Engine/Transmission (1994 - 1998) Another smoke question

[Johnstra]

When I really get on it, my truck pours out the gray smoke. Full throttle, 2200+ RPM and about 24 PSI boost when I see it most.



The smoke isn't black so I don't think it's over fueling.



All my driving is between 5k and 9k feet.



What's the deal?



-john

 

[Johnstra]

Anybody?



One other thing... my truck uses very little oil.

 

[RJPotts]

Is everything in your sig everything done to the truck?

Have you ever had it dynoed?

Sounds like normal overfueling to me. But the stuff in your sig would suggest otherwise. If it runs good, and all seems well, I say don't worry about it.

-R. J.

 

[Johnstra]

Yep, my sig is up-to-date. My injection pump is tuned to 20% over stock, so I'm not surprised that it's overfueling. I just always though overfuel == black smoke and mines more what I'd call gray.

Thanks for the input!

-john

 

[Vaughn MacKenzie]

Mine's grayish too. I've noticed it on other 12-valves too, so it must be a "12 valve thing"



Mine smokes inconsistently. If I hammer it at say 2000 and already have a bit of boost it pulls hard and doesn't smoke much at all. Boost is 35-37 psi. Hammer it at a little lower RPM and it smokes like a coal train and doesn't clear up one bit, even thought there's plenty of boost. I thought it was my pump but it did it after having it recalibrated, and it does it with the calibrated 175 pump I replaced it with.

 

[bmoeller]

If the truck is up to temp, the gray smoke isn't a problem. It means you have plenty of air. Need more fuel to make it black again.

 

[Johnstra]

Well, I guess I'm going to have to drop my #10 plate in and see what it does



Vaughn - Mine's actually kind of inconsistent too. There's a sweet spot in the RPM/Boost band when it doesn't smoke.



-john

 

[BTighe]

mines consistant. happens every time i skip a gear shifting. sound like the gray smoke is an underfueled problem. better take care of that. it is a 12valve thing.

 

[T-Bone]

Bmoeller,



Uh oh. All this time I’ve been struggling with not turning things up!?! I’m at 7k feet with DDIIs and a #10 trying to turn 295s with 3. 54s. My plate is almost all the way back and I still get a good show of gray smoke. At night, it’s pretty constant. Are you saying I should center up the plate?



Thanks,

T-Bone

 

[McLaughlin]

What is your fuel economy like? You may want to have someone follow you through a couple of stop signs/lights and watch your exhaust. A couple of months ago my fuel mileage dropped to about 12 mpg. Since then I've noticed and been told that my truck constantly is producing gray smoke. It is especially noticable when stopped at stop signs and lights. I haven't found the source of the problem -- yet.

 

[Johnstra]

My fuel economy is good... about 18 MPG now w/ winter-blend fuel. 20-21 MPG on straight #2 (or on B20). I don't have much if any noticeable smoke driving normal - that includes starts/stops hill climbing etc. Only when I get on it hard.

-john

 

[McLaughlin]

My fuel economy is good... about 18 MPG now w/ winter-blend fuel. 20-21 MPG on straight #2 (or on B20). I don't have much if any noticeable smoke driving normal - that includes starts/stops hill climbing etc. Only when I get on it hard.

-john

My take is that your truck is working about right then. Sounds like you have just a bit of excess fuel use at heavy acceleration but not enough so that your smoke is black.