05 BEW TDI Stg1 Tuned limp mode, random loss of power

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04_sti

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For the past month or so, the DD has been undergoing random losses of power. After searching the interwebs, most seem to call this limp mode, even though no codes are thrown nor is it a consistent thing. Ive had the power loss after a few minutes of driving while the car is warming up, it happens when the car is fully warm. Ive had the power come back after idling for a minute and ive had it come back while under full throttle or full boost.

I hooked up the vagcom and did a measuring block track of the boost specified and actual and both were right on target while under full throttle. The maf hits over 1k g/min under full throttle. Today i tested the n75 valve at idle from the output tests and i could see the lamda %, boost specified and charge duty cycle all fluctuate as it should. Im kind of stumped at this point. Can anyone recommend anything further from here?

A side note, my idle fuel deviation % is a bit high on cylinder 2/4. Its around +.75/-.80 fluctuating to 1.0/-1.1 after idling for several minutes. I have diesel purge on order and hope to correct that by flushing the injectors next weekend.

EDIT: Air filter is clean, fuel filter is 10k old
 
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04_sti

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Bump

Problem went away immediately after plugging in and logging. Very weird. Didnt make any changes and no problems since. Ill keep this thread updated if anything changes.
 
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04_sti

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A year and a half later, no problems since. However i think the original problem was from the turbo VVT not working properly. Ive read that they can become rusted and not function properly. The car now has 235k and no problems since. OEM cam as well.
 
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