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Proper map sensor readings
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=92011		 Page 1 of 1
Author:  mr.jerryfluffy [ Tue Jul 20, 2021 5:58 pm ]
Post subject:  Proper map sensor readings
Been chasing a p0299 for a lil bit now and it’s really starting to piss me off. Ive retraced my steps a bit and looked at the freeze frame data of the p0299 and the map reading showed 49inhg. That’s seems a bit high but The brief time I searched online I couldn’t find the right value. I never replaced my map sensor With a new one when my turbo issues started I just swapped the one that was on my blown motor… after swapping the “new” sensor on the freeze frame for the p0299 shower 48in hg. I cleaned both sensors somewhat recently and there’s nothing caked on plus car is deleted. What’s is the proper value? Thanks!!!
Author:  mr.jerryfluffy [ Tue Jul 20, 2021 6:06 pm ]
Post subject:  Re: Proper map sensor readings
Elevation for my city is about 497 feet above sea level if that makes a big difference
Author:  mrhemi [ Wed Jul 21, 2021 9:53 am ]
Post subject:  Re: Proper map sensor readings
Not knowing at what load the engine was at when you captured 49"Hg pressure makes the answer to your question difficult. Keep in mind that the reading is in absolute pressure, which includes the 29.92"Hg atmospheric pressure. So, your captured reading is only 19" of boost, which is completely plausible, but varies depending on load. I am at about the same elevation as you and both of my CRD's will see above 60" under hard acceleration. So, I do not believe your reading is "high".
Author:  WWDiesel [ Wed Jul 21, 2021 1:11 pm ]
Post subject:  Re: Proper map sensor readings
mrhemi wrote:
Not knowing at what load the engine was at when you captured 49"Hg pressure makes the answer to your question difficult. Keep in mind that the reading is in absolute pressure, which includes the 29.92"Hg atmospheric pressure. So, your captured reading is only 19" of boost, which is completely plausible, but varies depending on load. I am at about the same elevation as you and both of my CRD's will see above 60" under hard acceleration. So, I do not believe your reading is "high".

Agree, engine load factor would be most helpful.
compensating for elevation difference, 49"inhg @ his 497' elevation = 23.77psia
still a most believable and good number if taken at full load operation.
Author:  mr.jerryfluffy [ Thu Jul 22, 2021 12:06 pm ]
Post subject:  Re: Proper map sensor readings
WWDiesel wrote:
mrhemi wrote:
Not knowing at what load the engine was at when you captured 49"Hg pressure makes the answer to your question difficult. Keep in mind that the reading is in absolute pressure, which includes the 29.92"Hg atmospheric pressure. So, your captured reading is only 19" of boost, which is completely plausible, but varies depending on load. I am at about the same elevation as you and both of my CRD's will see above 60" under hard acceleration. So, I do not believe your reading is "high".

Agree, engine load factor would be most helpful.
compensating for elevation difference, 49"inhg @ his 497' elevation = 23.77psia
still a most believable and good number if taken at full load operation.


Ok I agree I looked up my air pressure to be 30, I’m also very positive that it’s at max boost because I can feel just a bit of extra lag at 50 mph. Freeze frame data showed it kicked on at 2k rpm which is consistent to the gauge at that speed. Once i floor the throttle the turbo finally gives me the extra boost I need to hit 60-80+ I’ve been reading the forums everyday and this one seemed strikingly similar to my issue: viewtopic.php?f=5&t=86734&start=40

I think I’m gonna just try retuning the car i guess fingers double crossed. Just double checking I don’t need any extra mods to run nicks stage 2 hot 811 tune? Tranny was fixed with sun coast or euro tc a long time ago.
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