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Greetings all,
Looking for advice on tuning my car after several modifications were made. I'll post the whole sordid saga when this is all over... well, maybe mot sordid, but definitely silly.
I've recently installed a tweaked APC, 30# injectors and a rising rate fuel pressure regulator in my 1988 900 SPG. Originally, I just had the tweaked APC in there because there were some running problems with the larger injectors... as I was waiting for the RRFPR.
With just the tweaked APC and the stock injectors, everything was quite smooth. I could boost fully , just into the red (actually it went quite a bit further than that, but I was worried about running lean, so was conservative)... it pulled nicely and had no problems.
I then installed the 30# injecors and the RRFPR. I also adjusted the AMM to 225ohms to correct the idle. This was without actually measuring anything. The problem I have now is that it seems slower than without the large injectors, and more worryingly, sometimes when accelerating hard (in 2nd or 3rd) the engine will start to buck... usually when the pressure just gets into the red (but I have had this happen when the pressure is below the yellow/red interface). It seems to exhibit this behaviour when I stomp the accelerator hard. If I gradually accelerate, I can boost to my heart's content without a hitch... except that there doesn't seem to be as much power there as before I had the injectors and the RRFPR in.
So.
My question is really... how would I go about tuning the A/F mixture and other things (?) so that the car is running as optimally as it can given that it isn't stock? My main concern is that I don't really know anything about how the car is actually running. I don't have a wideband o2 sensor, and was hoping I wouldn't have to install one.
I've tried the tuning suggestions for the AMM at idle, but cannot get it to run normally (testing voltage fluctuations at the test harness)... and understand that it might well be impossible to do this. What I am looking for is a procedure I can do (or measurements + adjustments) that will at least get the car operating as close to optimal as possible... and of course fix my problem above...
Thanks for all your help!
Vincent T_i_ng.
posted by 64.180.126...
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