bruce80

causes of spark retard only at wot goes up as high as 11.8 at wot. up to 3/4 pedal no knock retard car is 1995 trans am thanks.

bruce80

seems to be running rich to. black soot on bumper

OBE1 95Z28

Black soot on your bumper could be from oil "blow-by" and not a rich fuel mixture.

bruce80

blow bye ? i clean the bumper and its black again after a few days been like that for 2 years.

Injuneer

Get a data logging software, and run some data logs under various operating conditions = appears you may already have it, since you know the knock retard. Upload the data file to an FTP site, so people can take a look at it, and tell you if it shows evidence of running lean or rich (you mention both???).

bruce80

not sure how to upload at wot rpm 5150, map kpa 96.0 fuel trim 18 lterm 128 sterm counts 133 / 145 o2 mv 613 / 93 spark advance 25.0 spark retard 11.8 knock count 2383 if you need any more info let me know thanks.

Injuneer

A single frame of data is virtually useless. You need a complete file.