Lambda Spike (WRX104X)

[PhoSho]

Howdy All,

I have gotten my car running again (04 Forester XT - EJ25 on a 104X) with a new intake manifold, injectors (1050x), rails, pump, lines, regulator, and filter. I had it idling today just trying to bleed out the cooling system. Car was idling well for a bit - no notable issues. I was out of the car and the idle dropped, motor started to struggle a bit. PCLink showed CLL Correction was adding 20% (max clamp). Nothing had changed prior to this happening; I wasn't even touching the car. My correction up to that point, with some minor initial fuel table adjustments, had the correction +/- 5% (ish). The lean spike happens right around 13:27 in the attached log. I thought I might have just run low on fuel, but my fuel pressure looks pretty stable thorough out. Eventually, it did even out. Could it have been a misfire? Motor didn't struggle as bad as I think it would have with a random multicylinder misfire.

The tune is very rough - basically just a startup/idle map, but I would like to try and figure out why this happened. Any advice would be greatly appreciated.

Google Drive - Tune and Log

[Adamw]

No I dont see anything obvious in there. But 1 thing that is a bit odd in that log is just a few seconds after that point the differential fuel pressure jumped up to 330kpa from 300, and that's when the CLL correction started going back to normal.  The fuel pump was still in low speed mode the whole time.  So possibly whatever caused that jump in fuel pressure could be affecting other things (loose battery terminal or something like that?)

You can usually roughly consider MAP x RPM as a strong relationship to airflow and injector effective PW is proportional to fuel flow, these were both stable before and after the jump in lambda and the jump in fuel pressure, so with stable air and fuel flow you should have a stable AFR (FYI, inj PW doesnt include the CLL trim), this suggests to me the change in fuel delivery is some external influence.  

 

 

[PhoSho]

Thank you Adam. I had a suspicion that it was a fuel delivery problem too - I was just hoping it would show itself in the log. I did just replace the battery with a small form version and the battery terminals are a bit small, so I will check on those. Maybe just reinstall the original battery to see if that takes care of the issue. 

 

[PhoSho]

Just an update - this same issue happened again and was consistent for several minutes. I found cylinder 2 coil plug wasn't fully clipped in and was making intermittent contact. Seated plug and all is well.