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MAP sensor- reading vacuum?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=80926		 Page 1 of 1
Author:  flash7210 [ Mon Dec 22, 2014 9:01 pm ]
Post subject:  MAP sensor- reading vacuum?
Normally, when I view my sensors through torquePro, my MAP sensor shows 0.0 to 0.3 psi BOOST at idle. Today I noticed that it showed 3.5 mm/Hg VACUUM at idle.
Even showed the exact same reading with key-on, engine-off.

No drivability problems, no CEL code indicating a bad MAP.

So, whats going on here? Bad MAP sensor?
Or is it my current altitude?
I'm not in FL today at 50 ft above sea level.
I'm in the CA high desert at almost 4000 ft.
Author:  gmctd [ Mon Dec 22, 2014 10:33 pm ]
Post subject:  Re: MAP sensor- reading vacuum?
:BINGO: You guessed it - at one time production vehicles intended for altitude service required recalibration of the carbureted systems - cars bought down lo and driven hi, or cars bought hi and driven down lo were at times untractable without recalibration - flatlanders driving thru hi mountain passes often noted less than spectacular engine operation - EFI has solved that problem, at the very least

Pay attention to that reading and you can quickly spot a dirty air filter
Author:  mass-hole [ Tue Dec 23, 2014 10:17 am ]
Post subject:  Re: MAP sensor- reading vacuum?
Mine reads like 2 psi at idle on Torque but I always just thought the turbo was spinning at idle. I guess i need to offset it.
Author:  gmctd [ Tue Dec 23, 2014 11:48 am ]
Post subject:  Re: MAP sensor- reading vacuum?
Considerinig that GDE modified BOSCH ECM programming to meet EPA specifications, and they recently stated that EGR is used for ~1min after startup, look at the values during startup and idle - should indicate if any offset is required - might be a good idea to post the numerical values for posteriority...............
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