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Discussion Starter · #1 ·
Rule #1 – Use a wideband O2 sensor.

Most people already understand why using the factory narrow-band O2 sensor is a poor way to tune a car:

http://www.3800tech.com/forum/showthread.php?t=848

For the 2004 model year, GM changed the O2 sensor and for us the problem has only worsened. On the dyno, we’ve run as lean as 17.0:1 and as rich as 11.0:1 for testing purposes. Take a look at some B1S1 readings when they’re layed out right beside wideband numbers.

17.0:1 – anywhere from 924 to 955 mV (too lean to make maximum power)
15.3:1 – anywhere from 956 to 978 mV (still dangerously lean)
13.5:1 – anywhere from 994 to 1007 mV (still way too lean in our view)
12.0:1 – anywhere from 990 to 1003 mV (our recommended target for the L32)

General consensus has evolved over the years, and many L67 customers tune their cars with target B1S1 values of ~ 940 mV with no intercooler, and ~ 910 mV with an intercooler. The bottom line is that if you use those same targets on your L32 you WILL break pistons.

In summary, use a wideband O2 sensor to tune your car. I just can’t stress this enough.
 

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What did the LTFTs look like when you had the o2s and the AF ratio where you wanted?


17.0:1 – anywhere from 924 to 955 mV (too lean to make maximum power)
15.3:1 – anywhere from 956 to 978 mV (still dangerously lean)
13.5:1 – anywhere from 994 to 1007 mV (still way too lean in our view)
12.0:1 – anywhere from 990 to 1003 mV (our recommended target for the L32)

So you do you think these numbers might have to be adjusted for climate and 91octane?
I am getting 910-920mv at WOT and if I set it around 990-1000mv I start collecting black soot quickly on my tips.

I guess until I have my OWN WB setup, I will have to decide what is worse collecting massive layers of carbon inside the engine or running too lean and cracking a piston? :(
 

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Does the L32pcm vent boost, and can that be controlled with some adjustments in the pcm?

What injectors were used on Rich's car?
 

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Discussion Starter · #8 ·
This data seems to directly conflict with INTENSE's IC car test data.

How is 17:1 possible with 920mvs?
Because of how non-linear the factory (narrow-band) O2 sensor is. See this thread for a better understanding:

http://www.3800tech.com/forum/showthread.php?t=848

Is it at all possible that Rich had a bad MAF? Afterall he saw numbers nobody else did by a few thousand HZ.
His numbers were that high with his stock MAF, and it was replaced with an 85 mm. unit.

What injectors were used on Rich's car?
Stock for the baseline, and 60 pounders for the post-intercooler tests.
 

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This post really scares me because people are going to think they can tune with their stock O2's. FWIW, my car has totaly different readings than these. at 920 it was 12.8 and 960 it was 10.7. In fact, I am pretty confident in saying that if you run 13.5 for very long you will be replacing pistons.

The bottom line is DON"T TUNE WITH THE STOCK SENSORS.

-Geoff
 

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Well your 12.8:1 @ 920mv @ 10.7:1 @ 960mv is much more inline with Charles Beyer's data presented on clubgp.

I can't wait to get some Wideband tuning done.
 

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I would highly doubt that 1000mv would be 12.0:1 and if you're tuning your PCMs to that you're most likely just dumping un needed fuel in. FWIW, I had a dyno run about a month back where my car was constantly registering 17:1 on the wideband. I know for a fact that 17:1 would last one or two passes before the motor breathed it's last breath. We spent about an hour doing this before I finally got fed up and had them change the tip on the wideband. In compensating for what we thought was a lean condition, I had actually made the car go pig rich, something like 10.x:1 when we got the wideband working correctly.

I'm not saying your findings are wrong, but I think that some more testing on different cars might net different results.

Bottom line is as mentioned above, don't tune off of narrowband 02's. :)
 
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