MFI thermostat / enrichment

[hot66]

MFI experts …..

I’m trying to get to the bottom of an issue with my 2.4S , its all is set up really well and drives great at normal road temps ( 80deg engine temp) and the afr’s are good too with hard acceleration at 7000rpm in 3rd afr is about 13.5

What I’ve found though is after some real hard driving , and the temp gauge reading 90deg + the mixture is leaning out right at the top end and showing about 14.2-14.4 afr at 7000+rpm

I gradually went 6 clicks rich on the main rack and Ive brought those top end afrs back into the 13’s but when back at normal road engine temp I feel the car is just a bit too rich which o know for experience can lead to oil dilution.

On the back of the above, when the engine was ‘road temp’ I pulled off the triangular top cover on the mfi pump for the the thermostat lever and and found I could move it still maybe 3-4mm until it bottoms out

The thermostat rod, discs and spring are all clean and correct. I’m assuming at normal road temps they are only closing the cold enrichment off so far and when at 90deg + the rod is extending that little bit further and Leaning it out. In this case The mfi has been tuned based on normal engine temp

Anyone know if the enrichment lever within the mfi pump should be pushed as far as it can go by the thermo rod ? Or should there be a little bit of movement before it bottoms out ?

[hot66]

Pic showing how much more potential the rod could move