Cutting out above 2500 rpm

[blackbetty]

Hello everyone, I have been reading this forum for a couple of months and decided to join today..
I have a 96 f350 cc 4x4 that I bought a couple of months ago. She runs fine except for that power drops out over 2500 rpms. When truck is in park, you can rev the engine and when rpms reach 2500 it smokes and skips. (sounds like a fouled plug on a two stroke) I have changed fuel filter, shimmed fpr (thanks to this site) , installed edge evolution on tow program and installed 3" downtube. These mods were done within a week of each other. The only change was the program. In park will rev and hit rev limiter but driving the truck, it will not rev past 2500 smooth. It is like someone turning it on and off. If I have my rear window down I can hear the rough exhaust note. Can anyone suggest something I am missing?
Thank you

 

[95_stroker]

How many miles on the engine and how many since last oil change?

 

[blackbetty]

Miles are 340000 and just changed oil 300 miles ago.

 

[95_stroker]

340,000 miles........any injector work done upto this point?

 

[blackbetty]

Not to my knowledge. I bought the truck 4 months ago. I had a diesel shop check the truck and came back with no codes. The passenger uvc has been replaced as the connectors are new.
I have thought about injector or injectors but did not know of anyway to test them. Is there a way? The truck does seem to defuel at that rpm range. It will surge if you stay in the trottle. Thanks for the fast reply.

 

[95_stroker]

Not to my knowledge. I bought the truck 4 months ago. I had a diesel shop check the truck and came back with no codes. The passenger uvc has been replaced as the connectors are new.
I have thought about injector or injectors but did not know of anyway to test them. Is there a way? The truck does seem to defuel at that rpm range. It will surge if you stay in the trottle. Thanks for the fast reply.

You can do the injector buzz test and the cylinder contribution test.

Read about them HERE.

 

[action4478]

How soon after you changed the program did the problem begin? Also , does this have a cat & muffler still?

 

[Radarman]

In park will rev and hit rev limiter but driving the truck, it will not rev past 2500 smooth.

That REALLY sounds like lack of fuel. If you can, put a fuel pressure gauge on it and take it for a drive.. plug it into the shrader (sp?) valve fitting

If you got the fuel filter and the screen on the shrader valve, then that leaves only a few things. Fuel pump, in-tank fuel screen, or something in the lines.

 

[blackbetty]

Thanks guys. Action4478 the programmer helped the problem. Without the programmer it would not hit the rev limiter in park and driving really would not rev past 2500 to 2800.
radarman I agree with defuelling but would it be due to fpr or ???
Testing the fuel pressure - what type of quage? psi reading am I looking for?
Shreader valve is 1/4" ?? correct or is there a link to testing?
95 stroker - wow that is a little over my head testing the injectors. I will try to use a infered to test exhaust readings.

 

[Patrick Feeley]

You want to use a liquid-filled gauge (0-100 psi should be fine), at the schraeder valve. If you can't find a fitting, you can remove the schraeder fitting and use a 1/8 NPT fitting. Be cautious if doing this and do not overtighten the fitting as the regulator body will crack! If you can get a long enough hose to tape the gauge to the windshield, you can look to see if the pressure is dropping under load while driving it. Cheers!