mysterious fat afr on wot

Jona$

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Snowmobile
Tapex/sks 800 -16
At 10500rpm the sled gives out 10.5afr

This is what i have tried to get it working

*pressuretested inlet and outlet, fine.
*checked all wires with multimeter, fine.
*sent the efi from mcx for test and was fine, got the brown bosch injector and corresponding map, sled acts better but still low afr.
*did a compression test and got 9.5 at all exept cyl3 giving 0.3 lower, so fine
*Tested the afr sensor and it works so i trust the numbers.
*The fuel pressure seem to get to about 4bar on full boost and around 2.5~2.9

The sled works flawless in all ways and i can really feel it but the afr dont lie
 
I just can t figure it out.
There must be anyone here with some idees
 
Fuel has a big influence. My AFR at WOT changes when I switch fuels...
The fuel map is gonna be set richer to account for oxygenated fuel so you get 11.5:1, so if you are running an non-oxygenated fuel or a race fuel that has a higher specific gravity (denser) then your AFR will be richer at WOT accordingly.
 
vmax4ever said:
At 10500rpm the sled gives out 10.5afr

The sled works flawless in all ways and i can really feel it but the afr dont lie[/quote

I had a similar event but with carbs... WOT 10500 reading 10.0 ... My cure came from
Jetting down from 135 to 130. Not sure how that translates to FI.
 
I run pumpgas set at 95-98octan RON, allways gave me over 11 in wot.

i also checked the wastegate and it opens at 0.8bar.

it feels as i looked at everything now, but obvious something is making it go fat in some ways.
 
Come on people, is there any orginal sensor here that could throw something wrong?

I called Eric to be sure it still cant be the Efi mcx, and he says its a small chance he could missed something but dont believe it.

He also told me to check that the throttle bodys hasnt come off, but my boost test gave no leaks.
He also told me to check the charge tube between intercool and precooler hasnt got flat, but im not buying that one..or could i be wrong?
 


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