I noticed my car spits out quite a bit of black smoke so I decided to look at a datamaster file. While cruising at 60, my Lterm counts are right around 108 and Sterm counts range from 86 to 118. The counts while accelerating are normal - 128 counts - so Im wondering are the counts usually that low when cruising at a constant speed? Thanks

 

Something is causing your engine to run excessively rich. That's why the long terms are down to 108, and still not enough to lean the engine out, forcing the short terms to pull even more fuel. When you go WOT, IF your PCM was pulling fuel out (long terms below 128), it ignores the long term corrections and defaults to 128. That's why you get the black cloud. At low loads/cruising, the PCM is pulling out a ton of fuel to keep it from running rich, and at WOT it doesn't pull that fuel out, so it runs pig rich at WOT.

You need to find out what's causing it to run so rich. You want your long terms as close to 128 as possible, at all times. Anything more than 5% above or below 128 indicates you have a problem than needs to be corrected.

 

Thanks for the info. I was searching other threads and checked my MAF - in backwards. Hopefully that'll fix it. If not, can I have my tune from PCM4less fix it?