The problem is most definitely not the fact it is an AEB ECU on a 6cyl engine, not quite sure why anyone would think it was, we have supplied many hundreds of such for 6cyl (including Bongo's) without problems, suspect an underlying problem with the car or possible installation error but have not got to the bottom of it yet but expect we will in the end.
AEB are the biggest and most successful maker of LPG ECU's so rest assured, they work just fine on 6cyl engines.
Dai (Classicswede) and I have in the past spent hours on the phone to each other (calls both ways) trying to solve unusual reading type probs on certain vehicles converted with certain ECU's where all the problems went away after fitting a different type of ECU - most of those situations involved rpm reading and extra injection related problems rather than pinj reading problems (pinj seems to be the problem here).. Those other situations will remain mysterious regardless of the outcome here, you'll recognise both of our knowledge, experience and diagnostic abilities with AEB and a very wide range of other systems. I will have converted plenty 6 cylinder Mazdas (and other marques) using older AEB ECU's without problem but (Mazda's aside for the moment) have had unusual issues with newer AEB ECUs particularly on 6 cylinder engines. That said (and putting things in perspective) modern AEB ECU's are still my usual choice for 8 cylinder engines, I'm not anti AEB or trying to do anyone a dis-service by mentioning my experiences/findings. Above I mentioned how changing greyed out rpm settings can solve unusual problems with extra injection lights flickering, rpm dropping out and ball bouncing - probably not something most have thought to try, shouldn't work but does, but why does it work? Though I'd bet you won't agree changing greyed out settings can have an effect and I don't think we reached a concensus the last time we discussed systems on forum http://www.lpgforum.co.uk/viewtopic.php?f=28&t=13843&p=108508
On the main topic I reckon Dai's suggestion of setting MJ sequential a good idea. The issue does seem to be that the ECU isn't interpreting Pinj properly (for whatever reason) - probably not due the type of ECU on the type of engine in this case (I said I wasn't sticking my neck out in this case, because it is different to issues I've seen before), could be the Mazda injection methodology point again, in which case Dai's suggestion has the potential to sort all the issues and do a good job of it too (I reckon AEB ECU's were/are particularly good at sensing injection methodology changes on Mazda's etc, i.e. the leaning on Mazda control works better than on other ECUs). Other than that, what might we suggest is wrong with the car if it pulls properly on petrol under all conditions? It wouldn't pull properly if manifold pressure reaches atmospheric but fuel dosage is only half what would provide correct mixture. If Col has followed all advice so far and Dai's MJ injection setting suggestion also doesn't work (even after trying the MJ setting in conjunction with various extra injection filtering settings) it will be a case of what to suggest next though... In which case if the car were here I'd try an old spec ECU, an easy thing to do which might help rule out or confirm ECU related issues, reckon I can think of a couple of other people who would likely try the same.
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