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Help with dtc PO315

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Old Jul 12, 2009 | 03:53 PM
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Question Help with dtc PO315

I have my LS4 running/driving in my Fiero now and when I check for codes I am getting PO315, am I right that it is for the Crankshaft Position values not in memory?

If it is that, do you have to do a learn procedure or will it eventually "learn" and have values in its memory on its own after driving for a while?

The LS4 is out of an 06 Monte Carlo, btw, if it makes a difference.

Thanks for any help on this code.

Rick
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Old Jul 12, 2009 | 06:02 PM
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P0315 Crank Pos Sys Variation Not Learned

Have you tried to just clear the code?

Is the ECS (engine coolant sensor) working properly and no air in the system?
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Old Aug 28, 2009 | 10:40 AM
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I have no other engine codes and as far as I know the coolant temp sensor seem fine. I can drive it in a 115 weather and the temp never gets over half on the gauge. As a side note, I know the temp gauge works as it got hot from another unrelated problem, that was taken care of.

The PO315 still won't clear, in fact on the code reader, it says I have two engine codes and both say PO315?

I guess I'll just have to find a Tech II and try to clear it with that, but that will cost $$, if there was anyway to clear it without a Tech II, I'd prefer that.

Thanks for any help.
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Old Aug 28, 2009 | 10:47 AM
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You could do a crank position relearn. It will figure itself out after awhile too.
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Old Aug 28, 2009 | 10:51 AM
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How long dose a relearn usually take on its own? Days, hours, or tanks of gas? Start cycles?

Thanks
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Old Aug 28, 2009 | 11:07 AM
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40 cycles I think. I did mine with a dashhawk, and you can also in hp tuners.
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Old Aug 28, 2009 | 01:54 PM
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From when you first asked, it should of relearned the variation by now.

Your ECS must be within 3* +/-, with previous overheating it my be faulty/ inaccurate.

Your best bet is to have it checked and a relearn procedure carried out, it requires it to hit the rev limiter during the process.
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Old Aug 28, 2009 | 02:02 PM
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I was told that the other engine codes needed to be cleared first, before the relearn could happen. I knew I had a Evap system Major leak. I drove it tell I finally got around to trouble shooting it. It turned out to be a cracked purge valve hose barb. That was fixed yesterday. That one leak caused several codes. Now that it is fixed the self relearn can start. I had the car scanned and cleared then diagnosed with a Tech 2. That could not clear the P0315 because the vacuum leak caused other codes.
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Old Aug 28, 2009 | 02:09 PM
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True, I read there were no other codes. Good find hope it works out.
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Old Aug 29, 2009 | 10:09 AM
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Originally Posted by LS4 swap
I was told that the other engine codes needed to be cleared first, before the relearn could happen. I knew I had a Evap system Major leak. I drove it tell I finally got around to trouble shooting it. It turned out to be a cracked purge valve hose barb. That was fixed yesterday. That one leak caused several codes. Now that it is fixed the self relearn can start. I had the car scanned and cleared then diagnosed with a Tech 2. That could not clear the P0315 because the vacuum leak caused other codes.
Should have done the re-learn while you had the tech 2. It would have taken 5 seconds.
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Old Aug 29, 2009 | 10:58 AM
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It would not relearn then. The codes from the vacuum leak in the evap system prevented it from relearning. I did not try to find the leak til much latter.
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