308 GTSi 2V exhaust gas CO content

See Chart Below and I did a comparison of E-10 and non oxy gas
http://www.ferrarichat.com/forum/showthread.php?t=361404
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Not sure about 2V but, when I had my QV smog two years ago, this is the result I got.
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You have to be more specific about where/how it is hooked up -- i.e., the CO/HC data in MNE's post are the factory recommended adjustment targets measured upstream of the cats with the air injection disabled (which is how it should be done by the mechanic making the adjustment on a US i-2V). The data that Mike posted is measured at the tailpipes so is after treatment by a working cat (and are much lower values, but a US i-2V with good cats and a working air injection system would be in the same ballpark at the tailpipes).

 

This is a good question. I have a euro QV, and when I set my CO at idle per the manual I find that the car is pretty lean on the dyno. Anyone know the right answer here? Follow factory idles specs, or adjust AFR under power on the dyno?

 

I think you are right that the factory specs are towards the lean side at idle (so missing a bit past the high end spec isn't uncommon ), but, even if you add some richness at idle, it doesn't add richness proportionally with RPM. What you really want is a different shaped "funnel" in the airflow metering device that would give extra deflection to the central plunger in the fuel distributor that did increase proportionally with RPM.

 

Not proportional, but it should shift the curve up and down.

If I adjust richer at idle, it will also be richer at higher RPM.

 

The "shift" in the A/F curve will not be the same vs RPM. Yes, it will be significantly richer at idle, but only a very small amount richer at higher RPM -- if you add 10% more fuel at idle (1000 RPM), the A/F ratio would drop from 14.7 to something like 13.4, but, at 6000 RPM, the A/F ratio would only change from 14.7 to 14.5 (because the amount of added fuel is still the same small value; whereas, you would want it to be 6X that value at 6X the RPM).

 

Exactly....

 

Agreed. I never did the calc myself, but that does make sense. Ok, so the next question is what is the maximum safe AFR for our cars under load?

 

Under really heavy load (i.e., low manifold vacuum), the WUR should be dropping the control pressure and adding some extra enrichment. I don't have a specific limit in mind, but do you have some dyno data to share?

If you did adjust to add enough enrichment to be significant at high RPM, it would probably not run at idle.

 

Dyno data here:
http://www.ferrarichat.com/forum/showpost.php?p=141447536&postcount=17

First two pulls were either quite lean, or the AFR was not reading correctly. After the first two I adjusted the idle mixture screw 1/4 turn richer for the 3rd and final pull (the red line on the plot).

This was from a dyno day I signed up for (3 pulls for $50 or whatever), so I didn't get a chance to do any additional fiddling.

 

Yes, I'd have to be skeptical of that AFR data for three reasons:

1. The variation (or lack of it ) for the first two runs just seem too small. The third run looks like a much more believeable sort of variation;

2. Taylor (an ICE ref book) gives that changing the AFR from ~14.7 to 13~13.5 should raise the bmep by a couple~few percent. Since all of your runs are right on top of each other, doesn't seem like there was a real change in AFR (i.e., on that scale, even a ~1% change in torque would show on that plot); and

3. as mentioned before, tweaking the mixture screw should produce more of an AFR change at the low end than at the high end which seems reversed for runs 1&2 vs run 3.

A 1/4 turn on the mixture screw is a huge change -- did the car idle OKish at that setting?