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Old 07-09-2012, 04:43 PM   #1
jhornik
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Default 37.01 PSI...is this possible?

Hey all, here is a datalog I just took on my 2011 WRX Cobb Stg 1 93 oct w/AEM intake. Line 26 showing 37.01 PSI can this be correct or am I reading it wrong, and does everything else look okay? As far as I can tell everything else looks good but I'm no Pro. Thx

https://docs.google.com/spreadsheet/...0TkQzZ1E#gid=0
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Old 07-09-2012, 05:00 PM   #2
Cobb Tuning
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Originally Posted by jhornik View Post
Hey all, here is a datalog I just took on my 2011 WRX Cobb Stg 1 93 oct w/AEM intake. Line 26 showing 37.01 PSI can this be correct or am I reading it wrong, and does everything else look okay? As far as I can tell everything else looks good but I'm no Pro. Thx

https://docs.google.com/spreadsheet/...0TkQzZ1E#gid=0
You'll need to change the permissions to public in order for anyone to view it.

Bill
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Old 07-09-2012, 05:12 PM   #3
jhornik
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Old 07-09-2012, 08:07 PM   #4
Black94Snake
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is it repeatable? Do you have a boost gauge? I would lean towards possibly having a bad MAP sensor
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Old 07-10-2012, 12:09 AM   #5
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Could be one of two things - the ECU sending bad data to logger (happens occasionally, but should be rare) or an issue with the MAP sensor. Hard to tell one or the other as it occurred in the middle of a shift (so we can't see if the ECU reacted to it or not). It is also possible not to hit the boost limit fuel cut if this inaccurate spike (say if from MAP sensor) is very brief (boost has to exceed the current boost limit for a short period of time for it be activated).

I would keep logging and see if it happens again. If it does, then likely there's some issue with the MAP sensor. Has the sensor been touched (due to repair or otherwise) on this car or anything in the vicinity?

Bill
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Old 07-10-2012, 10:06 AM   #6
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I'm thinking it had to be an error, I've done several more runs and have not been able to reproduce it. Thx
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Old 07-10-2012, 03:10 PM   #7
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Well maybe I thought too soon. Got another reading today of 38.07. In regards to the MAF sensor, if that is the problem, what should I do to correct it? Should I just make sure it's on tight or clean it or what? I did just recently install the AEM CAI so that could be it. I'm not getting any CEL's or anything though for over boost.
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Old 07-10-2012, 03:46 PM   #8
Black94Snake
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MAP SENSOR


not MAF.
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Old 07-10-2012, 03:57 PM   #9
jhornik
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MAP SENSOR


not MAF.
thanks for the correction but doesn't help me much.....that being said any further action I should take?
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Old 07-10-2012, 04:09 PM   #10
Black94Snake
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Quote:
Originally Posted by jhornik

thanks for the correction but doesn't help me much.....that being said any further action I should take?
Maybe you should re-read your own thread and address the questions which have been posed.

Quote:
Originally Posted by Black94Snake
is it repeatable? Do you have a boost gauge? I would lean towards possibly having a bad MAP sensor
I asked for a reason. Do you SEE a spike?

Quote:
Originally Posted by Cobb Tuning
Could be one of two things - the ECU sending bad data to logger (happens occasionally, but should be rare) or an issue with the MAP sensor.
Quote:
Originally Posted by Cobb Tuning
I would keep logging and see if it happens again. If it does, then likely there's some issue with the MAP sensor. Has the sensor been touched (due to repair or otherwise) on this car or anything in the vicinity?

Bill
if you keep seeing the bad data, but don't see it reflected on a gauge, maybe you should remove your hat rack from your fart box and replace your MAP sensor.
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Old 07-10-2012, 04:12 PM   #11
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37 PSI is only possible on EVO's =)
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Old 07-10-2012, 04:15 PM   #12
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It is repeatable per the data log but I do not have a boost gauge.....and I'll make sure to remove that hat rack. Anyway what are the consequences if I do not replace the MAP?
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Old 07-10-2012, 04:24 PM   #13
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fyi, the stock map sensor isn't capable of reading boost this high. so my guess would be an error in the data. highest reading the stock map sensor can output is about 25psi.
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Old 07-10-2012, 04:28 PM   #14
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are you sure you were logging manifold relative pressure not manifold absolute pressure
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Old 07-10-2012, 04:50 PM   #15
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are you sure you were logging manifold relative pressure not manifold absolute pressure
It's PSI I'm reading on the data log
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Old 07-10-2012, 05:00 PM   #16
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We are certainly not dealing with an actual boost spike here - no way you are going see boost that high on the stock turbo regardless let alone a 20+ psi spike in half a second.

