Black Smoke, Less Fuel Mileage

[gulfyankee]

1994 6.5 TD, extended cab dually. 127,000 miles. 3" straight pipe, aftermarket air filter. Started have boost surging issues at cruise...ie....at 70mph steady speed flat surface the boost would fluctuate from 2-6 lbs every 5 seconds or so. bypassed the vacuum system and made a turbo master, set at 12 lbs max. This other problem started a little while before that happened. Getting a good bit of black smoke at takeoff. MPG has dropped about 3 MPG average. Seems to take longer for the turbo to spool up (higher rpms) I used to be able to power brake it and build max boost and no smoke, now no boost and alot of smoke.....
So am I looking at replacing the turbo, IP, injectors, PMD, or what? I feel like it is dumping too much fuel.....

 

[Matt Bachand]

Take off that aftermarket air filter and make sure no obstructions or parts are lodged in the turbo's intake.

Sure sounds like its starving for air. That or perhaps your spring on your homemade TM isn't strong enough, causing it to fluctuate???

 

[gulfyankee]

no its not fluctuating any more since i put the TM on it.....I'll check for the obstructions

 

[Acesneights1]

Turbo could be on it's way. WOuld like to see some pics of your" aftermarket air filter setup"
Black smoke on these is usually lack of boost.What are you reading the boost with ?

 

[Matt Bachand]

Turbo could be on it's way. WOuld like to see some pics of your" aftermarket air filter setup"
Black smoke on these is usually lack of boost.What are you reading the boost with ?

Exactly. Black smoke is unburnt, or partially burnt fuel. Meaning too much fuel for not enough air.

Usually Caused by 1 of 2 things.

TUrbo not putting out boost.

Air intake clogged/not allowing enough air.



A clog down stream on the exhaust could have similar effect too, unlikely if straight piped.

Are your EGT's sky high ??