Closed Loop means that the ECU constantly uses values returned from the Lambda Sensors (two - one pre- and one post-CAT) to set AFR's. An N/A engine wants to achieve stoichiometric combustion - one where all the fuel in a charge is burned 100% by just-the-right-amount of air available - and this is generally accepted to be 14.7:1. A normally aspirated engine likes 14.7:1 overall and Closed Loop will broadly maintain this. It will richen up a little under full chuff (maybe down to 13.7:1), but that's about all.
There are 2 issues - one of which affects you and one me and others who think it was a great idea to supercharge or turbo the current FIRE engine....
Firstly, most remap techniques will rejig the map of fuelling and timing in an ECU to optimise things for improved performance. There's loads of safety margin built into standard maps in cars and these margins are exploited for both NA and Turbo motors. 90% of engine ECU's move from CLOSED to OPEN loop at about 50-60% throttle/load and start running on the inbuilt 3D map to ensure full control over AFR and timing - typically because ECUs couldn't react fast enough to the Lambda sensor signals to guarantee perfect mixture at really high revs and load. All well and good, as this exposed the 3D map during OPEN loop and every remap around exploited this. Rock and Roll.
But come the improved and faster ECU technology and CLOSED loop CAN be managed super-fast, hence the problem with the Bosch and Marelli systems in the Pandas. UNI-Q is a piggy back so it tries to interpret and then modify-on-the-fly the signals from various sensors to allow after-market optimisation of the parameters to improve performance. But Lambda is NOT one of those parameters typically, as it's never been necessary - until now. So what we now get is an ECU that will ONLY listen to the lambdas to set AFR and this is no good for aftermarket tuning or Forced Induction.....
Which is where I get screwed as I want about 12.7:1 AFR for my blown engine under high load and we had one hell of a job to get the thing into OPEN loop to prevent the ECU from constantly trying to correct things. We put in more fuel and the ECU backs it out again. We intercept the fuelling signals to increase the delivery and the ECU backs off the signals it sends from its settings as the lambdas are saying it's too rich. That's the nuisance!
We've had to do some dodgy wiring on my lambdas to get the ECU into limp-mode - at which point it has no choice but to run on the 3D map and go OPEN loop. Now that puppy is mine and the UNI-Q can do its stuff - 110bhp and 103torx in my case - but with the poxy EML light on all the time. It's still mapped to blow rose-smelling air out of the exhaust and runs CAT and everything - except it would fail an MoT if presented like that now. Reconnect the lambdas and out goes the light, but so does my AFR control at high load, so I don't ask for it.
I am looking into that fuel computer that was mentioned on here a while back that allows a full fat disguise of the lambda signals going back to the ECU, which means the ECU runs blind, but thinks it's got a nice 14.7:1 and is happy. We can then jig with fuelling and all should be good.
That's the theory - well you did ask! I have a lot of faith in Dastek and their UNI-Q and for your purposes they might be able to assist and indeed the unit you're looking to fit will be their latest and may have indeed cracked the issue. If so, then your input into this discussion will be vital!
Like I said, do report back and let us know how you get on. Good Luck