amalgrover has a good point - even if the sensor was defective and pegged at 5 volts, the most you would see with this car and the stock MAP sensor/calibration would be about 27 psig at sea level. Bad logging data makes the most sense here. But, I would add barometric pressure and manifold absolute pressure to your logs. "Boost" monitor in the logs is in relative pressure, but it is calculated by ECU as (manifold abs. pressure - baro. pressure). So, if there was an issue with the baro. pressure reading, it would impact the boost monitor. But, the numbers don't really jive with 37 psig (even if baro pressure was reading at 0 psi, you would have to hit 22 psig, which doesn't make sense in your first log). The calculated load monitor also shows a value over 7.5 g/rev in that line, but this is not reflected in the airflow value. That makes me think these two monitors (boost and calculated load) had bad data in the ECU's response. Can you post the log with the second example of the issue?

Bill
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Old 07-10-2012, 05:41 PM   #17
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Here is the link with the new log.

https://docs.google.com/spreadsheet/...Ud4SmtEWmoyN0E

Also, should I be concerned with the knock that is high and it's while it's under load? I've read where the flat foot shift can throw that off sometime but not sure that's the problem here.

Thx
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Old 07-11-2012, 10:49 AM   #18
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Here is the link with the new log.

https://docs.google.com/spreadsheet/...Ud4SmtEWmoyN0E

Also, should I be concerned with the knock that is high and it's while it's under load? I've read where the flat foot shift can throw that off sometime but not sure that's the problem here.

Thx
Definitely the logging data getting corrupted somewhere along the line. Has this car had any repairs at all? Been in an accident? I was thinking maybe you had a loose ground since it happens in-between shifts.

What you are seeing as far as the feedback knock correction is known as throttle mash/shift knock as is generally noise. Keep in mind the ECU holds the correction and "slowly" ramps it back to zero, so the only perceived event(s) is when feedback correction drops as compared to the previous line. This kind of false knock can occur even when not using flat-foot shift.

Bill
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Old 07-11-2012, 11:05 AM   #19
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Thanks Bill. As far as accidents or repairs go, no nothing has been done. I am the only owner of the vehicle and it has never been in an accident or needed any major repair. Really the only work that has been done on the car is general maint such as oil changes. I also installed the AEM CAI as mentioned but that's it. You think I should reset the ECU and see if I continue getting the same results?
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Old 07-11-2012, 11:14 AM   #20
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Thanks Bill. As far as accidents or repairs go, no nothing has been done. I am the only owner of the vehicle and it has never been in an accident or needed any major repair. Really the only work that has been done on the car is general maint such as oil changes. I also installed the AEM CAI as mentioned but that's it. You think I should reset the ECU and see if I continue getting the same results?
I don't think resetting the ECU will matter, but it woudn't hurt. Do more data logging and if it happens fairly frequently, then I would give our tech support people a call: 866-922-3059. They may have additional troubleshooting steps to work through.

Bill
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Old 07-11-2012, 11:21 AM   #21
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Great, will do Bill....thanks again.
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Old 07-11-2012, 11:33 AM   #22
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This same thing happened to me. Resetting the ECU didn't fix anything. I reflashed the map (which also resets the ECU) and it did it again. Reflashed for a second time and everything went back to normal and I haven't seen this happen in 2-3 months.

I think it's just a weird fluke. Could've been a bad/semi-corrupt flash image, who knows.
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Old 07-11-2012, 05:07 PM   #23
fastblueufo
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Quote:
Originally Posted by jhornik View Post
Hey all, here is a datalog I just took on my 2011 WRX Cobb Stg 1 93 oct w/AEM intake. Line 26 showing 37.01 PSI can this be correct or am I reading it wrong, and does everything else look okay? As far as I can tell everything else looks good but I'm no Pro. Thx

https://docs.google.com/spreadsheet/...0TkQzZ1E#gid=0
I've seen this issue on mostly 08 and newer cars. It also will do it on the romraider logger so I'm sure its a sensor issue or ecu issue. Its never more than one line of data. Happens when logging a wideband sensor t times also.
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