UCON Flex Advanced Engine Management System

Mine has always been stoich at cruise.

 

I guess thats why tacos get such shit fuel economy lol. My S4 was around 18:1 at cruise.

 

Lean is where it's at, thats why my diesel jetta got 40mpg at 80mph lol. Of course diesel is a whole other game.

 

Yes it is, gasoline engines (not lean burn engines) are meant to run at lambda 1 (14.7:1).

 

At high load I agree, you want stoich or richer to be safe. If you're cruising lean is what most cars shoot for. Better for emissions, better fuel economy. Even my bike runs north of 16:1 when I'm just maintaining speed on the highway. As soon as you crack the throttle it richens up but 14:1 cruise is just wasting fuel on a modern engine.

 

Yeah, if you're catless maybe. 14.7 or a tad under is ideal for catalyst efficiency.

 

Try that on your 1GR. Tell us how that works out.

 

I will make on offer on said engine if you do try it

 

More notes after observing the wideband behavior.

You have to drive on a figurative egg shell to keep the system from enrichening. As soon as it hits 0psi the AFR dives to 12-13. It will stay there even if you use less throttle and go back to vacuum. You pretty much have to close the throttle to get it to go back to the 14s. It's not a smooth enrichment ramp, more like a dump valve on tip-in.

Calling on full power the AFR will dive to 10.5, then wobble around 11.

 

@Voodoo Rufus what size pulley are you running?

 

2.85". Nothing crazy. I did do the fuel pressure reference to boost mod, though. It helped but did not solve my top gear roll on knock.

 

Gadget says not to do this with the ucon.

 

Interesting. I can try switching it back and see how it behaves.

 

http://www.xr-underground.com/threads/boost-referencing-video.58540/

 

Well then. Off the mod comes tonight!

 

Mine dives to 12-13 under moderate throttle, 10-10.5 with heavy throttle. Goes rapidly back to 14s when I stop accelerating & just maintain speed, even at 85mph.

 

Going to swap back the FPR mod, and maybe give it a good run this weekend.

Starting to wonder if my 4 mile commute and the rich-happy tune has been the downfall of my plugs and cylinders. Might need a good freeway run and "italian tune up" to blow the carbon out periodically.

 

Mine gets the Italian tuneup daily!

 

Gave it a good run this weekend. 16mpg average. Max boost AFR is 10.5. Tip-in AFRs 12-13. It doesn't like to return to the 14s until vacuum exceeds -5 inHg. No wonder it guzzles fuel on slight inclines in top gear. I have to proactively downshift it on a hill. If say going over an overpass and it boosts up and stays rich, a click down on the cruise will get it to go back to stoich. Then back up to get the speed back. If the system does go back on it's own from rich to stoich, there's a momentary loss of power. I've noticed it before, but now I see it does it on the AFR change, not just out of the blue.

Seems like it's doing what it's programmed to do. I guess you could call it "performance oriented", but for daily use trying to maximize mileage it is not ideal, yet. It's interesting to learn how this thing behaves and operates.