2003 F250 7.3l, stock except for 4" exhaust, intake and RiffRaff's billet compressor wheel.

Truck runs fines, but I noticed yesterday that it builds up boost faster when the motor is cooler. Just seems more snappy, you could say

After driving for a half hour or more it just spools up slower than when it's cool but still warm. Last night I had to run down and get some pizza after the truck had sat for a little over an hour and it spooled faster, up to 18psi. Motor was still warm from driving over 170 miles. While driving that 170 miles it was doing something what I would call lag, would only boost up to 11-12 when passing someone.

ideas?

 

The first things that come to mind for me are boost or exhaust leaks. But those should show their ugly head all the time.


Then, I'd ask how old is the oil?

What type of oil are you running?

How many miles on the truck?

How does your truck start when it's all warmed up?

 

How long ago did you do the compressor wheel? Was there any play in the turbo shaft? High temps could cause more drag in the turbo bearings if there is a problem there. But you could also have a high pressure oil problem starving the engine of fuel.

 

Oil has 1000 miles on it

Running Rotella T 15-40

Truck has 150k

When warm, starts fast.

July is when I did the wheel. No play on the shaft. Rebuilt the turbo in July when I did the wheel

 

It could be all of the above but I would start by checking for up pipes leaking and boost leak tester.

 

Is there a DIY boost leak tester available that won't cost me a fortune?

 

Do a search there's a thousand of them

 

Here's one cookie88 made up.

 

I would have to agree as it sounds like something is heating up and expanding causing a boost leak. Get your boost leak checker and check the boots at the intakes under the spider and inter-coolers. Also consider something could be causing the waste-gate to open more after it warms up?



In case its something more complex you need to monitor your sensors. You didn't mention you have anything so I will recommend the cheapest alternative.

https://www.ford-trucks.com/forums/1...-in-bacon.html

This will enable you to gather data when cold compared to operating temp if something funky is going on with your HPOP/injectors etc.....

 

Check fuel pressure while driving.

 

Sorry, my good friend... this needs revising. I had an intermittent boost leak... not easy to find. My intake plenum seal was weak, so it would be good at times, then give way.

There's a commercial product available?

 

OK, so some boost leaks are intermittent. I guess some exhaust leaks could be the same. Checking for leaks should be the first thing to do for sure. I was also thinking that possibly the ICP was dropping when warm from the o-rings failing. That is a common problem when they get some miles on them.

 

For stock turbos.
http://www.dieselsite.com/dieselsite...ector-4-1.aspx
For ported housings.
http://www.dieselsite.com/dieselsite...etector-4.aspx