Loss of speed/power need help long read
 

hi all. So here is the story with my 2001 7.3. For he last few months I have been having a few issues With it. First, the idle drops when I brake it drops so much the truck almost stalls but catches it self and idles fine it keeps doing this while braked. Furthermore, it only does it once the truck has been driven for a while say 40 minutes. It also does it when it is put into reverse. I think it might be an issue with the transmission or tq dropping Rpms from not being able to downshift into the right gear when braking. But, Iam not sure any input would be great ?????

Okay now for issues number 2. Recently I have been driving my truck and noticed a lot of power loss. Like I will drop from 40 to 25 mph going up a incline the truck doesn't smoke or any thing going up the incline but just seems to struggle hard. Once on flat road it runs pretty smooth but still has the issue of limited power. I'm starching my head at this one.
Okay now a list Of things I have checked to see if it's the issue
-replaced icp and pigtails
-whole new engine wiring harness to to previous owner splicing and running wires all over
- new ebps Sensor and tube
-new fuel filter and air filter
- new glow plugs and Uvch and glow plug solenoid
-new thermostat
-recent oil change
-changed the ipr valve but once I put s new one in it the truck ran horrible now I have the stock one back in and the truck runs the same.

So long story to the end. Iam not sure where to begin to try to fix this. I don't have a scan tool. I checked the up pipes behind the turbo and they look to be pretty dirty so maybe a turbo leak? I plan on testing the fuel pressure and see how that does would that tell me if the fuel bowel or the frame pump is bad ?Could it still be the icp or ipr and I just got a bad one?

Sorry this is a long read but Iam stumped lol thanks to whoever reads all this and might give me some help
Cheers al

Fuel pressure will cause this. If you have the orginal fuel pump its flow and pressure may be dimished. The fuel tank intake screens are easily clogged. I know this is a total pain to check, but it might be the issue. I replaced my factory fuel pump with a FASS and have not regreted it. On a different note, do you have a source for a new wiring harness? I need one bad. Thanks,

If you or anyone can get me a new engine wiring harness I will provide a finder fee for the info.

Check the exhaust back pressure valve. It's in the pedestal for turbo.
 

Mine does this. I unplugged map sensor to run till new turbo and pedestal comes in. Anyone wanna say which turbo I need for bone stock best turbo. Throw me an idea.
The ebpv closes when cold to heat up engine. If it doesn't open you build excessive pressure. If it stays open then you can't build enough air flow and you cavitates. You = me. Or get a delete pedestal and loose the flow restriction. But takes about 20-25 minutes to warm up here in Tennessee