APR K04, terrible mileage and intermittent underboosting - HELP!! (Logs included)

[B8Buckeye]

i have been working with Shawn down at 1552 and directly with APR to figure out what is up with my car. we have replaced a lot of parts and not gotten any closer to a fix. all the mods are listed in my sig. here is what i have been dealing with. i am open to ideas!

this all started because i was getting terrible gas mileage - about 13 city and 19 highway - and i was having an intermittent boost problem. around town i boost fine - spike around 19-20 and hold at 16-17. once i get out on the highway and cruise for about 10 minutes, my boost drops by a full 10 psi. it will peak around 9 and hold at 7. i was not getting any CELs and I didn't have a VAG cable, so i don't know if there were any other codes.

i did a few things to try to fix the problem, including getting a VAG cable to help with the diagnosis. i did a triple sea-foam treatment, changed the oil, put in NGK BKR7E spark plugs gapped at .28 and replaced the DV - no improvement. i also did a pressure test on the system & found no vac or boost leaks. i checked the codes and got a P0171 - system too lean.

next, i replaced the MAF - no change. replaced the primary O2 sensor - no change. pulled a P0141 code (once, but never again) and then started pulling P1128 - system too lean. i get the P1128 code over & over now, and sometimes it throws a CEL. i also replaced my coolant flange and engine coolant temperature sensor and N75 valve. nothing has made any improvement. my mileage still sucks and i can't boost over 7psi once i drive on the highway for more than 10 minutes.

here are a few logs i ran today - all of these are 3rd gear pulls from 2k to 6500 rpm.

the first 2 were this afternoon when the car was boosting fine:





these next 2 are the same channels but from the evening when the car was not boosting well. i had a CEL on at the time.





channel 115 in the evening run tells the boost story. the car is requesting the right amount of boost, but it isn't making it. once i clear the codes, i'm back to full boost. WTF?!?!? i think that is about the entire story. can anyone help?! all i want is 18-19psi boost and 28mpg highway with no lean codes or CELs. any thoughts from anyone?! thanks!!

btw, here is a picture of the car...

[actlsub9]

Log block 003 next time it happens to see your throttle % while at WOT.

[Groove1797]

Welcome to my world! If you have not noticed, your maf readings are low too. My logs are basically identical.

[B8Buckeye]

Log block 003 next time it happens to see your throttle % while at WOT.

the 1st and 3rd logs capture block 003...

[B8Buckeye]

Welcome to my world! If you have not noticed, your maf readings are low too. My logs are basically identical.

from my run this afternoon my MAF reading was about 180 at 5900 rpm - that is acceptable isn't it? i know when i was having the boost problem tonight, the MAF reading was closer to 150 at 5900 rpm...

[actlsub9]

the 1st and 3rd logs capture block 003...

Yea sorry I meant a different block, something with throttle valve angle. Maybe 060? I can't remember.

[Groove1797]

On the first logs you should still have a few more grams. Do you get the "lower boost limit exceeded" CEL? My is basically permanent.

[B8Buckeye]

On the first logs you should still have a few more grams. Do you get the "lower boost limit exceeded" CEL? My is basically permanent.

i have never gotten that CEL. do you know what # it is?

[Groove1797]

P0229-002.. I think

[B8Buckeye]

^^ i've never gotten that code...

anyone see anything in these logs that they have any advice on given the repairs i've already made??