Power loss after truck warms up.

[alpinhi]

Hey guys,
I have a 96 CCSB, auto, 185k, and the only mod I have right now is a Tymar. I have noticed that I have great power and throttle response in the morning when the truck is still cold. On my drive into work it will lose that power and throttle response as the truck warms up. The truck is running fine, no check engine light or other issues, just seems to lose that get up and go. This isn't new, it has been going on a couple years I think. I am just wondering, would be nice to have that power all the time. The reason I ask is I was going to do a flush and fill to the cooling system system today and I heard that the T-stat may cause issues like this. I thought I might go on ahead and change it out if this is the case.

[Woodturner Nate]

Sounds like you need a good oil change, including draining the HPOP oil. According to a few sources, the exchange between the low pressure oil system reservoir (the crankcase oil pan) and the high pressure oil pump reservoir, the flow between the two is far lower than you might think, ending up with old oil in the HPOP system, which powers the injectors. When it's cold, it has enough viscosity for good power, and when it heats up, the power goes down.

When I did my last oil change, I first changed the crankcase oil. Then I used a vacuum pump to drain the HPOP reservoir, filled it back up (about 1 quart in the reservoir, which you can't really over-fill--it drains back into the crankcase if you overfill it), then I let the engine run for a couple minutes, letting all the new oil in the reservoir enter the high pressure oil lines and into the injectors. Then I drained the HPOP reservoir again, and filled it again with new oil. The video I watched on powerstroke help dot com seemed to suggest doing this a third time, but two times was enough to get very clean oil in the reservoir after letting the engine run and the high pressure oil to circulate. I was AMAZED at how much dirtier this oil was than the crankcase oil. I think the power and response was a bit better after changing the HPOP oil.

[kraker829]

I would suspect the idm if the above oil change doesn't improve it.

Sent from my SPH-D710 using AutoGuide.Com Free App

[jesilvas]

I will say the HPOP oil change is fine, every now and then. But not needed every time.
I'd suspect a possible HPO leak also. I'd scan it.

[alpinhi]

Last summer I was having issues with the truck. I ended up replacing the HPOP regulator, changed the oil in HPOP, replaced some fuel lines, fixed a bad ground on relay that runs the IDM, and cleaned the FPR screen because it was clogged. The fuel pump was replaced about 2 yrs ago. Sorry I didn't mention all this before. I'm still learning and I didn't think that some of this may be pertinent info. I regularly change the oil about every 7k with Rotella. How do you go about scanning the HPOP?
Thanks

[jesilvas]

You have to have a tool to monitor live data.

[alpinhi]

Originally Posted by jesilvas

You have to have a tool to monitor live data.

Thanks, Ill see what shops around here can do that.