2017 Subaru WRX 2.0 Turbo Cam Crank Correlation

Kurt Diagnostician Saskatchewan Posted   Latest   Edited  
Unsolved
Driveability
2017 Subaru WRX 2.0L (FA20F) 6-spd (TY751)
P0018 — Crankshaft Position - Camshaft Position Correlation Bank 2 Sensor A

I've got this vehicle with a P0018 Crank cam correlation bank 2 sensor A. Scoped cam and crank waveforms on both sides and compared it to a known good. The timing appears to be in time. The vvt learn values for the exhaust cam are 110 degrees and 111 degrees and fluctuate 0.1 degrees with the engine running. The intake cam learned values are 95.7 degrees bank 2(problem side) and 81.3 on bank 1 with no fluctuations. So the questions I have are how are these values obtain/learned by the ECM? Why/how can they be reset? 14 degrees difference is a lot and should have shown up on the scope patterns. Anyone have more experience with this Subaru system?

No drivability, starts and runs fine. 

Thanks in advance

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Shane Technician
Massachusetts
Shane
 

What I've been told on these systems is that the ecm will learn these values at random times and there is no function to clear or relearn them. They are stored in the eeprom in the pcm. The only options are to drive it until they relearn again( who knows how long that will take) or replace the pcm. If someone has takin the time to figure out where in the eeprom this data is stored and share that…

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Kurt Diagnostician
Saskatchewan
Kurt
 

Thanks Shane, that was a good listen

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Thanks
Shane Technician
Massachusetts
Shane
 

All the podcasts are worth listening to however this is the subaru one. autodiagpodcast​.​com…

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Michael Mobile Technician
Utah
Michael
   

Kurt, The OFFICIAL solution is to replace PCM. Other solutions are being developed.

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Eric Owner/Technician
Wisconsin
Eric
 

Please keep us informed about this. Thanks. My email is: e…@gmail dot com

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Geoff Diagnostician
Hawaii
Geoff
 

I liked in the Subaru VVT class (online recently) when the OE Subaru instructor said "we used to have a reset in the SSM (scan tool) for learned VVT offset, but THEY took it away from us....so now you do a chain job and find out you need an ECM too"

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Eric Owner/Technician
Wisconsin
Eric
 

So, that means it was possible to reset the learned timing offset with a scan tool. Maybe an enterprising aftermarket company will step up and add it to their scan tool.

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Geoff Diagnostician
Hawaii
Geoff
 

or a good coder could hack the Re-Flash software to accept the "same" software to be re-installed. (?)

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Leo Technician
New York
Leo
 

Hi Kurt- before replacing the ECM, it is crucial to confirm that the issue that caused the learning values to push out of margins in the first place is no longer present. If base correlation is good (which you seem to have verified, and 99% of the time actual correlation is not the cause of these codes anyway) then the health of the system can be (and should be) verified with Mode 6 data. TSB…

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Kurt Diagnostician
Saskatchewan
Kurt
 

Yes and this is my exact hang up on not replacing the ECM at this point. The oil was dark, over full and 6000 km overdue. Other than that there is nothing Ponting me in any other direction of a system fault. Thought if I could clear the learned values easy enough that I could see how they react, but as I suspected that is not really an option. I'll get mode 6 data collected. Thank you everyone…

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Chris Owner/Technician
California
Chris
 

Hey kurt i thought the limit was 9 deg. Variation if u can watch all cams on start up is where I have seen it go beyond that and set correlation codes for 1 bank or the other.

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Kurt Diagnostician
Saskatchewan
Kurt
 

What is it at start up that would cause it to go out but while running it seems to be okay. I'll have a look at start up information and see what's happening.

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Chris Owner/Technician
California
Chris
 

I have had a couple cases where a cams sprocket lock position failure cause timing to vary by over the 9 deg. On initial start up and code,but run all day without symptoms.

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