i have a 93 e-150 with a straight 6 , 144,000 miles, when i leave the van running with the a/c on, either at a long light or drive thru at the bank, black smokes starts coming out the tail pipe. the van starts to look like a diesel van. i smoke the hell out of people next to me. does anyone knows what causes this?

 

Black smoke usually means over rich combustion. Why, could be as simple as a leaking fuel regulator, check for gas in the vacuum line & diluted oil in the crankcase. It could be trouble with a sensor & be revealed by fault codes. Over rich conditions will ultimately carbon up the plugs & lead to misfiring, also overheat the cat, even destroy the cat.

 

i hope it don't destroy the cat i just put a new complete exauhst system in from the headers all the way back with new o2 sensor,cat and muffler, it only does it when i'm idilling with a/c on , then i will start driving and it will eventually clear up. i am still trying to get the front end straightend out, new radius arm bushings,upper and lower ball joints, shocks, i took it to get aligned ,they told me they get the camber correct , it needs an alignmet kit, they can do it for 400.00 dollers, the print out says it needs 3 degrees, i just bought the kit for 20.00 at napa i gonna put them in this weeekend, i did the ball joints last week that the hard job camber cams are easy