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Discussion Starter #1
So I was driving home one day and car was running fine, all of a sudden I look over and my aeroforce and boost gauge all of a sudden isnt registering any boost its reading at -28.9, I get it home and park it and try and start it, it just sits there spinning and wont actually turn over. I wait a few hours and try and start it and it fires right up, so I go to bed. The next day I get in it and drive to work, go to a friends house after work and did some logs, logs didn't show anything weird so I go ahead and head home, on the way home it starts doing the same thing. I park in the driveway and again, car wont turn over, next morning car starts up just fine, drive to work and park and walk out about 2 hours later and it wont start. Wait till around lunch time and walk out to try again and it fires right up, then drive it home and it persists again, left it at the house and took the truck to work instead. After some suggestions I replaced the crank position sensor and that didnt help at all. I turn the accesorry mode on and the car says -28.9 on the aeroforce gauge and just sits there and tries to crank but never does. Only thing I can think of at this point is the MAP sensor, unless anyone has any other suggestions.

No engine codes or CEL had popped up during this entire ordeal. Any help is greatly appreciated.


Update: I unbolted the Supercharger lid and bolted it back down and the car fired right up, drove it up and down the street and it started having issues again, parked it and turned it off and it wont start back up again.
 

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What year is the car?
What Mods have been done?
Is it tuned? And if so have you contacted the Tuner?
 

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Discussion Starter #3
2011, already contacted the tuner and hes lost as well

mods:
NW 102 TB
2.55 upper
9.55 lower
ported heads
1 7/8 headers
alky control meth injection
ported snout
VR custom grind cam
E85
DSX aux fuel pump

and all supporting mods
 

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The barometric pressure is determined from your MAP sensor which is also used to calculate boost. Assuming your tuner did not change any baro settings. That is my first thought and a cheap/easy trial and error fix.


2011, already contacted the tuner and hes lost as well

mods:
NW 102 TB
2.55 upper
9.55 lower
ported heads
1 7/8 headers
alky control meth injection
ported snout
VR custom grind cam
E85
DSX aux fuel pump

and all supporting mods
 

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1,300 Posts
Might have your tuner look at your Startup Airflow Table and Cranking Fuel Table. Especially in the temperature range when you are getting the no start. The warmer the engine the less fuel it needs to start.
 

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Discussion Starter #6
Thanks for the help guys. My new MAP sensor comes in tonight and hopefully that will fix it. Went and fiddled with it a little last night. I unbolted the lid and left the sensor plugged in and my aeroforce read 0.0 on the boost gauge. I unplugged the sensor and it said -28.9, plugged it back in and it read 0.0. Bolted the lid back down and it still read 0.0, car fired right up, I drove it down the street and didn't have any issues, got out and gave it some more gas, as soon as I hit 10 pounds of boost it dropped back to -28.9 and started having issues again, limped it back home, turned it off and it wouldn't start. Fairly set on it being a issue with the MAP sensor.
 

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The barometric pressure is determined from your MAP sensor which is also used to calculate boost. Assuming your tuner did not change any baro settings. That is my first thought and a cheap/easy trial and error fix.
There are three MAP sensors on the V. The red label MAP is a 3 bar used for post SC pressure, one on the snout used for pre SC pressure, and a third on the front of the lid that is use as barometric (atmospheric) pressure.
 

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Discussion Starter #8
There are three MAP sensors on the V. The red label MAP is a 3 bar used for post SC pressure, one on the snout used for pre SC pressure, and a third on the front of the lid that is use as barometric (atmospheric) pressure.

hmmm was not aware of there being 3, I knew of the 2 on the lid, I'm guessing the one on the snout is the big weird box looking thing? I ordered a new 3 bar map sensor
 

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hmmm was not aware of there being 3, I knew of the 2 on the lid, I'm guessing the one on the snout is the big weird box looking thing? I ordered a new 3 bar map sensor
The box is the evap valve. The snout MAP looks just like the others and is tucked towards the driver side almost under the fuel rail. 3 bar should be the one causing issues I would think from what you've shared.
 

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Discussion Starter #10
sweet, I appreciate it, hopefully this will fix it, tired of not being able to drive it, but I really cant see what else could possibly be the issue
 

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hmmm was not aware of there being 3, I knew of the 2 on the lid, I'm guessing the one on the snout is the big weird box looking thing? I ordered a new 3 bar map sensor
The big box looking thing is the Evap purge solenoid.


In this pic number 4 is the barometric (atmospheric) and number 5 is the SC inlet.

img_20170915_183734_zpsulsy8ibq_a3fd6bdcae6f4ba9fe25e4044a24000e27c35d54.png
 
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Discussion Starter #12
for some reason, I'm not sure why, but I have never noticed the MAP sensor on the snout before... learn something new every day
 

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yes, I should have clarified. The E67 controls use three sensors technically. Form my understanding the third on the lid is used for active air/fuel adjustments and not for key-on-start adjustments. The 3 bar is the sensor used for the key-on start up adjustments.

Thank you Asteggall, looking forward to more clarity.

There are three MAP sensors on the V. The red label MAP is a 3 bar used for post SC pressure, one on the snout used for pre SC pressure, and a third on the front of the lid that is use as barometric (atmospheric) pressure.
 

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Hopefully that did it. Good Luck.
 

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Discussion Starter #16
Thanks for all the help guys, turned out to be the MAP sensor being all fucky, threw a new one in and after driving to work and doing a couple pulls it seems to be fixed, but still straying on the safe side.
 

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Good news so far. Glad it is working.

Thanks for all the help guys, turned out to be the MAP sensor being all fucky, threw a new one in and after driving to work and doing a couple pulls it seems to be fixed, but still straying on the safe side.
 

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My car did the same thing.. I was driving along on the freeway, doing up to 80 (at times) with the kiddos in the back seat. We get off the freeway, drive on the street for about 2 miles, and pull into the Mexican place for dinner (not a sound, not one issue, not one code). About an hour later, I tried to start the car and it won't turn over. I even took the blower belt off thinking that turning less components may help. Nothing.

I tried to fire her up in the morning and heard a terrible sound. I sent it to my friends shop and bingo! a piston was missing. Not scaring you, just sharing a VERY similar sounding story. However, yours has fired up since, and mine never did. But I NEVER in a million years would've known that I had lost a piston. No codes, or even loss of power. Weird.

Have a nice day.
 

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Sorry for opening up a couple year old thread. But new V owner and did some mods and having same issue. Just curious what MAP sensor? Since there are 3. Do you have the part# by chance?
 
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