Technical Panda 1.2 Marelli ECU - what makes it go Open Loop?

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Sorry for the cross post, but I need to find an answer to this quickly if possible!


Getting desperate now in trying to get the UNI-Q mapped to the OEM ECU, following installation of the Rotrex Supercharger. I know that not everyone likes the Dastek UNI-Q, but I am where I am at present, but I have a simple problem.

Despite having the ability to change fuelling and timing for the map held within the ECU, this is only any good when the car is running Open Loop, instead of Closed Loop (closed being via feedback from the Lambda sensors etc). Typically you'd expect Open Loop from say 60% throttle onwards and/or approaching Atmospheric on the MAP. We've clamped MAP output to 4.75v (atmos being 4.8v ordinarily), but regardless of the bosst, % throttle or load, it won't go Open.

Only time Open Loop engages is on closed-throttle coastdown. In Closed Loop it is constantly trying to set AFRs in the 13.5-14.7 range, which is too lean for forced induction. Very very annoying.

Anyone got any idea as to what makes this ECU use its 3D map rather than closed loop lambda?

Car is a 2006 Panda 4x4 with fly-by-wire TB and Marelli IAW 59F ECU
Fingers crossed!

Thanks,
Phil
 

woj

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That is actually the problem with even our older ECUs (16F, 18F, ...), the range of closed loop operation is very wide. Once the engine heats up it goes into closed loop. For my ECU (in its stock form :D) open loop only happens during strong deceleration (what you noted), or at very high engine load (high I mean high, 90%-ish and above). Otherwise it is closed loop, even when you suddenly accelerate.

For our ECUs the only way of switching to open loop (without reprogramming the chip) is to disconnect the O2 sensor. Yours probably has two, and I can bet small amounts of money that disconnecting both of them will cause a major panic attack in the 59F ECU.

Two questions: how do you know that it is in closed loop (what is your diagnosis method)? 13.5 AFR seems a bit low for closed loop operation (closed loop usually means 14.7 abouts).

Where is the thread with your supercharger project please :worship:
 
OP
OP
R1NGA
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Thanks for the info folks. I must admit that I am not technical enough to fly the mapping process myself, I leave that to my expert mate Paul. He can record and monitor whatever he wants and in fact I may have got the closed loop AFR wrong - it probably is nearer 14.7 of course. I will speak to him about the O2 clamp.

My car has 2 lambda sensors and I have been told that I could probably remove the 2nd (downstream) one, wrap it in silver foil and then tuck it out of the way, still connected. The remaining sensor could then have it's signal intercepted and played with by the Dastek to deal with the fuel trim. Could even wire a microswitch to disconnect the signal at full throttle (under pedal) so that the car has no choice but to go open loop? Guess I might get a Mgmt light disco up on the dash though.

Phil
 
OP
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R1NGA
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Once I have the car sorted, I will post a proper thread about what we ended up doing. Right now, however, the STD ECu is causing a real headache. We're now looking at knocking out the O2 sensors and forcing open loop so that we can map things correctly. We can deal with the CEL, but concern is for MoTs in future, although car still has CAT in place.

If this fails, then I think I will admit defeat and do what most people said in the first place, ie: go standalone, but also keep the OEM box in place for the rest of the dash and electrics.

Anyone who can give info regarding this type of hybrid hook-up, then please post!

Phil
 
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