WTF?! 6.0 F550 14psi of boost KOEO

BlackSkyRacing

BlackSkyRacing

Living Under a Rock
Joined
Mar 22, 2007
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1,394
So, I've got an F550 sitting in front of me with an overboost problem. It didn't throw a code for overboost, but based on the customer description of a surge on hills with a noise that sounded like "wooshing air" I kinda figured that's what it was... Went out and hooked the scanner up and according to that the PCM is seeing 14psi of boost KOEO and at KOER (@ idle) as well as 14psi of EBP KOEO and 17psi EBP KOER (@ idle). Replaced both EBP and MAP sensors and I'm still getting the same readings :bang

VREF is 4.98 and 4.99 The MAP sensor shows 1.28v (backprobed) KOEO and the EBP shows .87v (backprobed) KOEO. I'm not a Ford guy and Mitchel is completely useless at showing me minimum voltage or voltage range for either sensor.

I usually work on tractors, so I'll admit I'm an idiot with anything electronic beyond what I've already done. So any help would be great :bow:

Oh yeah, and the EBP was completely pluged as well as the tube, so I cleaned out the tube when I replaced the sensor.
 
Must be thinking the PSIG is his boost pressure :doh:
 
LReiff said:
Atmospheric pressure, most ecms show 14-14.5 in KOEO.
Click to expand...

Mo Smoke said:
Must be thinking the PSIG is his boost pressure :doh:
Click to expand...

:bang:bang:bang yep...Forgot that Manifold Absolute Pressure truly means ABSOLUTE pressure :doh: The worst part is I chased my tail on that for way too long before I remebered my high school physics, and I start college this fall to be a science teacher LOL

Turned out that the EGR valve was just NASTY, cleaned it out and it helped, but it still surged if you were really on it. So I replaced it and it was fine. I would have cleaned out the cooler too, but the guy was in the middle of a delivery route when it started acting up and just wanted to finish his day out.
 
don't feel bad, the simple stuff is easy to overlook when you've been working on stuff for a while... glad you got it figured out :D
 
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