How many pres. sensors?

02greysixer

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Jun 4, 2011
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So I had my Intake Air Heater get stuck on, luckily I noticed it before things got to serious. It did however melt the map sensor, so I changed that. But something still isn't right. At idle according to my diablo I've got 2psi of boost with the key on or with the motor idling and 14.x psi of intake pressure. Is there another sensor somewhere causing me problems? I checked my dads Lbz and it had 0psi boost and 12.Xpsi of intake pressure. Anybody have any ideas?? :confused:


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02greysixer

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And forgot to add there is no actual boost pressure registering on my boost gauge. Something's got my truck playing tricks on itself :cry:


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02greysixer

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That's what I'm leaning toward, I don't have a way to check it though. My damn diablo won't read that, my dads will read his truck but his won't read mine. If that makes sense. I did unhook the baro sensors and nothing changed, maybe that indicates its bad? I wish I knew someone with efi near me! :confused:


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02greysixer

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Where's the best place to buy a baro sensor? I've tried looking but can't seem to find much info. I hope it's not a dealer only item.


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02greysixer

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So I ended up going to the dealer for the baro sensor. Oreillys wanted $430 for one :eek: dealer only wanted $100. Bought it and installed it, truck still isn't right. And the computer still thinks its got 2psi boost and 14.3 psi intake manifold pressure at idle. Wires all seem to be in good shape, no breaks or anything. So im into it with a new baro and map sensor and it's got me nowhere. I'm lost now, anyone else got any ideas?? Can this be recalibrated back to normal with efi??


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SSchmi5519

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Oct 19, 2008
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So I ended up going to the dealer for the baro sensor. Oreillys wanted $430 for one :eek: dealer only wanted $100. Bought it and installed it, truck still isn't right. And the computer still thinks its got 2psi boost and 14.3 psi intake manifold pressure at idle. Wires all seem to be in good shape, no breaks or anything. So im into it with a new baro and map sensor and it's got me nowhere. I'm lost now, anyone else got any ideas?? Can this be recalibrated back to normal with efi??


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The 14.3 means the baro is working. It is registering atmospheric psi.
 

02greysixer

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I know 14.3 is the proper reading for barometric pressure but shouldn't the intake manifold pressure be lower? At 12.3 or so? That's how my dads Lbz is


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SSchmi5519

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The computer uses the baro number to subtract from the MAP number. Thus giving you an actual manifold PSI value that is not affected by altitude.
 

02greysixer

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Just tested my map sensor by swapping it with my dads (a known good one) and it works fine in his truck. So I assume that means I have a broken wire or bad connection somewhere??


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SSchmi5519

LLY Cult Leader
Oct 19, 2008
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Just tested my map sensor by swapping it with my dads (a known good one) and it works fine in his truck. So I assume that means I have a broken wire or bad connection somewhere??


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Maybe rubbed through the wire insulation somewhere
 

02greysixer

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Well it's most likely a loose wire somewhere, I think, maybe, :confused: . I took the engine harness apart somewhat and if I pushed on it just right where everything comes together on the drivers side under the bale connectors the boost reading would drop to 0 and the manifold pressure would drop to 6.8 ( like unplugging the map sensor) I didn't see anything to obvious but hopefully I can dig further into it tomorrow, had to put it back together to drive it tonight


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JoshH

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Get an actual scan tool so you can see what the MAP and Baro sensor are reporting.
 

02greysixer

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Get an actual scan tool so you can see what the MAP and Baro sensor are reporting.

Saving my pennies right now for a V2. I don't trust the local dealership or any local shops, they'll just charge me the $85 and say everything's fine. And it really does run fine except for a very slight rough idle and slight blue/grey smoke on start up, I'd just like to know what the hell is going on. I just got done tracing the wires from baro and map to the small bale connector. No cuts or breaks in any of them. The connections inside the map plug were loose so I bent them back into shape, now it shows a constant 2psi instead of bouncing between that and 0. I tested all 3 wires for each sensor, power is a constant 5 volts to each just like they call for. Both have a solid ground with no resistance. I even traced and tested both signal wires all the way down to the ECM, both were in good shape and showed little if any resistance with the meter. I'm going to check everything once I get the V2 but I'm just at a loss right now. The computer sees and reads the map but it's like the baro is just unplugged or it doesn't even know its there. I'm hoping if I can't figure anything out there is a way to tune around this. I live in Fl so it's not like my truck has to adapt to changes in elevation, I just want to get rid of the embarrassing puff of smoke when i start it. but I would rather fix it right. Thanks to y'all that have tried to help :thumb:


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