RPMs fluctuate above 2,200

2005 FORD F-350

223,000 MILES • 6.0L • V8 • TURBO • 4WD • AUTOMATIC

05POWERSTROKEGUY

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2005 power-stroke 6.0 been head studded EGR delete sct bdx tuner and what not 223xxxmi starts great idles great runs awesome, but when get above 2,200 RPMs it'll sporadically drop and jump RPMs to what seems like shift. just curious what it could be. doesn't really affect drivability just want it to be perfect and want to fix does not have an upgraded fuel pump or lift pump.

Mar 15, 2022 at 4:00 PM

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KASEKENNY

AUTOMOTIVE REPAIR CONTRIBUTOR
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This is most likely a high-pressure fuel issue. So, we need to use a scan tool and monitor the actual vs set point fuel pressure. This will tell us what happens when the RPMs are higher and that will tell us if the fuel pressure is dropping out, which is most likely what is happening.

The fact that you do not have an upgraded lift pump or HP pump could be the issue.

I am attaching the info on an injector interrupt test. This is not the easiest test but that will also help with rough running or erratic idle issues.

However, I would pursue a fuel volume issue from the lift pump, or the high-pressure pump is not providing the proper pressure.

Images (Click to enlarge)

Mar 16, 2022 at 7:08 PM