turbo944s2
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« on: October 11, 2016, 12:19:51 PM »
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I vagcomed my car today and I got a map sensor reading of 990mbar at idle. I checked the sensor, the o-ring, check for vacuum leaks, my boost gauge is reading -20 in hg. Any suggestions of what could be wrong ?
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nyet
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« Reply #1 on: October 11, 2016, 12:21:49 PM »
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I vagcomed my car today and I got a map sensor reading of 990mbar at idle. I checked the sensor, the o-ring, check for vacuum leaks, my boost gauge is reading -20 in hg. Any suggestions of what could be wrong ?
MAP is a misnomer. The stock pressure sensor location is upstream of the throttle body. Your boost gauge is likely downstream. |
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turbo944s2
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« Reply #2 on: October 11, 2016, 12:53:17 PM »
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Thanks for the response. I put a new map sensor in and it is still reading 990mbar. 990mbar is almost atmospheric pressure, so I must have a huge leak somewhere ?
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nyet
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« Reply #3 on: October 11, 2016, 12:58:48 PM »
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Thanks for the response. I put a new map sensor in and it is still reading 990mbar. 990mbar is almost atmospheric pressure, so I must have a huge leak somewhere ?
So, did you read my post explaining that your "MAP" (a MISNOMER) sensor is *upstream* of the throttle body? Any idea what that means? |
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turbo944s2
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« Reply #4 on: October 11, 2016, 01:05:20 PM »
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When you said misnomer , I thought that you meant the map sensor was broken. Up stream means it is before the throttle body. So you're saying inspect everything before the throttle body?
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nyet
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« Reply #5 on: October 11, 2016, 01:08:25 PM »
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When you said misnomer , I thought that you meant the map sensor was broken.
misnomer n 1: an incorrect or unsuitable name MAP stands for "Manifold Absolute Pressure". Is the manifold upstream or downstream of the throttle body? Up stream means it is before the throttle body. So you're saying inspect everything before the throttle body?
No. At idle, is the throttle plate closed or open? When fully open, the pressure differential between upstream and downstream of the throttle plate is near zero. When closed, what is the pressure differential? |
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« Last Edit: October 11, 2016, 01:11:41 PM by nyet »
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turbo944s2
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« Reply #6 on: October 11, 2016, 01:19:58 PM »
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The throttle plate at Idle is almost fully closed. When closed the differential pressure should be high because one side is under a vacuum and the other side is exposed to atmosphere?
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nyet
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« Reply #7 on: October 11, 2016, 01:21:26 PM »
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Almost there  |
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SB_GLI
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« Reply #8 on: October 11, 2016, 01:27:52 PM »
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What he is trying to say is that the reading is accurate. He is just trying to explain to you why it is accurate. The MAP is upstream of the throttle plate. When the plate is closed, there is no charge (or vacuum) in the charge pipes, thus the readings near atmospheric pressure.
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turbo944s2
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« Reply #9 on: October 11, 2016, 01:35:14 PM »
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Hmm is the sensor reading in absolute pressure? If it is then it's reading correctly.
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turbo944s2
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« Reply #10 on: October 11, 2016, 01:36:30 PM »
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Thanks guys. I'm getting a boost pressure deviation dtc. I'm trying to figure out why. There is a 600bar difference between the sensor and the requested. If I raise the requested up higher that should go away. I didn't want to do that blindly without some insite.
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nyet
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« Reply #11 on: October 11, 2016, 01:43:24 PM »
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Thanks guys. I'm getting a boost pressure deviation dtc. I'm trying to figure out why. There is a 600bar difference between the sensor and the requested.
Post the DTC. I doubt it is related to idle. If I raise the requested up higher that should go away. I didn't want to do that blindly without some insite.
Yes, do not raise requested higher blindly until you diagnose precisely what is going on. Post logs, preferably 3rd gear WOT. Depending on the DTC, you should not be throwing it part throttle or idle. Do not post VCDS logs. Get ME7Logger running, or take the car to a qualified mechanic. |
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SB_GLI
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« Reply #12 on: October 12, 2016, 07:15:57 AM »
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Thanks guys. I'm getting a boost pressure deviation dtc. I'm trying to figure out why. There is a 600bar difference between the sensor and the requested.
MAP reading is likely correct. You could/should verify with a manual gauge. You likely have a boost leak somewhere causing underboost. |
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turbo944s2
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« Reply #13 on: October 12, 2016, 05:40:44 PM »
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000665 - Boost Pressure Regulation
P0299 - 002 - Control Range Not Reached - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 2
Fault Frequency: 2
Reset counter: 255
Mileage: 115516 km
Time Indication: 0
Freeze Frame:
RPM: 3286 /min
Load: 21.2 %
Speed: 75.0 km/h
Temperature: 90.0°C
Temperature: 33.0°C
Absolute Pres.: 980.0 mbar
Voltage: 13.716 V
I pressurized the entire system to 20 psi last week and fixed all of the boost leaks I had. I will start working on ME7 logger asap.
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