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odd fuel trims crop up on high mileage.

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vagike

Newbie
Location
Edmonton
so i have been throwing parts at my car for a few weeks now trying to correct my fuel trims.
my idle trim is between -1.5 & -2.1
my partial trim is between +16 & +21, which is forcing the ecu to cut boost back.
i have been on APR's stage 2+ for over 110000kms.
vehicle mileage is almost 185000kms.
i've replaced pcv, maf, valve cover, and O2.
i've even bypassed the pcv from the intake manifold, to rule a heavy leak into the crankcase.
i've ran the car with the maf disconnect to rule out the aftermarket intake.
looking for more ideas to diagnose this issue.
 
V

vagike

Newbie
Location
Edmonton
Thanks for your input.

Looks like I probably burnt out the top piston ring on all the cylinders.
140 psi dry test, 180 wet test when doing a compression test.
She isn't blowing any blue smoke, yet, but I've got a sh*t ton of blow-by.
 
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vagike

Newbie
Location
Edmonton
Revisiting the post, cause I still have issues

I've re-ringed the engine, rock-solid compression on dry test now.

In the process of diagnosing this issue further, I did find that my in-tank pump was dying (90% duty at 3000rpm), but had replaced the fuel filter to too long ago.
Then found my N75 was dying too; replaced that.
Replace my camfollower, just because it had ~110000KMS; wear was uniform, still showed signs that it was rotating properly.
Check resistance on HPFP driver (n276); 2.1 ohms, 'spec' is within 5 ohms.
Logged the rail pressure, and requested vs actual was within +/-5bar difference all the way to redline.
Even swapped to my old stock HPFP, and flashed down to stock.

Recently,
When the weather was around ~25C or warm, the Partial trims still stayed ~18%.
Just got hit with some temps below 10C, and the Partial trims are maxed at 25%.

But still doesn't post a CEL.

Thoughts?
 
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