I have a 89 s13 with a Redtop sr20det swap i did myself,as i was finishing the swap summer last year i had a couple small issues (not anymore but led to this issue) first the knock sensor threw a code, then the CAS threw a code (intermittent) so the engine would run GREAT about 20% of the time AFTER i put a new knock sensor, the CAS would randomly send a code and of course the timing would be pulled out BUT the AFR was always perfect even when the ecu was puling timing the AFR would sit with 2 lights lit right between rich and normal (i know its not a wideband BUT it does show high and low at the same time which in 3 different cars ive had the same model gauge and o2 separate from the cars o2 of course and it always showd 2 lights next to eachother telling me about 12.5/13:1 ratio when the car was running proper) so no matter what under any throttle the ratio would be correct.

THEN i let the car sit for about 6 weeks while i redid the intake (removed the flex tubing and moved the MAF further from the turbo) also i rebuilt the power stearing rack and redid the power steering lines (bad leake started in the rack and small leak in the lines) also i purchased a new CAS but had not installed it at the time of putting the car back together. The second i got the car started after all this sitting and working on it fuel started leaking from the vent line / valve under the car by the diff, it went away after i started it the 2nd or 3rd time, so i test drove it since the leak stopped and from that day till now i have tried MANY things to remedy the current issue of leaning out.

Current issue - The day i started it and it leaked fuel then stopped leaking NOW the AFR is either so lean it doesnt register OR as it accelerates it then shows all the way from MAX lean to proper rich/normal AT THE SAME TIME, so now 10-12 lights are lit up on the autometer AFR gauge at the same time (making me assume 1 or more cylinder is getting LESS fuel than the others) the car now wont accelerate under any boost and you have to let off the gas to almost nothing to get the car up to speed (rpm doesnt matter it will climb more and more with less and less throttle, but as soon as boost kicks in then it stops climbing and back fires)

So far ive tried - I installed the new CAS and timed it (using a jumper lead between the coil and the spark plug) set it to stock setting (this helped a bit im assuming the engine came with the old one not timed perfect), i then changed the plugs (helped a bit), i then checked the fuel pressure (46 at idle 51 atmospheric, 61 @10psi boost) i rigged the gauge up through the top of the hood so i could drive with it and pressure seemed perfect under all loads and even while backfiring pressure never dropped, i installed a z32 larger fuel filter under the hood, i replaced all SOFT fuel lines front and back under the car under the hood,at one point the stock o2 popped the fuse so the ecu wasnt seeing the AFR so i put a new o2 in (stock replacement which shows in consult and goes into closed loop after warming up), i pulled the injector rail up about 1.5"above the intake runners and idled the car while watching the spray and at idle each injector had a perfect clean spray pattern (no drips or leakes etc...), Lastly i checked the voltage at my in tank 255lph walborh pump and i was getting about 2 volts LESS than the cars electrical system at the pump to i ran a relay and fuse right off the battery (both ground and power through relay are only 4feet long straight from the battery in the hatch area) this also helped a little (now getting 13.2 to 13.8 volts at the pump vs 10.3 to 10.9 that i was gettting).

Each thing i tried helped a little or only helped for a drive or two, i dont know what else to try, at idle i get 18" vacuum yet it idles very rough and at 650rpm after it warms up (even though through consult and IAC i set it to 850 ) it always goes back to about 650rpm and shakes the car at idle. also to note the car runs 170 to 180 on the freeway and sitting in traffic it gets to 190 then the fan kicks on to 185, as soon as i move its down to 180 or less always (stock thermostat with huge aluminum radiator)

Any help is appreciated

UPDATE - Today i changed the plugs again (iridium ngk 11 heat range), i havn't changed the plugs since i started troubleshooting this issue about 3k miles ago (before the fuel pump relay, before timing the car with the new CAS) and right after changing them IT RAN ALMOST PERFECT, i made a couple part throttle then 2 full throttle runs through a gear or two and NOW the AFR is showing 5 lights instead of 12, its showing a low reading of about 14.5 and at the SAME TIME a high reading of 13.5 (roughly its not wideband) this is much better than before changing the plugs where it was reading WAY PAST lean (over 16:1) to the same about 13/13.5:1 lighting up almost the whole gauge at the same time, BUT before i couldn't even press the throttle down more than 1/4 or 1/8 sometimes, on this test run i could give it any amount of throttle and at first it broke up slightly then kept revving under part throttle but got BETTER each time boost kicked in (o2 learning variable i assume) and on the 2 full throttle runs through a gear each it DIDNT break up AT ALL.

Im going to hook to consult and record the results, also im searching for a vac/boost leak. i dont know what else to try,

Any suggestions or even just "hey try this" would be appreciated, i really want to get this motor right so i can get Nistune and really start upgrading this thing. ALSO its my daily driver so its important to me...