Hi Guys,
My first post on the forums here, been reading as much as i can after recently buying an MPVI pro I still have lots of questions though, so figured i'd start a thread to start improving my understanding and get a better end result!
So the car was originally tuned by a well known workshop in Melbourne (whilst i owned it). I've always had interest in tuning myself, so figured why not delve into it myself so that i can dial it in better over time. It had also developed a bad miss at idle after changing the fuel pump and putting some valve springs in, so figured it was perfect timing to start trying to get it right on my own. The more i look at what the major workshops do, the more i'm glad I've started tuning my own car I guess no one cares for or will spend the time on my car like me
So the first question is around the slope data that i'm currently using. The car has genuine ID1000's and i've recently gauged the base fuel pressure at 67psi at idle with a KPM twin pump in tank system and reg to suit (that comes in the kit). Now i realise that the base pressure is higher than the stock 4 bar, so figured that the injector slope info that was in the car before would be wrong, as it had a stock pump setup.
I also learned pretty quickly, that since changing the pump setup it was adding up to 15% on the long term trims and up to 15-20% on the short terms. Waaaaaaay off...
Now I've measured the base pressure, i've plugged that info into the ID data sheet and come up with the numbers required. On the first re-flash, it was waaaay to lean using the data from the sheet. The low slope was up around the 130 lb/hr which was obviously compensating for the higher than standard fuel pressure.
I've managed to bring the slope numbers down now for the low to 121.500 which has seen in the logging the LTFT's come down to basically 0, the most i've seen is +1.8%. So much better on the commanded lambda front. The High slopes I've also richened up, by bringing down to 105 ish lb/hr to bring it closer to the commanded under heavier loads.
So back to my original question - regarding the voltage offsets. I'm still using the voltage offsets calculated by the ID spreadsheets based on the higher slope numbers. Should I now be reverse calculating to the offsets based on the lower slope numbers as now that's what it's running to keep the commanded lambda in check?
This is what i'm currently running for the voltage offsets:
Capture.JPG
What do they look like to you guys? I had to fudge or guess the highest voltage numbers as the ID data doesn't go up that high. I don't think the charging system would get that high either. I could always interpolate that value I guess...
There will be much more questions to follow
Cheers,
Rob