Black smoke

[buldog7]

Jim,

My son has a 1996 6.5TD GMC Yukon that is producing heavy black smoke, won't get above 2500 rpm's. 178,000 miles starts good. Suggested source or fix. I have a 1995 C3500 dually, 6.5TD, SES light on, DTC codes 18, 35, 36, 54. New Grey PMD installed recently. Intermitenly goes into limp mode when I get at or just above 2500 rpm's. ? Thanks for your time!

[DmaxMaverick]

Black smoke is too little air/O2 for the fuel that's trying to burn. Start by looking at the simple things. An air filter or intake obstruction/collapse will cause this. Also, check the DTC, which should be present if it was in "limp mode" at any time, and it may also limit engine RPM. If the DTC is wastegate related, it may explain the black smoke and the limp mode.

[buldog7]

thanks Dmax