MAP - sensor reading drop out on high boost.
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Cross-Country
Joined: Aug 2007
Posts: 72
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From: Arendal, Norway
MAP - sensor reading drop out on high boost.
Hi y'all,
2000 7.3 Auto running 238/80's with a Hydra and supporting tunes.
MAP reading/reaching max 24 psi @ WOT - the pressure reading drops back to 2-4psi and stay like this for the rest of the run until next gear change. Then it happens all over again.
I would suspect this to happened with a OEM engine with no boost fooler attached, due to the de-fueling in the map.
This should be a 40psi set up with fuel, injectors, turbo, intake, exhaust etc. and I did see 52 psi EBP at the highest.
This engine hasn't any manuel boost gauge attached - readings are MAP and Intake Air Pressure readings only - trough the OBDII port.
He's running an aftermarket boost fooler - set to some 24 psi max bleed off pressure from factory.
Is the bosst fooler not working correctly, not bleeding off as it should - causing the MAP sensor to overload and drop to nearly zero reading?
There is no de-fueling present and I think this is caused by the tune deleting this factory setting.
Engine runs good and pull very strong. The owner did not noticed any problem related to this att all. It was just me doing regular maintainance
going trough sensors whilst performing WOT runs - when the drop in MAP readings caught my eye.
What are your experience with boost foolers and how they are suppost to work towards what actually happends when in use?
Do we need to replace the boost fooler and start monitoring its performance again?
The MAP sensor checked out fine when tested - same with EBP sensor.
Thank you for helping me out,
Helge ( Norwegian PSD addict)
2000 7.3 Auto running 238/80's with a Hydra and supporting tunes.
MAP reading/reaching max 24 psi @ WOT - the pressure reading drops back to 2-4psi and stay like this for the rest of the run until next gear change. Then it happens all over again.
I would suspect this to happened with a OEM engine with no boost fooler attached, due to the de-fueling in the map.
This should be a 40psi set up with fuel, injectors, turbo, intake, exhaust etc. and I did see 52 psi EBP at the highest.
This engine hasn't any manuel boost gauge attached - readings are MAP and Intake Air Pressure readings only - trough the OBDII port.
He's running an aftermarket boost fooler - set to some 24 psi max bleed off pressure from factory.
Is the bosst fooler not working correctly, not bleeding off as it should - causing the MAP sensor to overload and drop to nearly zero reading?
There is no de-fueling present and I think this is caused by the tune deleting this factory setting.
Engine runs good and pull very strong. The owner did not noticed any problem related to this att all. It was just me doing regular maintainance
going trough sensors whilst performing WOT runs - when the drop in MAP readings caught my eye.
What are your experience with boost foolers and how they are suppost to work towards what actually happends when in use?
Do we need to replace the boost fooler and start monitoring its performance again?
The MAP sensor checked out fine when tested - same with EBP sensor.
Thank you for helping me out,
Helge ( Norwegian PSD addict)
Lead Driver
Joined: Jul 2017
Posts: 6,854
Likes: 2,331
From: WV
The MAP can only read up to 24 or 25 psi, it will never show more.
I expect maybe the overboost control regulator is allowing it to get just slightly over max for the MAP and causing the funny readings.
Try adjusting the OCR down just a bit.
Of course you will have to add a manual boost gauge if you want to read actual boost under these conditions.
Typically tunes will write out de-fueling like you said.
I think the EBP sensor will only read to 52psi, so he is probably at the limit of that sensor as well. Might want to keep an eye on if it flattens out at 52 and for how long. This may give you a guess as to how much he might be overshooting the sensor limit.
I expect maybe the overboost control regulator is allowing it to get just slightly over max for the MAP and causing the funny readings.
Try adjusting the OCR down just a bit.
Of course you will have to add a manual boost gauge if you want to read actual boost under these conditions.
Typically tunes will write out de-fueling like you said.
I think the EBP sensor will only read to 52psi, so he is probably at the limit of that sensor as well. Might want to keep an eye on if it flattens out at 52 and for how long. This may give you a guess as to how much he might be overshooting the sensor limit.
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