Key on/engine off MAP readings out of whack. Should/can I recalibrate? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 02-21-2014, 12:28 AM   #1
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Default Key on/engine off MAP readings out of whack. Should/can I recalibrate?

I'm trying tune from scratch and I'm running into issues with VEAL. Could be a lot of things going on, but the first thing I want to correct is my MAP reading with key on/engine off. I noticed values in the 60's which is definitely not right. I have an MSPNP 9697 and therefore have a 4 bar sensor. I have checked for kinks and made sure TS is set to the 4 bar sensor. Still in the 60's. I also noticed that I get the same results no matter what sensor I choose (1, 2, 2.5, 3). This seems weird to me, but it may make sense to someone more knowledgeable. The car drives and idles differently as well depending on the sensor setting. It drives and idles the 2.5 bar setting (this is a base map so this could be a fluke). I dug around and saw some mention of recalibrating the sensor. Am I barking up the wrong tree and will recalibrating the sensor cause more issues if it is not the problem?
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Old 02-21-2014, 09:56 AM   #2
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Is the MS getting a signal from the MAP at all? When you drive and idle, do the map readings change?
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Old 02-21-2014, 11:12 AM   #3
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Yes. Idle reads around 40 kPa. When driving around it reads like 80's or 90's when my boost gauge is at 0 vac/boost. I've avoided boost since its a base tune. It appears to give these numbers regardless of sensor chosen.
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Old 02-22-2014, 10:00 AM   #4
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From my cursory understanding of the MAP function, it uses key on/engine off (KOEO) for baro correction. So 60 would imply you are at a rather high elevation which I don't think is even possible. However, your engine running MAP readings sound about right. I get 33 at idle and about 60 cruise hiway. WOT is always 100 since we are at sea level.

So I guess its possible for your tune to be ok if you started to tune and the KOEO reading is always the same. Having said that of course, I would want my KOEO readings to be closer to reality. Given Mannassas is 300' above sea level, you should get close to 100 KOEO reading.
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Old 02-22-2014, 12:05 PM   #5
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I know its possible to tune around an issue like this, but it makes for a lot more work and headache. VEAL tuned my light load areas into the ground when I let it run for about 15 minutes and just drove around at light load. It got to where <9% TPS was deceleration, 9% TPS was VERY slow acceleration, and >9% TPS just fell on its face. I looked and VEAL had cut all my light load cell numbers in half. I did have the cell change sensitivity turned up so that might be the entire cause, but I feel like it only amplified another problem.
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Old 02-22-2014, 12:58 PM   #6
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Quote:
Originally Posted by mx5autoxer View Post
I know its possible to tune around an issue like this, but it makes for a lot more work and headache. I did have the cell change sensitivity turned up so that might be the entire cause, but I feel like it only amplified another problem.
Diagnose the problem, do not tune around it. Post up your msq and log files too.
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Old 03-06-2014, 12:25 AM   #7
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So between the Hoth-like conditions and me having the puke-on-the-hour bug, I haven't touched or thought about the car for a week or two. Today, however, I cleared the snow off of it and drove. Engine off = 62 kPa. 10 in/Hg of vac on my boost gauge = 58 kPa. From what I read it seems like the MAP sensor is physically fixed in its calibration, so the only way to adjust it is to scale using two reference points. Does this sound correct to anyone? I'm not sure why its reading so far off in the first place, but I think I'll either call or email DIY tomorrow and see if they have any experience with this problem.
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Old 03-07-2014, 02:52 PM   #8
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Ok. I'm going to fess up to my noob stupidity in hopes of saving someone else down the road some hastle.

The problem was that I was not selecting the correct MAP sensor in both MAP setting locations. I was making changes in the Engine Constants 1 window under the Basic Settings tab, but not changing the MAP type to match in the Settings tab of the Project Properties tab.
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Old 03-07-2014, 03:14 PM   #9
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Glad to hear you got it straightened out. Props for posting the solution.

I'm installing mine this spring and it scares the hell out of me that I will do 10 little things like this and not have any clue as to fixing it.
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