Boost Measurement Variations
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Tuned
Joined: Oct 2020
Posts: 418
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From: Piedmont of N.C.
Boost Measurement Variations
I have two ways to measure boost since I have installed the EDGE CTS3. One of course, is from the OEM MAP sensor which I just replaced recently. The other method is with the EDGE EAS pressure sensor that I installed back in November of 23. To cut to the chase, the MAP sensor will always read almost double the pressure that the EAS sensor does. I actually replaced the EAS sensor after calling EDGE customer service stating what I have written here. Both sensors are brand new and still give different pressures! The measurements are taken within inches of one another. Can anyone give any insight with this discrepancy? Or should I expect this difference? Both pressures are identical to the readings I had before replacing the sensors. And by the way, the MAP sensor is Motorcraft purchased from RiffRaff.
Lead Driver
Joined: Jul 2017
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From: WV
That is odd. My boost from MAP on CTS1 will read almost directly with the mechanical gauge until reaching its 24psi limit.
There are two ways to read the MAP I think. Direct MAP reading which includes atmospheric pressure and one that corrected. What does the MAP boost read when key on engine off?
Any photos of your setup you can share?
There are two ways to read the MAP I think. Direct MAP reading which includes atmospheric pressure and one that corrected. What does the MAP boost read when key on engine off?
Any photos of your setup you can share?
Cargo Master
Joined: Apr 2022
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I would assume gauge pressure and not absolute. Or it would be a good deal more then almost double. Especially at idle/low boost.
Mountain Pass
Joined: May 2022
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Map should read near 14.7 with key on engine off.
Boost = map - baro (baro being around 14.7 or atmospheric) . So atmospheric (intake is not pressized from the turbo) would read 0 on the boost gauge.
Engine idling would read a tad lower as there is a slight vacumm. Say like 14.5.
The ford pcm will only let you read the map or boost, not both at the same time (map will start to ahow boost typically). There is another pid for boost specificly.
An aftermarket pressure sensor would see atmospheric, you would need to deduct 14.7 from the reader or better yet, subtract baro. I think you can do this if you can alter the pid equations.
Ebp sensor will always include atmosphereic values.
Atmosphereic pressure changes as you change elevation.
Boost = map - baro (baro being around 14.7 or atmospheric) . So atmospheric (intake is not pressized from the turbo) would read 0 on the boost gauge.
Engine idling would read a tad lower as there is a slight vacumm. Say like 14.5.
The ford pcm will only let you read the map or boost, not both at the same time (map will start to ahow boost typically). There is another pid for boost specificly.
An aftermarket pressure sensor would see atmospheric, you would need to deduct 14.7 from the reader or better yet, subtract baro. I think you can do this if you can alter the pid equations.
Ebp sensor will always include atmosphereic values.
Atmosphereic pressure changes as you change elevation.
Lead Driver
Joined: Oct 2005
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From: Ponca City, OK
The actual data might help get to the bottom of this. Can you load some data files or maybe just some pics or screenshots?
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Cargo Master
Joined: Apr 2022
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For info for everybody wondering on the edge if you show "boost" "ebp" or a add on edge eas sensor they all show actual gauge reading. Not absolute like some are referring to with atmospheric included.
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Thread Starter
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Tuned
Joined: Oct 2020
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From: Piedmont of N.C.
This is what I’m seeing with ignition key on engine off.
I used the RiffRaff IAH delete and get my boost here for the EAS. I might add that the other pressure sensor on my EAS setup monitors fuel pressure and it is spot on with the pressure delivered by the FASS system at +/- 65 psi.
I do have a boost fooler, but my readings are still off as they were before I added the boost fooler with the exception of the MAP sensor not displaying any more than 21 psi
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Tuned
Joined: Oct 2020
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From: Piedmont of N.C.
[QUOTE=Tpayne621;21153220]For info for everybody wondering on the edge if you show "boost" "ebp" or a add on edge eas sensor they all show actual gauge reading. Not absolute like some are referring to with atmospheric included.[/QUOTE
So, you are saying that the MAP sensor is actually reading boost on top of atmospheric pressure and the EAS sensor is displaying true boost pressure?
So, you are saying that the MAP sensor is actually reading boost on top of atmospheric pressure and the EAS sensor is displaying true boost pressure?
Thread Starter
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Tuned
Joined: Oct 2020
Posts: 418
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From: Piedmont of N.C.
Not in the vehicle right now, but it’s very close to half, with the MAP sensor being the higher of the two readings.
Cargo Master
Joined: Apr 2022
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[QUOTE=OldMechanic57;21153233]
"Boost" shows true boost. Not absolute. If any of your sensor were reading absolute they would be reading at 14.x at idle or just switched on. That's not your issue.
For info for everybody wondering on the edge if you show "boost" "ebp" or a add on edge eas sensor they all show actual gauge reading. Not absolute like some are referring to with atmospheric included.[/QUOTE
So, you are saying that the MAP sensor is actually reading boost on top of atmospheric pressure and the EAS sensor is displaying true boost pressure?
So, you are saying that the MAP sensor is actually reading boost on top of atmospheric pressure and the EAS sensor is displaying true boost pressure?