After having failed the CT dyno emmissions test three times, it appears that I am still WAY lean.

I am now running the Wett K04 (v4.0) chip with a 5 bar fpr. Although this chip is only a 13-14lb chip, the car feels faster than it ever has and my NOXs are down from 1500ppm to 800ppm. This tells me that I am closer to stoich than I have been in the past. The dimmer glow of the turbo and lower oil temps also tell me that my part throttle mix is better too.

My epiphany came when I got the VAG-COM hooked up. Under block 031 I can see the pre-cat O2S reading. The pre-cat O2S readings of .69 volts to .73 volts at 3500 rpms WOT and that migrates to around .820 at 4700 to .800 at 6700-7000. My interpretation is that anything below .850 is too lean for the turbo motor. Any thoughts?

Anyway, I am going to put in either 27lb or 32lb Bosch injectors and need help interpreting so I can dial the programming in.

Mike O.

 

I thought it would be 1000ppm. I remember your previous posting which shows your CO's to be ok, but your NOX pretty high, and a few of us suggested the catalytic.

Anyway, I wouldn't trust a stock O2 sensor reading at anything past cruising throttle. They do not react that fast. Then again if they don't then maybe it is showing a more conservative value at 0.8V, and maybe could be higher.

But at 3500 WOT, I don't know what gear you are in though and how long you stayed at that RPM, 0.6-0.7 sounds OK. But I recommend a 4th gear uphill pull at WOT, observe the boost and duty cycle, probably a better indicator. The O2 sensors may also show a different reading.

For fuel injectors, what are stock ones? I thought they were 240cc's (about 23 lbs). Anyway, if they are 240cc's, and if I use that for stoich, then a 27lbs will take you to about 12:1 and a 32lb will take you about 10:1 - with stock injector programming of course - I'm assuming the Wett did that. Do you know what your MAS indicates at cruising (emission test, minimum turbo boost) throttle and at WOT?

And you know what might help in this case? Some Toluene. Ok, I don't want to start that long discussion below, but I notice the octane boost richens up my setup an "LED" on my air/fuel monitor at WOT Well, back to regular everyday driving pump gas now, so that LED doesn't come on again

Good Luck, just trying to help and understand for myself

 

I don't know if i get that right, but Lamda 1 is ideal for a non turbo and Lamda 0,8 is ok for a turbo. As far as I know Lamda 0,8 is richer than 0,85 or 0,9. Maybe we speak of two different things.
Ralph

 

Ok, you've got the VAG-Tool and that's great! You'll be able to datalog, you just need to know how to interpret the results.

If you see 1.0 on the O2 readings, that's 14.7, which is stoich. If you see readings over 1, then you're over stoich, which is lean. Readings under 1 are below 14.7, which is rich.

In other words, you're NOT running lean!! In fact, your air/fuel looks to be just about right.

Most of the time if your NOx is really high, that means your cat is failing...

 

No- .9 is about right... over that is rich and under that is lean.

 

number differently. It is normal for the precat O2 sensors to cycle from 0.2 to 0.8 volts during idle and cruise. Post cat at steady 0.4v

 

yes, you are, read my post to Doc Wyte.

 

0.87 is exactly right. Under that it's lean, over that it's rich. It's better to run rich than lean. At WOT you should see between .87V and .9V throughout the RPM range. If you have some RPM where it drops just slightly to .85, then that's OK, as long as you're at or above .87 through most of the RPM range.