Engine/Transmission (1998.5 - 2002) No Power

[RDavies]

O. K guys this is what's happeining. Leave in the morning when truck is cold every is great. After about 10 miles down the road it feels like someone slipped a duramax under the hood I can have the throttle buried on the floor and it will pick up speed at it's own sweet time. Stats: fuel pressure pre filter 9 P. S. I idle, 7. 5 @ 50 m. p. h and 4 P. S. I W. F. O Post filter pressures are the same. This is when the truck is cold. When hot I can't pull the pressure down below 7. 5 Could the M. A. P sensor be to blame?

Second question how do you list your signature?

 

[Ted Constantine]

Sig=



Go to the User CP button under the banner at the top of the page.



Go to edit profile and you can enter you sig there.



You then need to be sure that the box is checked under you message when posting "show signature"

 

[Bigsaint]

If you are not getting a check engine light and codes, I'd check the boost lines and make sure all are tight. Doesn't add up that you have power when cold and not when hot, with the turbo connections, but I'd check them just the same. Just my $ 0. 02.



Scott W.

 

[MCummings]

Get a boost pressure reading and that should tell you alot.



Sounds like you aren't making Boost, or the Computer isn't seeing much boost (if any).



Do like BigSaint said, then if the problem isn't solved, check your boost pressure. (Or vice-versa?)



Merrick Cummings Jr

 

[joel]

Lift Pump

Those numbers look pretty low for your fuel pressure. I think the spec is around 13. 5 at idle and no lower than 8, I think, at WOT. I'd start there.

 

[RDavies]

I checked the boost lines and they are all tight. The boost that I am making when cold when tromped on is 15 psi. When hot (low power) the boost just sits at 5 psi. If I just roll on the throttle the speed pickup is VERY slow. The only way to get any more speed is to kick it down into passing gear then the boost will climb to 10 psi. , but not for long. I am thinking of changing the IAT and MAP sensors because I feel that the engine is seeing little if any boost and therefore not supplying any diesel. Am I right?

 

[Greg Boardman-RIP]

what did you find out?

 

[Steve Campbell]

It seems to me...

that Marco talked about the Water Temperature Sensor as a culprit in a case like this.

 

[zimman20]

You mean the IAT? That Marco was talking about?

 

[Rob Levandoski]

I've had the same problem on several occassions and the dealer has always indicated it was the MAP sensor. They've worked on the waste-gate as well and once in a while I still get the same problem. Feels like an anchor was thrown out. Searching for a fix myself.