Engine/Transmission (1994 - 1998) Power loss

[LHartman]

My dad's truck is experiencing a loss of power and I'm not sure where to start. It's a 96 auto 4x4. He was towing his 5th wheel and said that he went to accelerate up a grade and noticed lots of smoke, high egt's & less power. He said that he could mash it to the floor, hit 40lbs boost and bury the pyro. He has a plate (#10 probably), injectors and a different exhaust housing.



I inspected the boots and intake for leaks, but found nothing. I took it for a drive myself to get an idea of what it was doing. Upon heavy acceleration, there is lots of smoke, good boost, mild egts (700-800 post turbo), but not the power is usually has. The smoke would clean up quickly, but was lacking power.



Fuel filter? Overflow valve? Any suggestions are greatly appreciated guys.



Loren

 

[FourBarR]

black smoke usually lots of fuel , but lack of air. air filter, leaks in boots, bad turbo. take the hose off between air filter and turbo, see how much movement in the shaft. check the air filter, if you dont have a new ,try it without see if it makes a difference. go to the search function here , there is a method to make a test tube to check for leaks on the boots.

 

[LHartman]

black smoke usually lots of fuel , but lack of air. air filter, leaks in boots, bad turbo. take the hose off between air filter and turbo, see how much movement in the shaft. check the air filter, if you dont have a new ,try it without see if it makes a difference. go to the search function here , there is a method to make a test tube to check for leaks on the boots.

I was looking for the thread to make the test tube but didn't have time to search the threads. I checked the air filter and turbo shaft. Both are fine. I'm leaning towards an intercooler leak.



Thanks FourBar

 

[Loren]

Loren,



I would imagine that it's unlikely, but it sounds like it's possible that the fuel injection timing has gotten retarded. Late ignition would cause unburned fuel (smoke) and low power.



This might be an expensive thing to check, but if the intake system checks out, it's the next thing that I'd look at.



Good luck,

The other Loren

 

[LHartman]

The intercooler checked out today, so I figure it probably timing. Thanks for the reply guys.



Loren

 

[LHartman]

Well timing, turbo, intercooler and all hoses check out fine. For some reason the mechanic feels the problem is in the transmission. I'm not sure where he's coming from. I drove the truck and noticed no problems with it shifting etc. Not sure how they are coming up with a transmission problem when sometimes the boost is high and then low at other times. They said it's not kicking down (the transmission) like it should. It was explained that the truck shifts like it always has. I don't know if the wastegate was checked, but this could cause a high/low boost situation, correct? I'm trying to brainstorm here... ...

 

[Mike760]

I have been experiencing the same problem. I have a 30' GN stock trailer 7500lbs unloaded that I pull. I used to be able to pull a moderate grade without a problem at 65+ mph. Now I am flooring it and getting knocked back to about 40mph on the exact same highways. And this is unloaded! This started a few months ago. Without a trailer, it drives normal. I have 150K and a new trans with about 20K on it.

 

[Joe G.]

Mike,



Check your AFC. If it's not smoking a lot and you have low power the AFC may be the problem. There is a plastic tube from the manifold to the AFC that can crack. If you have an EGR (CA truck) soot may have plugged up the AFC.