unknown problems

[jlog]

On real heavy acceleration I noticed a big puff of black smoke out the exhaust. Other than that the truck started fine and ran good and sounded OK. When I took it in for service I asked the tech to check it out he took it for a test drive and got the same cloud of black smoke. He then put the scanner on and got the following codes 74; 29; 31; 46; 49; 57; 62; 78. he checked the waste-gate solenoid - OK, barro sensor - OK, and vacuum supply was in spec, he cleared the codes and took it for another drive - no black smoke and the codes didn't return. I have been driving it steady since then and it runs great. The truck is a 1994 6.5 auto with 175,000 km, stock, no guages

John

[More Power]

For a series of unrelated codes, I first suspect an electrical problem of some sort - i.e. alternator, batteries & cables, ground connections, ignition switch, corrosion in an electrical connector or junction block, and so on (not necessarily in that order).

Jim

[jlog]

So far no repeat of problems no black smoke on acceleration and truck is running great. Any hints on how to find a short or electrical gremlin
John