or very little knock.

Since I have my voltage linear across the whole RPM range would you say its better to start turning up my boost until I see a decrease in timing/knock or keep leaning it out?

 

I take it you were watching timing while tuning, so didn't you see an increase in knock or a decrease in timing? Did you still have a cat when the sniffers were used?

 

your best bet would be to somehow introduce a wideband into the mix to verify what your logs/narrow band are showing...I would do this before upping the boost at all. Borrow a friends, or do a few runs at a local dyno

 

I already have a LM-1 wideband unit, just at the moment its on another car that I'm tweaking with. But once I run a 12 second pass with just the AFC & K&N I will put an exhaust on the EVO and the WB will be installed also. Plus I don't feel like pulling the stock exhaust off and having a bung welded in only to have to pull it again when I install the new exhaust.

 

You're not seeing any knock, because you're still rich. The factory tune sees a timing advance to 20-21, but it isn't making as much power due to the very low AFR. I would lean out some more while making sure the timing does not suffer (still no knock). There is a delicate balance of boost, afr, and timing that must be established. You can hit your goal of 12s on the S-AFC with an 05, I'm sure. I did 12.8 at 106.3 with just the S-AFC, and I was still in mostly-rich territory with .95v across the board...

 

What I mean by "dynamic range" is the range of measurable AFRs. If you look at the chart I posted earlier it would lead you to believe that the only measurable range is between 14.25 and 15.5AFR. Also, it would appear that a voltage of .93-.95V says that your on the rich side of stoichiometric SOMEWHERE in the range of 10 to 14.25 AFR.

If I was tight for cash and needed accurate WBO2 readings, I'd buy the Innovative LC-1 ($200) and configure it such that one of the analog outputs is set up so that 1.00V=10.0AFR and 2.00V=20.0AFR. This way you can connect a digital voltmeter to the analog output and see your actual AFRs represented in real numbers. The other analog output can be left as configured by Innovative so that it can emulate the NBO2 sensor and keep the ECU happy and CEL-free. Down the road should you decide to add a dash display you can simply plug in the XD-1.

 

The timing maps on a 2g DSM are similar to the EVO. (Big midrange dip followed by a gradual increase up to redline (assuming no knock)). There were no timing dips after peak torque and the car made around 395whp back then. There was no cat on the car.

 

Well I have an 04 but I still think I can get that cause I went 13.3 @ 106 with just a MBC and that was having trouble getting 3rd and my cousin went 13.1 @ 104 on a 1.9 60' his first pass so I car should get there. If I can drive it correctly is another story.

Back to the tuning, my factory map only peaked to 15-16 deg at 7200 and that was with .98v readings on the O2's. My current tune I peak at 21 and boost is only at 1.3bar (peaking at 1.4 for a split second) but you think I should still lean it out more.

 

Well, you didn't mention an MBC. You just said an S-AFC and K&N, so that was different. Most 05s don't even hit 106mph with just an MBC, so your car must be extremely strong. I only hit 106 with exhaust, mbc, s-afc, bov, K&n, although it was on a 12.64, so you must have an extremely strong car, unless those runs were done in the cold of winter or something. Even then, it's far stronger than most 03/04s, so that's good...

I don't know why you only peaked at 15-16...mine peaked at 19-20 just like it was supposed to. I don't think you should lean it out a lot, but if you pull out 1-2% from 4000-7500, you would probably see more .92s and have the same timing....

 

You may as well be picking numbers out of a hat if you are tuning off the narrowband o2 numbers.