limp mode? boost/sensor issue...
 

ok so aparently my o1 audi a4 1.8t is running in limp mode and is peged at 5psi of boost... i have a full borla exhaust with a cat delete pipe. ive had the exhaust on for about 5 months with no issue. i have a kn air filter and a boost gague in as well. one day i was driving and my car wouldnt get above 5psi i thought it would be a vacume leak so i checked and found nothing. then i took the negitive off the battery and reset the computer and my car was acting normal untill about 50-100 mile down the road it gos back into limp mode. if you have ne idea what i can check to figure this out or any ideas whatsoever please let me know. also if you know how to check if the maf sensor is bad with a multimeter or the o2 sensors with a multimeter could u let me know so i can check them. any suggestions will be taken to heart thanks!

It is your MAF.

Why are you so certain it's his MAF sensor? Is there a way to check if the MAF sensor is working properly without just replacing it? I've been trying to get my car out of limp mode for almost a year now.

yea if neone knows how to check the maf sensor let me know... like what ohms for what pin and what not

Unplug it.

If the car runs better w/ the MAF unplugged then thats the problem. If it still runs like shit or runs worse than before, its somethin else. Any CELs? Codes? Keep in mind that you CAN throw codes w/o a CEL

if you are going into limp mode there should be a code stored. a dying MAF would not put you into limp mode, and it sometimes doesnt store a code unless the MAF readings are way out of spec.

Sounds like a fuel trim issue that could be caused by a bad MAF, as mentioned, or it could be a leak passed the MAF that is messing things up. A leak will allow air to enter passed the MAF and the MAF readings will be low but still accurate.

I wouldnt automatically assume its the MAF. I replaced it on my old car before I found a hole in a hose. '

Do a leak test.

Mine recently started as well and my MIL light came on. I took my OBDscanner to it and i got two codes.

1 - MAF sensor output too low
2 - Boost sensor one faulty.

any idea why these two codes would pop up and make my car stumble and spit and sputter?

post the actual codes, not what your scanners definition of the codes are.

if the MAF is faulty it would cause those problems. i dont know if they meant MAP sensor instead of boost sensor...