ecu code 55 ?????

[bigRy]

xs081

89 s13 w/sr20 redtop, intake. bov, frnt mount, test pipe, 3in exhaust

ecu showing code 55. ive two places one saying no malfunction and other saying some type of other malfunction. car idles rough, getting black smoke from tail pipe. car semms to run fine when cold but when warm up starts to bog. o2 and maf sensors are fine. new plugs. cant seem to find any i/c piping leak. dont know what to do . any help would be greatly appreciated. thanks

[NISTECH]

55 on an american made nissan engine is ok. sounds like it runs rich warm check coolant temp connection and resistance

[bigRy]

its jap sr20 redtop. i've heard code 55 is either no malfunction or other malfunction.