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I just want to apologize for being the new guy who shows up just to ask a dumb question, but I've searched high and low to better understand what's going on with my truck to no avail.
Basically the truck has been slow since I got it a few months back. This is my first truck, and first diesel so I just assumed an old truck would feel slow coming from a Miata set up for autocross.
About a week ago I pulled codes with a Snap On tool at our shop and got P1247, which indicated a bad MAP(At least I'd hoped), so I decided to test it by pulling the plug on the map, and I got power back! I replaced the MAP with an aftermarket brand hoping it'd fix the issue, but it persisted even after replacement. I pulled the codes after replacing it and taking it for a drive(clearing the codes prior to drive) and found a P0237 code in the system. Both indicating low boost iirc. I'm not really sure where to go at this point to resolve the issue, short of leaving the MAP unplugged permanently, so any help is appreciated!

I had heard EPB sensor/valve issues could cause similar issues to a bad MAP, so this weekend I'll be taking the sensor off to check if it's clogged. I reaaaaallly don't want it to be a bad PCM so anything I can try before replacing the PCM is a good bet

Edit: would also like to mention that I checked the connector for corrosion and replaced the hose from the MAP to the engine when doing the map
 

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NB2,

Welcome to the PSN,

With the MAP sensor unplugged the PCM defaults to a look up table that is based on other inputs. You may have a bad wire/wires. I would check each of the three wires on the MAP plug for grounding and shorting issues. You will need to pull the plug off the PCM to check the wires. Unfortunately, I don't have a wiring diagram for your year. EBV has been known to stick shut, but it really makes the truck operate like a cold dog all the time. As your power comes back with the MAP unplugged I would start with the MAP.

Cj
 

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I'm not a super duty expert, so I'm speaking in generalities here, but you've had low boost readings from two map sensors, correct?

When you unplugged the map did the truck smoke?

I would highly recommend rigging a test gauge to check your manifold pressure. Go drive it with the gauge and the scanner hooked up, compare readings. If the sensor is wrong, well then it's time to start chasing electrons. If pressure is actually low, could be an intake leak, exhaust leak, or turbo issue. Watching the EBP reading and comparing to the map reading will help in that scenario.

That's how I'd attack it.
Good luck!

Sent from my E6810 using Tapatalk
 

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With the MAP sensor unplugged the PCM defaults to a look up table that is based on other inputs. You may have a bad wire/wires. I would check each of the three wires on the MAP plug for grounding and shorting issues. You will need to pull the plug off the PCM to check the wires. Unfortunately, I don't have a wiring diagram for your year. EBV has been known to stick shut, but it really makes the truck operate like a cold dog all the time. As your power comes back with the MAP unplugged I would start with the MAP.

Cj
Should be the same L99 - 2003. What circuit do you desire? Jax
 

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P1247 - Turbo Boost Pressure Low

P0237 - Turbo Boost Sensor A Circuit Low Input - MIL Lit
 

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MAP should be Connector 176, Wire Assy 12A581 -- no page indicated. Anyone want to give a stab at the circuit?
 

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On a 97 the sensor is hooked up with Brn/Wht being Vref (5 volts I think), Gry/Red is Sig Rtn (ground), and Lt Grn/Blk MAP (the sensor signal itself). I would hazard that there may be an open circuit on one of the wires. Somewhere around here someone has posted the PCM pinouts for the later 7.3 engines.
 
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I will add that you should try a Motorcraft part. The last time I ever bought after market parts for a Ford was a MAP sensor from AutoZone and it ended up costing me 2 hours of troubleshooting before I figured out the part was no good.
 
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